OData Version 4.0 Part 2: URL Conventions
Committee Specification Draft 02 /
Public Review Draft 02
24 June 2013
Specification URIs
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Technical Committee:
OASIS Open Data Protocol (OData) TC
Chairs:
Barbara Hartel (barbara.hartel@sap.com), SAP AG
Ram Jeyaraman (Ram.Jeyaraman@microsoft.com), Microsoft
Editors:
Michael Pizzo (mikep@microsoft.com), Microsoft
Ralf Handl (ralf.handl@sap.com), SAP AG
Martin Zurmuehl (martin.zurmuehl@sap.com), SAP AG
Additional artifacts:
Related work:
This specification is related to:
Declared XML namespaces:
Abstract:
The Open Data Protocol (OData) enables the creation of REST-based data services, which allow resources, identified using Uniform Resource Identifiers (URIs) and defined in an Entity Data Model (EDM), to be published and edited by Web clients using simple HTTP messages. OData version 4.0 defines the core semantics and facilities of the protocol, a set of recommended (but not required) rules for constructing URLs to identify the data and metadata exposed by an OData service as well as a set of reserved URL query string operators, an Entity Data Model (EDM), and an XML representation of the entity data model exposed by an OData service. OData Atom Format version 4.0 extends the former by defining representations for OData requests and responses using an Atom format.
Status:
This document was last revised or approved by the OASIS Open Data Protocol (OData) TC on the above date. The level of approval is also listed above. Check the “Latest version” location noted above for possible later revisions of this document.
Technical Committee members should send comments on this specification to the Technical Committee’s email list. Others should send comments to the Technical Committee by using the “Send A Comment” button on the Technical Committee’s web page at http://www.oasis-open.org/committees/odata/.
For information on whether any patents have been disclosed that may be essential to implementing this specification, and any offers of patent licensing terms, please refer to the Intellectual Property Rights section of the Technical Committee web page (http://www.oasis-open.org/committees/odata/ipr.php).
Citation format:
When referencing this specification the following citation format should be used:
[OData-Part2]
OData Version 4.0 Part 2: URL Conventions. 24 June 2013. OASIS Committee Specification Draft 02 / Public Review Draft 02. http://docs.oasis-open.org/odata/odata/v4.0/csprd02/part2-url-conventions/odata-v4.0-csprd02-part2-url-conventions.html.
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Table of Contents
4.1 Addressing the Model for a Service
4.2 Addressing the Batch Endpoint for a Service
4.3.2 Canonical URL for Contained Entities
4.3.3 URLs for Related Entities with Referential Constraints
4.4 Addressing References between Entities.
4.7 Addressing a Property Value
4.8 Addressing the Count of a Collection
4.10 Addressing the Media Stream of a Media Entity
4.11 Addressing the Cross Join of Entity Sets
4.12 Addressing All Entities in a Service
5.1.1 System Query Option $filter
5.1.1.1.4 Greater Than or Equal
5.1.1.1.11 Logical Operator Examples
5.1.1.2.7 Arithmetic Operator Examples
5.1.1.6.2 Complex and Collection Literals
5.1.2 System Query Option $expand
5.1.3 System Query Option $select
5.1.4 System Query Option $orderby
5.1.5 System Query Options $top and $skip
5.1.6 System Query Option $count
5.1.7 System Query Option $search
5.1.8 System Query Option $format
The Open Data Protocol (OData) enables the creation of REST-based data services, which allow resources, identified using Uniform Resource Locators (URLs) and defined in a data model, to be published and edited by Web clients using simple HTTP messages. This specification defines a set of recommended (but not required) rules for constructing URLs to identify the data and metadata exposed by an OData service as well as a set of reserved URL query string operators, which if accepted by an OData service, MUST be implemented as required by this document.
The [OData-Atom] and [OData-JSON] documents specify the format of the resource representations that are exchanged using OData and the [OData-Protocol] document describes the actions that can be performed on the URLs (optionally constructed following the conventions defined in this document) embedded in those representations.
Services are encouraged to follow the URL construction conventions defined in this specification when possible as consistency promotes an ecosystem of reusable client components and libraries.
The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in this document are to be interpreted as described in [RFC2119].
[OData-ABNF] OData ABNF
Construction Rules Version 4.0.
See the link in "Additional artifacts" section on cover page.
[OData-Atom] OData ATOM Format
Version 4.0.
See link in "Related work" section on cover page.
[OData-CSDL] OData Version
4.0 Part 3: Common Schema Definition Language (CSDL).
See link in "Additional artifacts" section on cover page.
[OData-JSON] OData JSON Format Version
4.0.
See link in "Related work" section on cover page.
[OData-Protocol] OData
Version 4.0 Part 1: Protocol.
See link in "Additional artifacts" section on cover page.
[OData-VocCore] OData Core Vocabulary.
See link in "Additional artifacts" section on cover page.
[RFC2119] Bradner, S., “Key words for use in RFCs to Indicate Requirement Levels”, BCP 14, RFC 2119, March 1997. http://www.ietf.org/rfc/rfc2119.txt.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, “Uniform Resource Identifier (URI): Generic Syntax”, STD 66, RFC 3986, January 2005. http://www.ietf.org/rfc/rfc3986.txt.
[RFC5023] Gregorio, J., Ed., and B. de hOra, Ed., “The Atom Publishing Protocol.”, RFC 5023, October 2007. http://tools.ietf.org/html/rfc5023.
Keywords defined by this specification use this monospaced font.
Normative source code uses this paragraph style.
Some sections of this specification are illustrated with non-normative examples.
Example 1: text describing an example uses this paragraph style
Non-normative examples use this paragraph style.
All examples in this document are non-normative and informative only.
All other text is normative unless otherwise labeled.
A URL used by an OData service has at most three significant parts: the service root URL, resource path and query options. Additional URL constructs (such as a fragment) can be present in a URL used by an OData service; however, this specification applies no further meaning to such additional constructs.
Example 2: OData URL broken down into its component parts:
http://host:port/path/SampleService.svc/Categories(1)/Products?$top=2&$orderby=Name
\______________________________________/\____________________/
\__________________/
|
| |
service
root URL resource path query options
Mandated and suggested content of these three significant URL components used by an OData service are covered in sequence in the three following chapters.
OData follows the URI syntax rules defined in [RFC3986] and in addition assigns special meaning to several of the sub-delimiters defined by [RFC3986], so special care has to be taken regarding parsing and percent-decoding.
[RFC3986] defines three steps for URL processing that MUST be performed before percent-decoding:
· Split undecoded URL into components scheme, hier-part, query, and fragment at first ":", then first "?", and then first "#"
· Split undecoded hier-part into authority and path
· Split undecoded path into path segments at "/"
After applying these steps defined by RFC3986 the following steps MUST be performed:
· Split undecoded query at "&" into query options, and each query option at the first "=" into query option name and query option value
· Percent-decode path segments, query option names, and query option values
· Interpret path segments, query option names, and query option values according to OData rules
One of these rules is that single quotes within string literals are represented as two consecutive single quotes.
Example 3: valid OData URLs:
http://host/service/People('O''Neil')
http://host/service/People(%27O%27%27Neil%27)
http://host/service/People%28%27O%27%27Neil%27%29
http://host/service/Categories('Smartphone%2FTablet')
Example 4: invalid OData URLs:
http://host/service/People('O'Neil')
http://host/service/People('O%27Neil')
http://host/service/Categories('Smartphone/Tablet')
The first and second examples are invalid because a single quote in a string literal must be represented as two consecutive single quotes. The third example is invalid because forward slashes are interpreted as path segment separators and Categories('Smartphone is not a valid OData path segment, nor is Tablet').
