Package com.sap.olingo.jpa.processor.core.query

Class JPAExpandJoinQuery

java.lang.Object

com.sap.olingo.jpa.processor.core.query.JPAAbstractQuery

com.sap.olingo.jpa.processor.core.query.JPAAbstractJoinQuery

com.sap.olingo.jpa.processor.core.query.JPAExpandJoinQuery

All Implemented Interfaces:

JPAQuery

public final class JPAExpandJoinQuery
extends JPAAbstractJoinQuery

A query to retrieve the expand entities.

According to OData Version 4.0 Part 2 - 5.1.2 System Query Option $expand the following query options are allowed:

• expandCountOption = filter/ search

• expandRefOption = expandCountOption/ orderby / skip / top / inlinecount
• expandOption = expandRefOption/ select/ expand / levels

As of now only the bold once are supported

Author:

Oliver Grande

Field Summary

Fields inherited from class com.sap.olingo.jpa.processor.core.query.JPAAbstractJoinQuery

ALIAS_SEPERATOR, context, cq, lastInfo, navigationInfo, page, requestContext, root, target, uriResource

Fields inherited from class com.sap.olingo.jpa.processor.core.query.JPAAbstractQuery

cb, claimsProvider, debugger, em, groups, jpaEntity, locale, odata, sd, SELECT_ALL, SELECT_ITEM_SEPERATOR

Constructor Summary

Constructors

Constructor	Description
JPAExpandJoinQuery(org.apache.olingo.server.api.OData odata, JPAODataCRUDContextAccess context, com.sap.olingo.jpa.metadata.core.edm.mapper.api.JPAAssociationPath assoziation, com.sap.olingo.jpa.metadata.core.edm.mapper.api.JPAEntityType entityType, Map<String,List<String>> requestHeaders, JPAODataRequestContextAccess requestContext)
JPAExpandJoinQuery(org.apache.olingo.server.api.OData odata, JPAODataCRUDContextAccess sessionContext, JPAInlineItemInfo item, Map<String,List<String>> requestHeaders, JPAODataRequestContextAccess requestContext, Optional<JPAKeyBoundary> keyBoundary)

Method Summary

Modifier and Type	Method	Description
protected Set<com.sap.olingo.jpa.metadata.core.edm.mapper.api.JPAPath>	buildSelectionPathList(org.apache.olingo.server.api.uri.UriInfoResource uriResource)	Creates the path to all properties that need to be selected from the database.
protected List<javax.persistence.criteria.Selection<?>>	createSelectClause(Map<String,javax.persistence.criteria.From<?,?>> joinTables, Collection<com.sap.olingo.jpa.metadata.core.edm.mapper.api.JPAPath> jpaPathList, javax.persistence.criteria.From<?,?> target, List<String> groups)	The value of the $select query option is a comma-separated list of properties, qualified action names, qualified function names, the star operator (*), or the star operator prefixed with the namespace or alias of the schema in order to specify all operations defined in the schema.
JPAExpandQueryResult	execute()	Process a expand query, which may contains a $skip and/or a $top option.

Methods inherited from class com.sap.olingo.jpa.processor.core.query.JPAAbstractJoinQuery

addTopSkip, buildEntityPathList, buildSelectionAddNavigationAndSelect, createBoundary, createFromClause, createKeyWhere, createProtectionWhere, createWhere, determineAssoziation, determineLastInfo, determineTargetIsCollection, expandPath, extractDescriptionAttributes, generateCollectionAttributeJoin, getLocale, getQuery, getRoot

Methods inherited from class com.sap.olingo.jpa.processor.core.query.JPAAbstractQuery

addWhereClause, createJoinFromPath, createProtectionWhereForEntityType, createWhereByKey, generateDesciptionJoin, getDebugger, orWhereClause

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

JPAExpandJoinQuery

public JPAExpandJoinQuery(org.apache.olingo.server.api.OData odata,
 JPAODataCRUDContextAccess sessionContext,
 JPAInlineItemInfo item,
 Map<String,List<String>> requestHeaders,
 JPAODataRequestContextAccess requestContext,
 Optional<JPAKeyBoundary> keyBoundary)
                   throws org.apache.olingo.commons.api.ex.ODataException

Throws:

org.apache.olingo.commons.api.ex.ODataException

JPAExpandJoinQuery

public JPAExpandJoinQuery(org.apache.olingo.server.api.OData odata,
 JPAODataCRUDContextAccess context,
 com.sap.olingo.jpa.metadata.core.edm.mapper.api.JPAAssociationPath assoziation,
 com.sap.olingo.jpa.metadata.core.edm.mapper.api.JPAEntityType entityType,
 Map<String,List<String>> requestHeaders,
 JPAODataRequestContextAccess requestContext)
                   throws org.apache.olingo.commons.api.ex.ODataException

Throws:

org.apache.olingo.commons.api.ex.ODataException

Method Details

execute

public JPAExpandQueryResult execute()
                             throws org.apache.olingo.server.api.ODataApplicationException

Process a expand query, which may contains a $skip and/or a $top option.

This is a tricky problem, as it can not be done easily with SQL. It could be that a database offers special solutions. There is an worth reading blog regards this topic: How to select the first/least/max row per group in SQL. Often databases offer the option to use ROW_NUMBER together with OVER ... ORDER BY see e.g. SQL ROW_NUMBER. Unfortunately this is not supported by JPA.

Returns:

query result

Throws:

org.apache.olingo.server.api.ODataApplicationException

createSelectClause

protected List<javax.persistence.criteria.Selection<?>> createSelectClause(Map<String,javax.persistence.criteria.From<?,?>> joinTables,
 Collection<com.sap.olingo.jpa.metadata.core.edm.mapper.api.JPAPath> jpaPathList,
 javax.persistence.criteria.From<?,?> target,
 List<String> groups)
                                                                    throws org.apache.olingo.server.api.ODataApplicationException

Description copied from class: JPAAbstractJoinQuery

The value of the $select query option is a comma-separated list of properties, qualified action names, qualified function names, the star operator (*), or the star operator prefixed with the namespace or alias of the schema in order to specify all operations defined in the schema. See: OData Version 4.0 Part 1 - 11.2.4.1 System Query Option $select

See also: OData Version 4.0 Part 2 - 5.1.3 System Query Option $select

Overrides:

createSelectClause in class JPAAbstractJoinQuery

Returns:

Throws:

org.apache.olingo.server.api.ODataApplicationException

buildSelectionPathList

protected Set<com.sap.olingo.jpa.metadata.core.edm.mapper.api.JPAPath> buildSelectionPathList(org.apache.olingo.server.api.uri.UriInfoResource uriResource)
                                                                                       throws org.apache.olingo.server.api.ODataApplicationException

Description copied from class: JPAAbstractJoinQuery

Creates the path to all properties that need to be selected from the database. A Property can be included for the following reasons:

• It is a key in order to be able to build the links
• It is part of the $select system query option
• It is the result of a navigation, which my be restricted by a $select
• If is required to link $expand with result with the parent result
• A stream is requested and the property contains the mime type

Not included are collection properties.

Overrides:

buildSelectionPathList in class JPAAbstractJoinQuery

Returns:

Throws:

org.apache.olingo.server.api.ODataApplicationException