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Difference between revisions of "EclipseLink/Development/Dynamic/RefactorPhaseIForSparseMerge"
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| − | If this representation of Employee 1111 were to be marshalled into an object, most fields (<code>ename</code>, <code>mgr</code>, etc.) will contain <code>null</code>. Any attempt to merge this with a version | + | If this representation of Employee 1111 were to be marshalled into an object, most fields (<code>ename</code>, <code>mgr</code>, etc.) will contain <code>null</code>. Any attempt to merge this with a version retrieved from the database would *over-write* committed data with nulls. Because of this, the complete <i>instance</i> must be specified: |
<source lang="xml"> | <source lang="xml"> | ||
<srvc:theInstance> | <srvc:theInstance> | ||
Revision as of 14:46, 18 March 2010
Sparse Merge
Current status
The current DBWS implementation (as of 10/02/18) does not handle SOAP update messages that contain changed-only information. The Update operation (part of CRUD lifecycle) requires 'theInstance' to be fully specified in the SOAPMessage; it would be useful to support an update where - excluding PK fields - only the changed elements are specified
For example, Employee 1111 is assigned a new job 'Dog walker':
<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"> <env:Header/> <env:Body> <srvc:update_empType xmlns:srvc="urn:empService" xmlns:ns1="urn:emp"> <srvc:theInstance> <ns1:empType> <ns1:empno>1111</ns1:empno> <- primary key <ns1:job>Dog walker</ns1:job> <- updated job title </ns1:empType> </srvc:theInstance> </srvc:update_empType> </env:Body> </env:Envelope>
If this representation of Employee 1111 were to be marshalled into an object, most fields (ename, mgr, etc.) will contain null. Any attempt to merge this with a version retrieved from the database would *over-write* committed data with nulls. Because of this, the complete instance must be specified:
<srvc:theInstance> <ns1:empType> <ns1:empno>1111</ns1:empno> <- primary key <ns1:ename>NORMAN</ns1:ename> <ns1:job>Dog walker</ns1:job> <- only field that changed <ns1:mgr>7698</ns1:mgr> <ns1:hiredate>1998-09-08T00:00:00.0</ns1:hiredate> <ns1:sal>10</ns1:sal> <ns1:comm>0.1</ns1:comm> <ns1:deptno xsi:nil="true"/> </ns1:empType> </srvc:theInstance>
Note the use of xsi:nil to indicate null for our Dog walker's department.
DynamicEntity Refactor (Phase I)
The DynamicEntity interface allows one to tell the difference between 'the value was never set' and 'the value is currently null' using public boolean isSet(String propertyName)