The service root URL identifies the root of an OData service. A GET request to this URL returns the format-specific service document, see [OData-JSON] and [OData-Atom].
The service document enables simple hypermedia-driven clients to enumerate and explore the resources published by the OData service.
The rules for resource path construction as defined in this section are optional. OData services SHOULD follow the subsequently described URL path construction rules and are indeed encouraged to do so; as such consistency promotes a rich ecosystem of reusable client components and libraries.
Services that do not follow the resource path conventions for entity container children are strongly encouraged to document their resource paths by annotating entity container children with the term Core.ResourcePath defined in [OData-VocCore]. The annotation value is the URL of the annotated resource and may be relative to xml:base (if present), otherwise Content-Location (if present), otherwise the request URL.
Resources exposed by an OData service are addressable by corresponding resource path URL components to enable interaction of the client with that resource aspect.
To illustrate the concept, some examples for resources might be: customers, a single customer, orders related to a single customer, and so forth. Examples of addressable aspects of these resources as exposed by the data model might be: collections of entities, a single entity, properties, links, operations, and so on.
An OData service MAY respond with 301 Moved Permanently or 307 Temporary Redirect from the canonical URL to the actual URL.
OData services expose their entity model according to [OData-CSDL] at the metadata URL, formed by appending $metadata to the service root URL.
Example 5: Metadata document URL
http://host/service/$metadata
OData services MAY expose their entity model as a service, according to [OData-CSDL], by appending a trailing slash (/) to the metadata document URL.
Example 6: Metadata service root URL
http://host/service/$metadata/
OData services that support batch requests expose a batch URL formed by appending $batch to the service root URL.
Example 7: batch URL
http://host/service/$batch
The basic rules for addressing a collection (of entities), a single entity within a collection, a singleton, as well as a property of an entity are covered in the resourcePath syntax rule in [OData-ABNF].
Below is a (non-normative) snippet from [OData-ABNF]:
resourcePath = entitySetName [collectionNavigation]
/ singleton [singleNavigation]
/ actionImportCall
/ entityColFunctionImportCall [ collectionNavigation ]
/ entityFunctionImportCall [ singleNavigation ]
/ complexColFunctionImportCall [ collectionPath ]
/ complexFunctionImportCall [ complexPath ]
/ primitiveColFunctionImportCall [ collectionPath ]
/ primitiveFunctionImportCall [ singlePath ]
/ crossjoin
/ '$all'
Since OData has a uniform composable URL syntax and associated rules there are many ways to address a collection of entities, including, but not limited to:
· Via an entity set (see rule entitySetName in [OData-ABNF])
Example 8:
http://host/service/Products
· By navigating a collection-valued navigation property (see rule: entityColNavigationProperty)
· By invoking a function that returns a collection of entities (see rule: entityColFunctionCall)
Example 9: function with parameters in resource path
http://host/service/ProductsByCategoryId(categoryId=2)
Example 10: function with parameters as query options
http://host/service/ProductsByColor(color=@color)?@color='red'
· By invoking an action that returns a collection of entities (see rule: actionCall)
Likewise there are many ways to address a single entity.
Sometimes a single entity can be accessed directly, for example by:
· Invoking a function that returns a single entity (see rule: entityFunctionCall)
· Invoking an action that returns a single entity (see rule: actionCall)
· Addressing a singleton
Example 11:
http://host/service/BestProductEverCreated
Often however a single entity is accessed by composing more path segments to a resourcePath that identifies a collection of entities, for example by:
· Using an entity key to select a single entity (see rules: collectionNavigation and keyPredicate)
Example 12:
http://host/service/Categories(1)
· Invoking an action bound to a collection of entities that returns a single entity (see rule: boundOperation)
· Invoking an function bound to a collection of entities that returns a single entity (see rule: boundOperation)
Example 13:
http://host/service/Products/Model.MostExpensive()
These rules are recursive, so it is possible to address a single entity via another single entity, a collection via a single entity and even a collection via a collection; examples include, but are not limited to:
· By following a navigation from a single entity to another related entity (see rule: entityNavigationProperty)
Example 14:
http://host/service/Products(1)/Supplier
· By invoking a function bound to a single entity that returns a single entity (see rule: boundOperation)
Example 15:
http://host/service/Products(1)/Model.MostRecentOrder()
· By invoking an action bound to a single entity that returns a single entity (see rule: boundOperation)
· By following a navigation from a single entity to a related collection of entities (see rule: entityColNavigationProperty)
Example 16:
http://host/service/Categories(1)/Products
· By invoking a function bound to a single entity that returns a collection of entities (see rule: boundOperation)
Example 17:
http://host/service/Categories(1)/Model.TopTenProducts()
· By invoking an action bound to a single entity that returns a collection of entities (see rule: boundOperation)
· By invoking a function bound to a collection of entities that returns a collection of entities (see rule: boundOperation)
Example 18:
http://host/service/Categories(1)/Products/Model.AllOrders()
· By invoking an action bound to a collection of entities that returns a collection of entities (see rule: boundOperation)
Finally it is possible to compose path segments onto a resource path that identifies a primitive, complex instance, collection of primitives or collection of complex instances and bind an action or function that returns an entity or collections of entities.
For OData services conformant with the addressing conventions in this section, the canonical form of an absolute URL identifying a non-contained entity is formed by adding a single path segment to the service root URL. The path segment is made up of the name of the entity set associated with the entity followed by the key predicate identifying the entity within the collection. No type-cast segment is added to the canonical URL, even if the entity is an instance of a type derived from the declared entity type of its entity set.
Example 19: Non-canonical URL
http://host/service/Categories(1)/Products(1)
Example 20: Canonical URL for previous example:
http://host/service/Products(1)
For contained entities (i.e. related via a navigation property that specifies ContainsTarget="true", see [OData-CSDL]) the canonical URL is the canonical URL of the containing entity followed by:
· A cast segment if the navigation property is defined on a type derived from the entity type declared for the entity set,
· A path segment for the containment navigation property, and
· If the navigation property returns a collection, a key predicate that uniquely identifies the entity in that collection.
If a navigation property leading to a related entity type has a partner navigation property that specifies a referential constraint, then those key properties of the related entity that take part in the referential constraint MAY be omitted from URLs.
Example 21: full key predicate of related entity
https://host/service/Orders(1)/Items(OrderID=1,ItemNo=2)
Example 22: shortened key predicate of related entity
https://host/service/Orders(1)/Items(2)
The two above examples are equivalent if the navigation property Items from Order to OrderItem has a partner navigation property from OrderItem to Order with a referential constraint tying the value of the OrderID key property of the OrderItem to the value of the ID property of the Order.
The shorter form that does not specify the constrained key parts redundantly is preferred. If the value of the constrained key is redundantly specified then it MUST match the principal key value.
To resolve an entity-id into a representation of the identified entity, the client issues a GET request to the $entity resource located at the URL /$entity relative to the service root URL. The entity-id MUST be specified using the system query option $id. The entity-id may be expressed as an absolute IRI or relative to the service root URL.
Example 23: request the entity representation for an entity-id
http://host/service/$entity?$id=Products(0)
The semantics of $entity are covered in the [OData-Protocol] document.
OData services are based on a data model that supports relationships as first class constructs. For example, an OData service could expose a collection of Products entities each of which are related to a Category entity.
