[OLINGO-975] Olingo client sends incorrect types for collection members

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: (Java) V4 4.1.0
• Fix Version/s: (Java) V4 4.4.0
• Component/s: odata4-client
• Assignee: Christian Amend
• Reporter: Torsten Küpper
• Created: 23/Jun/16 10:07
• Updated: 27/Apr/17 11:12
• Resolved: 27/Apr/17 11:12

Description

Hi,

having derived class types in a collection, the Olingo Java client
sends only the collection type. E.g. given that Employee and Customer both inherit from Person, and we have a collection RelatedPersons of Person, if the first collection member is an instance of Employee and the second a Customer, then the request contains

"[e-mail]": "#Collection(Person)",
"RelatedPersons": [

{ "@odata.type": "Person", ... }

,

{ "@odata.type": "Person", ... }

]

but correct would be

"[e-mail]": "#Collection(Person)",
"RelatedPersons": [

{ "@odata.type": "Employee", ... }

,

{ "@odata.type": "Customer", ... }

]

I found OLINGO-825 which seems to describe the issue just on the server
side, which then received a fix.

It seems to me the cause is that type gets lost in ODataBinderImpl when a translation of data to some internal representation which has no type information, at least for collection members, is done.

In the reverse direction, when Olingo client receives a response, the type info is thrown away in JsonDeserializer in fromCollection

if (child.has(Constants.JSON_TYPE))

{ ((ObjectNode) child).remove(Constants.JSON_TYPE); }

What could be done to fix this?
Would a change be accepted which adds the type information to each
collection member in the internal representation?