[jira] [Created] (OLINGO-1420) Unable to perform deep insert using Olingo V2 when navigation properties relationship is 1:N

["Slavomír Bavala (Jira)" <ji...@apache.org>]

Slavomír Bavala created OLINGO-1420:
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             Summary: Unable to perform deep insert using Olingo V2 when navigation properties relationship is 1:N
                 Key: OLINGO-1420
                 URL: https://issues.apache.org/jira/browse/OLINGO-1420
             Project: Olingo
          Issue Type: Bug
          Components: odata2-core
    Affects Versions: V2 2.0.11
            Reporter: Slavomír Bavala


Use case: perform deep insert using Olingo V2

As described in https://issues.apache.org/jira/browse/OLINGO-1401 Olingo will not serialize navigation properties and their contents into the request if _contentOnly_ flag is set to *true*.

We set it to *false* but that adds metadata to the request payload as a result. In case of an update, where key properties are not present in the payload but in the URL, the metadata generation will fail (we wrote a hack to overcome this).

The biggest problem we found is the serialization of +_childNavigationProperty_+ properties described by 1:N relationship, see the following example:
{code:java}
{
  "rootLevelProperty": "",
  "rootLevelNavigationProperty": [
    {
      "child": "1",
      "childNavigationProperty": [
         {
           "grandChild": "X"
         }
       ]
    },
    {
      "child": "2",
      "childNavigationProperty": [ 
        { 
          "grandChild": "Y" 
        }
      ]
    }
  }
}{code}
To serialize the navigation properties we need to specify the _customExpanedLinks_ for every nested level. We also need to specify _callbacks_ for every navigation property (this means also defining nested callbacks for nested navigation properties).

When navigation property is described by 1:N relationship, we need to register a _OnWriteFeedContent_ callback. This callback however doesn't allow us to specify nested callbacks for every item in the list, we can only register a single callback for the +*entire feed*+. This means we are not able to serialize _grandChild_ property correctly and we have to choose either "X" or "Y" as a value for both items.

Our code looks like this:
{code:java}
writeEntry(APPLICATION_JSON, rootEntitySet, dataMap,
        serviceRoot(new URI(entitySetName))
                .omitJsonWrapper(true)
                .contentOnly(update) //true for updates
                .expandSelectTree(expandSelectTreeNodeBuilder.build()) //tree of customExpanedLinks so navigation properties are serialized
                .callbacks(createCallbacks(navigationPropertyMap, rootEntityType)) // tree of callbacks to provide data for all customExpanedLinks defined above
                .build()
{code}
How can we perform such deep insert using Olingo?
 Are we using the library as intended?
 Does Olingo V2 even supports deep inserts?



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