References between entities are addressable in OData just like entities themselves are (as described above) by appending a navigation property name followed by /$ref to the entity URL.
Example 24: URL addressing the references between Categories(1) and Products
http://host/service/Categories(1)/Products/$ref
Resource paths addressing a single entity reference can be used in DELETE requests to unrelated two entities. Resource paths addressing collection of references can be used in DELETE requests if they are followed by the system query option $id identifying one of the entity references in the collection. The entity-id specified by $id may be expressed absolute or relative to the request URL. For details see [OData-Protocol].
Example 25: two ways of unrelating Categories(1) and Products('Bread')
DELETE http://host/service/Categories(1)/Products/$ref?$id=Products('Bread')
DELETE http://host/service/Products('Bread')/Category/$ref
The semantic rules for addressing and invoking actions are defined in the [OData-Protocol] document. The grammar for addressing and invoking actions is defined by the following syntax grammar rules in [OData-ABNF]:
The semantic rules for addressing and invoking functions are defined in the [OData-Protocol] document. The grammar for addressing and invoking functions is defined by a number syntax grammar rules in [OData-ABNF], in particular:
To address an entity property clients append a path segment containing the property name to the URL of the entity. If the property has a complex type value, properties of that value can be addressed by further property name composition.
To address the raw value of a primitive property, clients append a path segment containing the string $value to the property URL.
Properties of type Edm.Stream already return the raw value of the media stream and do not support appending the $value segment.
To address the raw value of the number of items in a collection, clients append the path segment /$count to the URL identifying the entity set or collection.
Example 26: the number of related entities
http://host/service/Categories(1)/Products/$count
Example 27: the number of entities in an entity set
http://host/service/Products/$count
Example 28: entity count in a $filter expression. Note that the spaces around gt are for readability of the example only; in real URLs they must be percent-encoded as %20.
http://host/service/Categories?$filter=Products/$count gt 0
Example 29: entity count in an $orderby expression
http://host/service/Categories?$orderby=Products/$count
Any resource path or path expression identifying a collection of entities or complex type instances can be appended with a path segment containing the qualified name of a type derived from the declared type of the collection. The result will be restricted to instances of the derived type and may be empty.
Any resource path or path expression identifying a single entity or complex type instance can be appended with a path segment containing the qualified name of a type derived from the declared type of the identified resource. If used in a resource path and the identified resource is not an instance of the derived type, the request will result in a 404 Not Found response. If used in a path expression that is part of a Boolean expression, the type cast will evaluate to null.
Example 30: entity set restricted to VipCustomer instances
http://host/service/Customers/Model.VipCustomer
Example 31: entity restricted to a VipCustomer instance, resulting in 404 Not Found if the customer with key 1 is not a VipCustomer
http://host/service/Customers/Model.VipCustomer(1)
http://host/service/Customers(1)/Model.VipCustomer
Example 32: cast the complex property Address to its derived type DetailedAddress, then get a property of the derived type
http://host/service/Customers(1)/Address/Model.DetailedAddress/Location
Example 33: filter expression with type cast; will evaluate to null for all non-VipCustomer instances and thus return only instances of VipCustomer
http://host/service/Customers?
$filter=Model.VipCustomer/PercentageOfVipPromotionProductsOrdered gt 80
Example 34: expand the single related Customer only if it is an instance of Model.VipCustomer. For to-many relationships only Model.VipCustomer instances would be inlined,
http://host/service/Orders?$expand=Customer/Model.VipCustomer
To address the media stream represented by a media entity, clients append a path segment containing the string $value to the media entity URL. Services may redirect from this canonical URL to the source URL of the media stream.
Example 35: request the media stream for the picture with the key value Sunset4321299432:
http://host/service/Pictures('Sunset4321299432')/$value
In addition to querying related entities through navigation properties defined in the entity model of a service, the cross join operator allows querying across unrelated entity sets.
The cross join is addressed by appending the path segment $crossjoin followed by the parenthesized comma-separated list of joined entity sets. It returns the Cartesian product of all the specified entity sets, represented as a collection of instances of a virtual complex type. Each instance consists of one non-nullable, single-valued navigation property per joined entity set. Each such navigation property is named identical to the corresponding entity set, with a target type equal to the declared entity type of the corresponding entity set.
The $filter and $orderby query options can be specified using properties of the entities in the selected entity sets, prepended with the entity set as the navigation property name.
The $expand query option can be specified using the names of the selected entity sets as navigation property names. If a selected entity set is not expanded, it MUST be represented using the read URL of the related entity as a navigation link in the complex type instance.
The $count, $skip, and $top query options can also be used with no special semantics.
Example 36: if Sales had a structural property ProductID instead of a navigation property Product, a “cross join” between Sales and Products could be addressed
http://host/service/$crossjoin(Products,Sales)?
$filter=Products/ID eq Sales/ProductID
The symbolic resource $all identifies the collection of all entities in a service, i.e. the union of all entity sets plus all singletons.
This symbolic resource is of type Collection(Edm.EntityType) and allows the $search system query option plus all other query options applicable to collections of entities.
Example 37: all entities in a service
http://host/service/$all
The query options part of an OData URL specifies three types of information: system query options, custom query options, and parameter aliases. All OData services MUST follow the query string parsing and construction rules defined in this section and its subsections.
System query options are query string parameters that control the amount and order of the data returned for the resource identified by the URL. The names of all system query options are prefixed with a dollar ($) character.
For GET requests the following rules apply:
· Resource paths identifying a single entity, a complex type instance, a collection of entities, or a collection of complex type instances allow $expand and $select.
· Resource paths identifying a collection allow $filter, $count, $orderby, $skip, and $top.
· Resource paths identifying a collection of entities allow $search.
· Resource paths not ending in /$count or /$batch allow $format.
For POST requests to an action URL the return type of the action determines the applicable system query options, following the same rules as GET requests.
POST requests to entity sets as well as all PUT and DELETE requests do not allow system query options.
An OData service may support some or all of the system query options defined. If a data service does not support a system query option, it MUST reject any request that contains the unsupported option.
The semantics of all system query options are defined in the [OData-Protocol] document.
The grammar and syntax rules for system query options are defined in [OData-ABNF].
The $filter system query option allows clients to filter a collection of resources that are addressed by a request URL. The expression specified with $filter is evaluated for each resource in the collection, and only items where the expression evaluates to true are included in the response. Resources for which the expression evaluates to false or to null, or which reference properties that are unavailable due to permissions, are omitted from the response.
The [OData-ABNF] filter syntax rule defines the formal grammar of the $filter query option.
OData defines a set of logical operators that evaluate to true or false (i.e. a boolCommonExpr as defined in [OData-ABNF]). Logical operators are typically used to filter a collection of resources.
Operands of collection, entity, and complex types are not supported in logical operators.
The syntax rules for the logical operators are defined in [OData-ABNF].
The six comparison operators can be used with all primitive values except Edm.Binary, Edm.Stream, and the Geo types.
The eq operator returns true if the left operand is equal to the right operand, otherwise it returns false.
The null value is equal to itself, and only to itself.
The ne operator returns true if the left operand is not equal to the right operand, otherwise it returns false.
The null value is not equal to any value but itself.
The gt operator returns true if the left operand is greater than the right operand, otherwise it returns false.
If any operand is null, the operator returns false.
For Boolean values true is greater than false.
The ge operator returns true if the left operand is greater than or equal to the right operand, otherwise it returns false.
