Create entities with one-way links between them

[mjstrasser]

I am trying to create an entity that links to existing entities by posting JSON. The issue appears to be with entities having only one-way links between them.

The OfferedDivision entity has a 1:1 link with the Division entity. Simplified Java sources:

@EdmEntityType(namespace = "TEST")
@EdmEntitySet(name = "Divisions")
public class Division {

  @EdmKey @EdmProperty(name = "DivisionID")
  private String divisionID;

  @EdmProperty(name = "Name")
  private String name;

  // etc.
}

@EdmEntityType(namespace = "TEST")
@EdmEntitySet(name = "OfferedDivisions")
public class OfferedDivision {

  @EdmKey @EdmProperty(name = "OfferedDivisionID")
  private String offeredDivisionID;

  @EdmProperty(name = "OfferDetails")
  private String offerDetails;

  @EdmNavigationProperty(name = "Division")
  private Division division;

  // etc.
}

I have posted a Division entity to /Test.svc/Divisions with:

{
  "DivisionID": "01",
  "Name": "Electricity"
}

I now want to post another entity that links to it, at /Test.svc/OfferedDivisions with:

{
  "OfferedDivisionID": "01",
  "OfferDetails": "Standard Offer",
  "Division": {
    "__metadata": {
      "uri": "Divisions('01')"
    }
  }
}

But it doesn't work. The error message includes:

Caused by: org.apache.olingo.odata2.janos.processor.core.util.AnnotationRuntimeException: Missing source field for related data (sourceStore='org.apache.olingo.odata2.janos.processor.core.data.store.InMemoryDataStore@b67a66', targetStore='org.apache.olingo.odata2.janos.processor.core.data.store.InMemoryDataStore@27a933c9').
at org.apache.olingo.odata2.janos.processor.core.data.source.AnnotationDataSource.writeRelation(AnnotationDataSource.java:321)
at org.apache.olingo.odata2.janos.processor.core.DataSourceProcessor.createInlinedEntities(DataSourceProcessor.java:1151)
at org.apache.olingo.odata2.janos.processor.core.DataSourceProcessor.createEntity(DataSourceProcessor.java:324)

[mjstrasser]

I get the same error when trying to create two entities in one post, such as:

{
  "OfferedDivisionID": "01",
  "OfferDetails": "Standard Offer",
  "Division": {
    "DivisionID": "01",
    "Name": "Electricity"
  }
}

I think that AnnotationDataSource.writeRelation is misusing the information it gets from AnnotationHelper.getCommonNavigationInfo. I am trying to understand this code better.

[mjstrasser]

The exception only occurs if an entity A has navigation to entity B but the latter does not have a 1-to-many navigation back to entity A.

In my example, if Division class included the following field then I would not see this error:

    @EdmNavigationProperty(name = "OfferedDivisions", toMultiplicity = Multiplicity.MANY)
    private List<OfferedDivision> offeredDivisions = new ArrayList<>();

BUT one-way links like this are valid in OData and I am copying an existing schema so I can’t add extra navigation.

I have demonstrated this in the OneWayNavigationBetweenEntities branch of my fork of this repo. The new test entity class Closet has a link to Building but that latter does not have a list of closets.

[mjstrasser]

I have been working on the issue of one-way navigation and have what I believe is a working solution in the NavigationFixes branch of my fork of this repo.

I have re-defined the meaning of isBiDirectional. In the code it did not mean two-way navigation as I had supposed, but actually meant one-way navigation from the target class to the source class, in a call to AnnotationHelper.getCommonNavigationInfo(sourceClass, targetClass). In my definition, it means that the source class has a navigation property to the target class and the target class has a navigation property back to the source class.

• The document EntityNavigation.md illustrates these meanings and how the AnnotatedNavInfo class now behaves.
• The unit-test class AnnotationHelperTest includes tests that show this behaviour.

All existing tests pass.

[mibo]

Hi @mjstrasser,

Thanks a lot for the whole work (investigation and fix) around this issue.
If it is okay for you I will squash and merge it into the master branch.
Otherwise if you have any objections please let me know.

Thanks, mibo

[mjstrasser]

Hi @mibo

Please go ahead with your merge. My work has taken me in other directions over the past year and I am quite out of touch with OData now.

I am pleased my efforts have been useful.

Cheers
Michael