[ODATA-839] A recursive hierarchy annotation may also contain a navigation property to the children nodes - OASIS Technical Committees Issue Tracker

Details

Type: Improvement
Status: Closed
Priority: Major
Resolution: Fixed
Affects Version/s: V4.0_CSD03
Fix Version/s: V4.0_CSD04
Component/s: Data Aggregation
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Environment:

Applied

Proposal:
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Extend the RecursiveHierarchy term by a property ChildrenNavigationProperty }}of type {{Edm.NavigationPropertyPath. Added element with yellow background:

<ComplexType Name="RecursiveHierarchyType"> <Property Type="Edm.PropertyPath" Name="NodeProperty" Nullable="false"> <Annotation Term="Core.Description" String="Property holding the hierarchy node value"/> </Property> <Property Type="Edm.NavigationPropertyPath" Name="ParentNavigationProperty" Nullable="false"> <Annotation Term="Core.Description" String="Property for navigating to the parent node"/> </Property>

<Property Type="Edm.NavigationPropertyPath" Name="ChildrenNavigationProperty" Nullable="true"> <Annotation Term="Core.Description" String="Property for navigating to the children nodes"/> </Property>

<Property Type="Edm.PropertyPath" Name="DistanceFromRootProperty" Nullable="true"> <Annotation Term="Core.Description" String="Property holding the number of edges between the node and the root node"/> </Property> <Property Type="Edm.PropertyPath" Name="IsLeafProperty" Nullable="true"> <Annotation Term="Core.RequiresType" String="Edm.Boolean"/> <Annotation Term="Core.Description" String="Property indicating whether the node is a leaf of the hierarchy"/> </Property> </ComplexType>
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Extend the RecursiveHierarchy term by a property ChildrenNavigationProperty }}of type {{Edm.NavigationPropertyPath . Added element with yellow background: <ComplexType Name= "RecursiveHierarchyType" > <Property Type= "Edm.PropertyPath" Name= "NodeProperty" Nullable= "false" > <Annotation Term= "Core.Description" String= "Property holding the hierarchy node value" /> </Property> <Property Type= "Edm.NavigationPropertyPath" Name= "ParentNavigationProperty" Nullable= "false" > <Annotation Term= "Core.Description" String= "Property for navigating to the parent node" /> </Property> <Property Type= "Edm.NavigationPropertyPath" Name= "ChildrenNavigationProperty" Nullable= "true" > <Annotation Term= "Core.Description" String= "Property for navigating to the children nodes" /> </Property> <Property Type= "Edm.PropertyPath" Name= "DistanceFromRootProperty" Nullable= "true" > <Annotation Term= "Core.Description" String= "Property holding the number of edges between the node and the root node" /> </Property> <Property Type= "Edm.PropertyPath" Name= "IsLeafProperty" Nullable= "true" > <Annotation Term= "Core.RequiresType" String= "Edm.Boolean" /> <Annotation Term= "Core.Description" String= "Property indicating whether the node is a leaf of the hierarchy" /> </Property> </ComplexType>
Resolution:

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https://github.com/oasis-tcs/odata-vocabularies/pull/74

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https://github.com/oasis-tcs/odata-vocabularies/pull/74

Description

Consider a client processing entities according to their hierarchical structure imposed by the given hierarchy annotation.

If the client wants to retrieve the descendants for the next three levels, this could be accomplished with a single request that makes use of a (cyclic) navigation property pointing to the children of a node. Assuming this navigation property has name childrenNodes, and the corresponding navigation property annotated as ParentNavigationProperty has name parentNode, the request would be:

GET set(nodeId)?$expand=childrenNodes($levels=3;$select=parentNode/nodeId,nodeId)

In order to let clients detect the availability of such navigations, the existing RecursiveHierarchy term needs to be Extended as proposed.

A recursive hierarchy annotation may also contain a navigation property to the children nodes

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