If only one operand is null, the operator returns false. If both operands are null, it returns true because null is equal to itself.
The lt operator returns true if the left operand is less than the right operand, otherwise it returns false.
If any operand is null, the operator returns false.
The le operator returns true if the left operand is less than or equal to the right operand, otherwise it returns false.
If only one operand is null, the operator returns false. If both operands are null, it returns true because null is equal to itself.
The and operator returns true if both the left and right operands evaluate to true, otherwise it returns false.
The null value is treated as unknown, so if one operand evaluates to null and the other operand to false, the and operator returns false. All other combinations with null return null.
The or operator returns false if both the left and right operands both evaluate to false, otherwise it returns true.
The null value is treated as unknown, so if one operand evaluates to null and the other operand to true, the or operator returns true. All other combinations with null return null.
The not operator returns true if the operand returns false, otherwise it returns false.
The null value is treated as unknown, so not null returns null.
The has operator returns true if the right hand operand is an enumeration value whose flag(s) are set on the left operand.
The following examples illustrate the use and semantics of each of the logical operators.
Example 38: all products with a Name equal to 'Milk'
http://host/service/Products?$filter=Name eq 'Milk'
Example 39: all products with a Name not equal to 'Milk'
http://host/service/Products?$filter=Name ne 'Milk'
Example 40: all products with a Name greater than 'Milk':
http://host/service/Products?$filter=Name gt 'Milk'
Example 41: all products with a Name greater than or equal to 'Milk':
http://host/service/Products?$filter=Name ge 'Milk'
Example 42: all products with a Name less than 'Milk':
http://host/service/Products?$filter=Name lt 'Milk'
Example 43: all products with a Name less than or equal to 'Milk':
http://host/service/Products?$filter=Name le 'Milk'
Example 44: all products with the Name 'Milk' that also have a Price less than 2.55:
http://host/service/Products?$filter=Name eq 'Milk' and Price lt '2.55'
Example 45: all products that either have the Name 'Milk' or have a Price less than 2.55:
http://host/service/Products?$filter=Name eq 'Milk' or Price lt 2.55
Example 46: all products that do not have a Name that ends with 'ilk':
http://host/service/Products?$filter=not endswith(Name,'ilk')
OData defines a set of arithmetic operators that require operands that evaluate to numeric types. Arithmetic operators are typically used to filter a collection of resources. However services MAY allow using arithmetic operators with the $orderby system query option.
If an operand of an arithmetic operator is null, the result is null.
The syntax rules for the arithmetic operators are defined in [OData-ABNF].
The add operator adds the left and right numeric operands.
The add operator is also valid for the following time-related operands:
· DateTimeOffset add Duration results in a DateTimeOffset
· Duration add Duration results in a Duration
· Date add Duration results in a DateTimeOffset
The sub operator subtracts the right numeric operand from the left numeric operand.
The sub operator is also valid for the following time-related operands:
· DateTimeOffset sub Duration results in a DateTimeOffset
· Duration sub Duration results in a Duration
· DateTimeOffset sub DateTimeOffset results in a Duration
· Date sub Duration results in a DateTimeOffset
· Date sub Date results in a Duration
The negation operator, represented by a minus (-) sign, changes the sign of its numeric or Duration operand.
The mul operator multiplies the left and right numeric operands.
The div operator divides the left numeric operand by the right numeric operand. If the right operand is zero and the left operand is neither of type Edm.Single nor Edm.Double, the request fails. If the left operand is of type Edm.Single or Edm.Double, then positive div zero returns INF, negative div zero returns -INF, and zero div zero returns = NaN.
The mod operator returns the remainder when the left integral operand is divided by the right integral operand. If the right operand is negative, the sign of the result is the same as the sign of the left operand. If the right operand is zero, the request fails.
The following examples illustrate the use and semantics of each of the Arithmetic operators.
Example 47: all products with a Price of 2.55:
http://host/service/Products?$filter=Price add 2.45 eq 5.00
Example 48: all products with a Price of 2.55:
http://host/service/Products?$filter=Price sub 0.55 eq 2.00
Example 49: all products with a Price of 2.55:
http://host/service/Products?$filter=Price mul 2.0 eq 5.10
Example 50: all products with a Price of 2.55:
http://host/service/Products?$filter=Price div 2.55 eq 1
Example 51: all products with a Rating exactly divisible by 5:
http://host/service/Products?$filter=Rating mod 5 eq 0
The Grouping operator (open and close parenthesis "( )") controls the evaluation order of an expression. The Grouping operator returns the expression grouped inside the parenthesis.
Example 52: all products because 9 mod 3 is 0
http://host/service/Products?$filter=(4 add 5) mod (4 sub 1) eq 0
In addition to operators, a set of functions is also defined for use with the $filter or $orderby system query options. The following sections describe the available functions. Note: ISNULL or COALESCE operators are not defined. Instead, OData defines a null literal that can be used in comparisons.
If a parameter of a canonical function is null, the function returns null.
The syntax rules for all functions are defined in [OData-ABNF].
The contains function has the following signature:
Edm.Boolean contains(Edm.String,Edm.String)
The contains function returns true if the second parameter string value is a substring of the first parameter string value, otherwise it returns false. The containsMethodCallExpr syntax rule defines how the contains function is invoked.
Example 53: all customers with a CompanyName that contains 'Alfreds'
http://host/service/Customers?$filter=contains(CompanyName,'Alfreds')
The endswith function has the following signature:
Edm.Boolean endswith(Edm.String,Edm.String)
The endswith function returns true if the first parameter string value ends with the second parameter string value, otherwise it returns false. The endsWithMethodCallExpr syntax rule defines how the endswith function is invoked.
Example 54: all customers with a CompanyName that ends with 'Futterkiste'
http://host/service/Customers?$filter=endswith(CompanyName,'Futterkiste')
The startswith function has the following signature:
Edm.Boolean startswith(Edm.String,Edm.String)
The startswith function returns true if the first parameter string value starts with the second parameter string value, otherwise it returns false. The startsWithMethodCallExpr syntax rule defines how the startswith function is invoked.
Example 55: all customers with a CompanyName that starts with 'Alfr'
http://host/service/Customers?$filter=startswith(CompanyName,'Alfr')
The length function has the following signature:
Edm.Int32 length(Edm.String)
The length function returns the number of characters in the parameter value. The lengthMethodCallExpr syntax rule defines how the length function is invoked.
Example 56: all customers with a CompanyName that is 19 characters long
http://host/service/Customers?$filter=length(CompanyName) eq 19
The indexof function has the following signature:
Edm.Int32 indexof(Edm.String,Edm.String)
The indexof function returns the zero-based character position of the first occurrence of the second parameter value in the first parameter value. The indexOfMethodCallExpr syntax rule defines how the indexof function is invoked.
Example 57: all customers with a CompanyName containing 'lfreds' starting at the second character
http://host/service/Customers?$filter=indexof(CompanyName,'lfreds') eq 1
The substring function has consists of two overloads, with the following signatures:
Edm.String
substring(Edm.String,Edm.Int32)
Edm.String substring(Edm.String,Edm.Int32,Edm.Int32)
The two argument substring function returns a substring of the first parameter string value, starting at the Nth character and finishing at the last character (where N is the second parameter integer value). The three argument substring function returns a substring of the first parameter string value identified by selecting M characters starting at the Nth character (where N is the second parameter integer value and M is the third parameter integer value).
The substringMethodCallExpr syntax rule defines how the substring functions are invoked.
Example 58: all customers with a CompanyName of 'lfreds Futterkiste' once the first character has been removed
http://host/service/Customers?
$filter=substring(CompanyName, 1) eq 'lfreds
Futterkiste'
Example 59: all customers with a CompanyName that has 'lf' as the second and third characters
http://host/service/Customers?$filter=substring(CompanyName,1,2) eq 'lf'
The tolower function has the following signature:
Edm.String tolower(Edm.String)
The tolower function returns the input parameter string value with all uppercase characters converted to lowercase according to Unicode rules. The toLowerMethodCallExpr syntax rule defines how the tolower function is invoked.
Example 60: all customers with a CompanyName that equals 'alfreds futterkiste' once any uppercase characters have been converted to lowercase
http://host/service/Customers?
$filter=tolower(CompanyName) eq 'alfreds futterkiste'
The toupper function has the following signature:
Edm.String toupper(Edm.String)
The toupper function returns the input parameter string value with all lowercase characters converted to uppercase according to Unicode rules. The toUpperMethodCallExpr syntax rule defines how the toupper function is invoked.
Example 61: all customers with a CompanyName that equals 'ALFREDS FUTTERKISTE' once any lowercase characters have been converted to uppercase
http://host/service/Customers?
$filter=toupper(CompanyName) eq 'ALFREDS FUTTERKISTE'
The trim function has the following signature:
Edm.String trim(Edm.String)
The trim function returns the input parameter string value with all leading and trailing whitespace characters, according to Unicode rules, removed. The trimMethodCallExpr syntax rule defines how the trim function is invoked.
Example 62: all customers with a CompanyName without leading or trailing whitespace characters
http://host/service/Customers?$filter=trim(CompanyName) eq CompanyName
The concat function has the following signature:
Edm.String concat(Edm.String,Edm.String)
The concat function returns a string that appends the second input parameter string value to the first. The concatMethodCallExpr syntax rule defines how the concat function is invoked.
Example 63: all customers from Berlin, Germany
http://host/service/Customers?
$filter=concat(concat(City,', '), Country) eq 'Berlin, Germany'
The year function has the following signatures:
Edm.Int32 year(Edm.Date)
Edm.Int32 year(Edm.DateTimeOffset)
The year function returns the year component of the Date or DateTimeOffset parameter value, evaluated in the time zone of the DateTimeOffset parameter value. The yearMethodCallExpr syntax rule defines how the year function is invoked.
Services that are unable to preserve the offset of Edm.DateTimeOffset values and instead normalize the values to some common time zone (i.e. UTC) MUST fail evaluation of the year function for literal Edm.DateTimeOffset values that are not stated in the time zone of the normalized values.
Example 64: all employees born in 1971
http://host/service/Employees?$filter=year(BirthDate) eq 1971
The month function has the following signatures:
Edm.Int32 month(Edm.Date)
Edm.Int32 month(Edm.DateTimeOffset)
The month function returns the month component of the Date or DateTimeOffset parameter value, evaluated in the time zone of the DateTimeOffset parameter value. The monthMethodCallExpr syntax rule defines how the month function is invoked.
Services that are unable to preserve the offset of Edm.DateTimeOffset values and instead normalize the values to some common time zone (i.e. UTC) MUST fail evaluation of the month function for literal Edm.DateTimeOffset values that are not stated in the time zone of the normalized values.
Example 65: all employees born in May
http://host/service/Employees?$filter=month(BirthDate) eq 5
The day function has the following signatures:
Edm.Int32 day(Edm.Date)
Edm.Int32 day(Edm.DateTimeOffset)
The day function returns the day component Date or DateTimeOffset parameter value, evaluated in the time zone of the DateTimeOffset parameter value. The dayMethodCallExpr syntax rule defines how the day function is invoked.
Services that are unable to preserve the offset of Edm.DateTimeOffset values and instead normalize the values to some common time zone (i.e. UTC) MUST fail evaluation of the day function for literal Edm.DateTimeOffset values that are not stated in the time zone of the normalized values.
Example 66: all employees born on the 8th day of a month
http://host/service/Employees?$filter=day(BirthDate) eq 8
The hour function has the following signatures:
Edm.Int32 hour(Edm.DateTimeOffset)
Edm.Int32 hour(Edm.TimeOfDay)
The hour function returns the hour component of the DateTimeOffset or TimeOfDay parameter value, evaluated in the time zone of the DateTimeOffset parameter value. The hourMethodCallExpr syntax rule defines how the hour function is invoked.
Services that are unable to preserve the offset of Edm.DateTimeOffset values and instead normalize the values to some common time zone (i.e. UTC) MUST fail evaluation of the hour function for literal Edm.DateTimeOffset values that are not stated in the time zone of the normalized values.
Example 67: all employees born in the 4th hour of a day
http://host/service/Employees?$filter=hour(BirthDate) eq 4
The minute function has the following signatures:
Edm.Int32
minute(Edm.DateTimeOffset)
Edm.Int32 minute(Edm.TimeOfDay)
The minute function returns the minute component of the DateTimeOffset or TimeOfDay parameter value, evaluated in the time zone of the DateTimeOffset parameter value. The minuteMethodCallExpr syntax rule defines how the minute function is invoked.
Example 68: all employees born in the 40th minute of any hour on any day
http://host/service/Employees?$filter=minute(BirthDate) eq 40
The second function has the following signatures:
Edm.Int32
second(Edm.DateTimeOffset)
Edm.Int32 second(Edm.TimeOfDay)
The second function returns the second component (without the fractional part) of the DateTimeOffset or TimeOfDay parameter value. The secondMethodCallExpr syntax rule defines how the second function is invoked.
Example 69: all employees born in the 40th second of any minute of any hour on any day
http://host/service/Employees?$filter=second(BirthDate) eq 40
The fractionalseconds function has the following signatures:
Edm.Decimal fractionalseconds(Edm.DateTimeOffset)
Edm.Decimal fractionalseconds(Edm.TimeOfDay)
The fractionalseconds function returns the fractional seconds component of the DateTimeOffset or TimeOfDay parameter value as a non-negative decimal value less than 1. The fractionalsecondsMethodCallExpr syntax rule defines how the fractionalseconds function is invoked.
Example 70: all employees born less than 100 milliseconds after a full second of any minute of any hour on any day
http://host/service/Employees?$filter=fractionalseconds(BirthDate) lt 0.1
The date function has the following signature:
Edm.Date date(Edm.DateTimeOffset)
The date function returns the date part of the DateTimeOffset parameter value, evaluated in the time zone of the DateTimeOffset parameter value.
The time function has the following signature:
Edm.TimeOfDay time(Edm.DateTimeOffset)
The time function returns the time part of the DateTimeOffset parameter value, evaluated in the time zone of the DateTimeOffset parameter value.
Services that are unable to preserve the offset of Edm.DateTimeOffset values and instead normalize the values to some common time zone (i.e. UTC) MUST fail evaluation of the time function for literal Edm.DateTimeOffset values that are not stated in the time zone of the normalized values.
The totaloffsetminutes function has the following signature:
Edm.Int32 totaloffsetminutes(Edm.DateTimeOffset)
The totaloffsetminutes function returns the signed number of minutes in the time zone offset part of the DateTimeOffset parameter value, evaluated in the time zone of the DateTimeOffset parameter value.
The now function has the following signature:
Edm.DateTimeOffset now()
The now function returns the current point in time (date and time with time zone) as a DateTimeOffset value.
Services are free to choose the time zone for the current point, e.g. UTC. Services that are unable to preserve the offset of Edm.DateTimeOffset values and instead normalize the values to some common time zone SHOULD return a value in the normalized time zone (i.e., UTC).
The maxdatetime function has the following signature:
Edm.DateTimeOffset maxdatetime()
The maxdatetime function returns the latest possible point in time as a DateTimeOffset value.
The mindatetime function has the following signature:
Edm.DateTimeOffset mindatetime()
The mindatetime function returns the earliest possible point in time as a DateTimeOffset value.
The totalseconds function has the following signature:
Edm.Decimal totalseconds(Edm.Duration)
The totalseconds function returns the duration of the value in total seconds, including fractional seconds.
The round function has the following signatures
Edm.Double round(Edm.Double)
Edm.Decimal round(Edm.Decimal)
The round function rounds the input numeric parameter to the nearest numeric value with no decimal component. The mid-point between two integers is rounded away from zero, i.e. 0.5 is rounded to 1 and ‑0.5 is rounded to -1. The roundMethodCallExpr syntax rule defines how the round function is invoked.
Example 71: all orders with freight costs that round to 32
http://host/service/Orders?$filter=round(Freight) eq 32
The floor function has the following signatures
Edm.Double floor(Edm.Double)
Edm.Decimal floor(Edm.Decimal)
The floor function rounds the input numeric parameter down to the nearest numeric value with no decimal component. The floorMethodCallExpr syntax rule defines how the floor function is invoked.
Example 72: all orders with freight costs that round down to 32
http://host/service/Orders?$filter=floor(Freight) eq 32
The ceiling function has the following signatures
Edm.Double ceiling(Edm.Double)
Edm.Decimal ceiling(Edm.Decimal)
The ceiling function rounds the input numeric parameter up to the nearest numeric value with no decimal component. The ceilingMethodCallExpr syntax rule defines how the ceiling function is invoked.
Example 73: all orders with freight costs that round up to 32
http://host/service/Orders?$filter=ceiling(Freight) eq 32
The isof function has the following signatures
Edm.Boolean isof(type)
Edm.Boolean isof(expression,type)
The single parameter isof function returns true if the current instance is assignable to the type specified, otherwise it returns false. The two parameter isof function return true if the object referred to by the expression is assignable to the type specified, otherwise it returns false.
The isofExpr syntax rule defines how the isof function is invoked.
Example 74: orders that are also BigOrders
http://host/service/Orders?$filter=isof(NorthwindModel.BigOrder)
Example 75: orders of a customer that is a VIPCustomer
http://host/service/Orders?$filter=isof(Customer,NorthwindModel.VIPCustomer)
The cast function has the following signatures:
Edm.Any cast(type)
Edm.Any cast(expression,type)
The single parameter cast function returns the current instance cast to the type specified. The two-parameter cast function returns the object referred to by the expression cast to the type specified.
The cast function follows these rules:
· The null value can be cast to any type.
· Primitive types are cast to Edm.String or a type definition based on it by using the literal representation used in payloads, and WKT for Geo types. The cast fails if the target type specifies an insufficient MaxLength.
· Numeric primitive types are cast to each other with appropriate rounding. The cast fails if the integer part doesn't fit into target type.
· Edm.DateTimeOffset, Edm.Duration, and Edm.TimeOfDay values can be cast to the same type with a different precision with appropriate rounding.
· Collections are cast item by item.
· Services MAY support structural casting of entities and complex type instances to a derived type, or arbitrary structured type, by assigning values of identically named properties and casting them recursively. The cast fails if one of the property-value casts fails or the target type contains non-nullable properties that have not been assigned a value.
The cast function is optional for primitive values (first three rules).
If the cast fails the cast function returns null.
The geo.distance function has the following signatures:
Edm.Double geo.distance(Edm.GeographyPoint,Edm.GeographyPoint)
Edm.Double geo.distance(Edm.GeometryPoint,Edm.GeometryPoint)
The geo.distance function returns the shortest distance between the two points in the coordinate reference system signified by the two points’ SRIDs.
The geo.intersects function has the following signatures:
Edm.Boolean geo.intersects(Edm.GeographyPoint,Edm.GeographyPolygon)
Edm.Boolean geo.intersects(Edm.GeometryPoint,Edm.GeometryPolygon)
The geo.intersects function returns true if the specified point lies within the interior or on the boundary of the specified polygon, otherwise it returns false.
The geo.length function has the following signatures:
Edm.Double
geo.length(Edm.GeographyLineString)
Edm.Double geo.length(Edm.GeometryLineString)
The geo.length function returns the total length of its line string parameter in the coordinate reference system signified by its SRID.
OData defines two operators that evaluate a Boolean expression on a collection. Both must be prepended with a navigation path that identifies a collection. The argument of a lambda operator is a lambda variable name followed by a colon (:) and a Boolean expression that uses the lambda variable name to refer to properties of the related entities identified by the navigation path.
The any operator applies a Boolean expression to each member of a collection and returns true if the expression is true for any member of the collection, otherwise it returns false. The any operator without an argument returns true if the collection is not empty.
Example 76: all Orders that have any Items with a Quantity greater than 100
http://host/service/Orders?$filter=Items/any(d:d/Quantity gt 100)
The all operator applies a Boolean expression to each member of a collection and returns true if the expression is true for all members of the collection, otherwise it returns false.
Example 77: all Orders that have only Items with a Quantity greater than 100
http://host/service/Orders?$filter=Items/all(d:d/Quantity gt 100)
Primitive literals can appear in the resource path as key property values, and in the query part, for example, as operands in $filter expressions. They are represented according to the primitiveLiteral rule in [OData-ABNF].
Example 78: Date literal
http://host/service/Products?$filter=ReleaseDate gt date'2013-05-24'
Complex literals and collection literals in URLs are represented as JSON objects and arrays according to the arrayOrObject rule in [OData-ABNF].
Note that the special characters {, }, [, ], and " MUST be percent-encoded in URLs although some browsers will accept and pass them on unencoded.
Example 79: collection of string literals
http://host/service/ProductsByColor?colors=["red","green"]
The null literal can be used to compare a value to null, or to pass a null value to a function.
The $it literal can be used in expressions to refer to the current instance of the collection identified by the resource path. It can be used to compare properties of related entities to properties of the current instance in expressions within lambda operators, for example in $filter and $orderby expressions on collections of primitive types, or in $filter expressions nested within $expand.
Example 80: email addresses ending with .com assuming EmailAddresses is a collection of strings
http://host/service/Customers(1)/EmailAddresses?$filter=endswith($it,'.com')
Example 81: customers along with their orders that shipped to the same city as the customer's address. The nested filter expression is evaluated in the context of Orders; $it allows referring to values in the outer context of Customers.
http://host/service/Customers?
$expand=Orders($filter=$it/Address/City eq ShipTo/City)
The $root literal can be used in expressions to refer to resources of the same service. It can be used as a single-valued expression or within complex or collection literals.
Example 82: all employees with the same last name as employee A1235
http://host/service/Employees?
$filter=LastName eq $root/Employees('A1245')/LastName
Example 83: products ordered by a set of customers, where the set of customers is passed as a JSON array containing the resource paths from $root to each customer.
http://host/service/ProductsOrderedBy(Customers=@c)?
@c=[$root/Customers('ALFKI'),$root/Customers('BLAUS')]
Properties and navigation properties of the entity type of the set of resources that are addressed by the request URL can be used as operands or function parameters, as shown in the preceding examples.
Properties of complex properties can be used via the same syntax as in resource paths, i.e. by specifying the name of a complex property, followed by a forward slash / and the name of a property of the complex property, and so on,
Properties and navigation properties of entities related with a target cardinality 0..1 or 1 can be used by specifying the navigation property, followed by a forward slash / and the name of a property of the related entity, and so on.
If a complex property is null, or no entity is related (in case of target cardinality 0..1), its value, and the values of its components, are treated as null.
Example 84: similar behavior whether HeadquarterAddress is a nullable complex type or a nullable navigation property
Companies(1)/HeadquarterAddress/Street
Properties of derived types can be used by specifying the qualified name of a derived type, followed by a forward slash / and the name of the property of the derived type, see addressing derived types. If the current instance is not of the specified derived type, the path expression returns null.
Parameter aliases can be used within $filter or $orderby in place of expressions that evaluate to a primitive value, a complex value, or a collection of primitive or complex values. Parameter names start with the at sign (@) and can be used in more than one place in the expression. The value for the parameter alias is supplied in a query option with the same name as the parameter.
Example 85:
http://host/service/Movies?$filter=contains(@word,Title)&@word='Black'
Example 86:
http://host/service/Movies?$filter=Title eq @title&@title='Wizard of Oz'
OData services MUST use the following operator precedence for supported operators when evaluating $filter and $orderby expressions. Operators are listed by category in order of precedence from highest to lowest. Operators in the same category have equal precedence:
Group |
Operator |
Description |
ABNF Expression |
Grouping |
( ) |
Precedence grouping |
parenExpr boolParenExpr |
Primary |
/ |
Navigation |
firstMemberExpr memberExpr |
|
xxx( ) |
Method Call |
methodCallExpr boolMethodCallExpr functionExpr |
Unary |
- |
Negation |
negateExpr |
|
Not |
Logical Negation |
notExpr |
|
cast( ) |
Type Casting |
castExpr |
Multiplicative |
Mul |
Multiplication |
mulExpr |
|
Div |
Division |
divExpr |
|
Mod |
Modulo |
modExpr |
Additive |
Add |
Addition |
addExpr |
|
Sub |
Subtraction |
subExpr |
Relational |
Gt |
Greater Than |
gtExpr |
|
Ge |
Greater than or Equal |
geExpr |
|
Lt |
Less Than |
ltExpr |
|
Le |
Less than or Equal |
leExpr |
|
isof |
Type Testing |
isofExpr |
Equality |
Eq |
Equal |
eqExpr |
|
Ne |
Not Equal |
neExpr |
Conditional AND |
And |
Logical And |
andExpr |
Conditional OR |
Or |
Logical Or |
orExpr |
Services MAY support numeric promotion for arithmetic operations or when comparing two operands of comparable types by applying the following rules, in order:
1. If either operand is Edm.Double, the other operand is converted to type Edm.Double.
2. Otherwise, if either operand is Edm.Single, the other operand is converted to type Edm.Single.
3. Otherwise, if either operand is of type Edm.Decimal, the other operand is converted to Edm.Decimal.
4. Otherwise, if either operand is Edm.Int64, the other operand is converted to type Edm.Int64.
5. Otherwise, if either operand is Edm.Int32, the other operand is converted to type Edm.Int32
6. Otherwise, if either operand is Edm.Int16, the other operand is converted to type Edm.Int16.
Each of these promotions uses the same semantics as a castExpression to promote an operand to the target type.
If the result of an arithmetic operation does not fit into the type determined by the above rules, the next-wider type is used in the above order, with Edm.Double considered widest.
OData does not define an implicit conversion between string and numeric types.
The $expand system query option specifies the related resources to be included in line with retrieved resources.
What follows is a (non-normative) snippet from [OData-ABNF] that describes the syntax of $expand:
expand = '$expand' EQ expandItem *( COMMA expandItem )
expandItem = STAR [ ref / OPEN levels CLOSE ]
/ expandPath
[ ref [ OPEN expandRefOption
*( SEMI expandRefOption ) CLOSE ]
/ count [ OPEN expandCountOption
*( SEMI expandCountOption ) CLOSE ]
/ OPEN expandOption
*( SEMI expandOption ) CLOSE
]
expandPath = [ qualifiedEntityTypeName "/"
]
*( ( complexProperty / complexColProperty ) "/"
[ qualifiedComplexTypeName "/" ] )
navigationProperty
[ "/" qualifiedEntityTypeName ]
expandCountOption = filter
/ search
expandRefOption = expandCountOption
/ orderby
/ skip
/ top
/ inlinecount
expandOption = expandRefOption
/ select
/ expand
/ levels
Each expandItem is evaluated relative to the entity containing the navigation property being expanded.
A type cast using the qualifiedEntityTypeName to a type containing the property is required in order to expand a navigation property defined on a derived type.
An arbitrary number of single- or collection-valued complex properties, optionally followed by a type cast, allow drilling into complex properties.
The navigationProperty segment MUST identify a navigation property defined on the entity type of the request, the derived entity type specified in the type cast, or the last complex type identified by the complex property path.
Example 87: expand a navigation property of an entity type
http://host/service/Products?$expand=Category
Example 88: expand a navigation property of a complex type
http://host/service/Customers?$expand=Addresses/Country
A navigation property MUST NOT appear in more than one expandItem.
Query options can be applied to the expanded navigation property by appending a semicolon-separated list of query options, enclosed in parentheses, to the navigation property name.
http://host/service/Categories?
$expand=Products($filter=DiscontinuedDate eq null)
Allowed system query options are $filter, $select, $orderby, $skip, $top, $count, $search, and $expand.
To retrieve entity references instead of the related entities, append /$ref to the navigation property name or type-cast segment following a navigation property name.
Example 89: all categories and for each category the references of all related products
http://host/service/Categories?$expand=Products/$ref
Example 90: all categories and for each category the references of all related products of the derived type Sales.PremierProduct
http://host/service/Categories?$expand=Products/Sales.PremierProduct/$ref
Example 91: all categories and for each category the references of all related premier products with a current promotion equal to null
http://host/service/Categories?
$expand=Products/Sales.PremierProduct/$ref($filter=CurrentPromotion eq
null)
Cyclic navigation properties (whose target type is identical or can be cast to its source type) can be recursively expanded using the special $levels option. The value of the $levels option is either a positive integer to specify the number of levels to expand, or the literal string max to specify the maximum expansion level supported by that service.
Example 92: all employees with their manager, manager's manager, and manager's manager's manager
http://host/service/Employees?$expand=Model.Manager/DirectReports($levels=3)
It is also possible to expand all declared and dynamic navigation properties using a star (*). To retrieve references to all related entities use */$ref, and to expand all related entities with a certain distance use the star operator with the $levels option. The star operator can be combined with explicitly named navigation properties, which take precedence over the star operator.
Example 93: expand Supplier and include references for all other related entities
http://host/service/Categories?$expand=*/$ref,Supplier
Example 94: expand all related entities and their related entities
http://host/service/Categories?$expand=*($levels=2)
The $select system query option allows clients to requests a limited set of properties for each entity or complex type.
The $select query option is often used in conjunction with the $expand system query option, to define the extent of the resource graph to return ($expand) and then specify a subset of properties for each resource in the graph ($select). Expanded navigation properties MUST be returned, even if they are not specified as a selectItem.
What follows is a (non-normative) snippet from [OData-ABNF] showing the syntax of $select:
select = '$select' EQ selectItem *( COMMA selectItem )
selectItem = STAR
/ allOperationsInSchema
/ [ qualifiedEntityTypeName "/" ]
( selectProperty
/ qualifiedActionName
/ qualifiedFunctionName
)
selectProperty = primitiveProperty
/ primitiveColProperty
/ navigationProperty
/ selectPath [ "/" selectProperty ]
selectPath = ( complexProperty / complexColProperty )
[ "/" qualifiedComplexTypeName ]
The $select system query option is interpreted relative to the entity type or complex type of the resources identified by the resource path section of the URL. Each selectItem in the $select clause indicates that the response MUST include the declared or dynamic properties, actions and functions identified by that selectItem. The simplest form of a selectItem explicitly requests a property defined on the entity type of the resources identified by the resource path section of the URL.
Example 95: rating and release date of all products
http://host/service/Products?$select=Rating,ReleaseDate
It is also possible to request all declared and dynamic structural properties using a star (*).
Example 96: all structural properties of all products
http://host/service/Products?$select=*
If the selectItem is a navigation property then the corresponding navigation link is represented in the response. If the navigation property also appears in an $expand query option then it is additionally represented as inline content. This inline content can itself be restricted with a nested $select query option, see section 5.1.1.10.
Example 97: name and description of all products, plus name of expanded category
http://host/service/Products?
$select=Name,Description&$expand=Category($select=Name)
Qualifying the selectItem with a qualifiedEntityTypeName prefix casts the entity or complex value to the specified type in order to select a property of that derived type.
A selectItem that is a complex type or collection of complex type can be followed by a forward slash, an optional type cast segment, and the name of a property of the complex type (and so on for nested complex types).
Example 98: the AccountRepresentative property of any supplier that is of the derived type Namespace.PreferredSupplier, together with the Street property of the complex property Address, and the Location property of the derived complex type Namespace.AddressWithLocation
http://host/service/Suppliers?
$select=Namespace.PreferredSupplier/AccountRepresentative,
Address/Street,
Address/Namespace.AddressWithLocation/Location
Any structural property, non-expanded navigation property, or operation not requested as a selectItem (explicitly or via a star) SHOULD be omitted from the response.
If any selectItem (including a star) is specified, actions and functions SHOULD be omitted unless explicitly requested using a qualifiedActionName, a qualifiedFunctionName or the allOperationsInSchema.
If an action or function is requested as a selectItem, either explicitly by using a qualifiedActionName or qualifiedFunctionName cause, or implicitly by using allOperationsInSchema, then the service includes information about how to invoke that operation for each entity identified by the last path segment in the request URL for which the operation can be bound.
If an action or function is requested in a selectItem using a qualifiedActionName or a qualifiedFunctionName and that operation cannot be bound to the entities requested, the service MUST ignore the selectItem.
Example 99: the ID property, the ActionName action defined in Model and all actions and functions defined in the Model2 for each product if those actions and functions can be bound to that product
http://host/service/Products?$select=ID,Model.ActionName,Model2.*
When multiple selectItems exist in a select clause, then the total set of properties, open properties, navigation properties, actions and functions to be returned is equal to the union of the set of those identified by each selectItem.
If a selectItem is a path expression requesting a component of a complex property and the complex property is null on an instance, then the component is treated as null as well.
The $orderby system query option allows clients to request resources in a particular order.
The semantics of $orderby are covered in the [OData-Protocol] document.
The [OData-ABNF] orderby syntax rule defines the formal grammar of the $orderby query option.
The $top system query option requests the number of items in the queried collection to be included in the result. The $skip query option requests the number of items in the queried collection that are to be skipped and not included in the result. A client can request a particular page of items by combining $top and $skip.
The semantics of $top and $skip are covered in the [OData-Protocol] document. The [OData-ABNF] top and skip syntax rules define the formal grammar of the $top and $skip query options respectively.
The $count system query option allows clients to request a count of the matching resources included with the resources in the response. The $count query option has a Boolean value of true or false.
The semantics of $count is covered in the [OData-Protocol] document.
The $search system query option allows clients to request entities matching a free-text search expression.
The $search query option can be applied to a URL representing a collection of entities to return all matching entities within the collection. Applying the $search query option to the $all resource requests all matching entities in the service.
If both $search and $filter are applied to the same request, the results include only those entities that match both criteria.
The [OData-ABNF] search syntax rule defines the formal grammar of the $search query option.
Example 100: all products that are blue or green. It is up to the service to decide what makes a product blue or green.
http://host/service/Products?$search=blue OR green
Search expressions are used within the $search system query option to request entities matching the specified expression.
Terms can be any single word to be matched within the expression.
Terms enclosed in double-quotes comprise a phrase.
Each individual term or phrase comprises a Boolean expression that returns true if the term or phrase is matched, otherwise false. The semantics of what is considered a match is dependent upon the service.
Expressions enclosed in parenthesis comprise a group expression.
The search expression can contain any number of terms, phrases, or group expressions, along with the case-sensitive keywords NOT, AND, and OR, evaluated in that order.
Expressions prefaced with NOT evaluate to true if the expression is not matched, otherwise false.
Two expressions not enclosed in quotes and separated by a space are equivalent to the same two expressions separated by the AND keyword. Such expressions evaluate to true if both of the expressions evaluate to true, otherwise false.
Expressions separated by an OR evaluate to true if either of the expressions evaluate to true, otherwise false.
The [OData-ABNF] searchExpr syntax rule defines the formal grammar of the search expression.
The $format system query option allows clients to request a response in a particular format and is useful for clients without access to request headers for standard content-type negotiation. Where present $format takes precedence over standard content-type negotiation.
The semantics of $format is covered in the [OData-Protocol] document.
The [OData-ABNF] format syntax rule define the formal grammar of the $format query option.
Custom query options provide an extensible mechanism for service-specific information to be placed in a URL query string. A custom query option is any query option of the form shown by the rule customQueryOption in [OData-ABNF].
Custom query options MUST NOT begin with a $ or @ character.
Example 101: service-specific custom query option debug-mode
http://host/service/Products?debug-mode=true
Parameter aliases can be used in place of literal values in function parameters or within a $filter or $orderby expression.
Parameter aliases MUST start with an @ character.
The semantics of function parameter aliases are covered in [OData-Protocol].
The [OData-ABNF] rule aliasAndValue defines the formal grammar for passing function parameter aliases as query options.
The conformance requirements for OData clients and services are described in [OData-Protocol].
The contributions of the OASIS OData Technical Committee members, enumerated in [OData-Protocol], are gratefully acknowledged.
Revision |
Date |
Editor |
Changes Made |
Working Draft 01 |
2012-08-22 |
Michael Pizzo |
Translated Contribution to OASIS format/template |
Committee Specification Draft 01 |
2013-04-26 |
Ralf Handl Michael Pizzo Martin Zurmuehl |
Added FullText Search, modified expand syntax, expand options, crosstabs, enumerations Fleshed out descriptions and examples and addressed numerous editorial and technical issues processed through the TC Added Conformance section |
Committee Specification Draft 02 |
2013-07-01 |
Ralf Handl Michael Pizzo Martin Zurmuehl |
Described which query options are applicable to which resource types and HTTP methods Simplified URL syntax Extended expand with a STAR operator Added special resources for cross-service search, cross joins, resolution of entity-ids Described handling of null values, division by zero, and overflow in arithmetic operations Added filtering for collections of complex and primitive types |