No ways to set instance annotation for top-level collection value

[xuzhg]

Short summary (3-5 sentences) describing the issue.

Assemblies affected

Which assemblies and versions are known to be affected e.g. OData .Net lib 7.x

Reproduce steps

Customer can query a collection value from service as:

~/odata/customers/1/data

The response should be able to include the instance annotations, for example:

{
     "@odata.context": ...,
     "@NS.Annotation": "x",
     "value": [1,2,3]
}

However, no matter 'ODataCollectionStart' or 'ODataCollectionValue' doesn't allow to specify the instance annotations.

Expected result

{
     "@odata.context": ...,
     "@NS.Annotation": "x",
     "value": [1,2,3]
}

Actual result

{
     "@odata.context": ...,
     "value": [1,2,3]
}

Additional detail

Optional, details of the root cause if known. Delete this section if you have no additional details to add.

[mikepizzo]

I would have expected the way to do that would be to WriteStart(ODataResourceSet), followed by WritePrimitive() for each primitive value, where the instance annotations were part of the ODataResourceSet.

[mikepizzo]

This seems to work:

                var writer = msgReader.CreateODataResourceSetWriter();
                var collection = new ODataResourceSet();
                collection.SetSerializationInfo(new ODataResourceSerializationInfo
                {
                    IsFromCollection = true,
                    ExpectedTypeName = "Edm.Int32"
                });
                collection.InstanceAnnotations.Add(new ODataInstanceAnnotation("NS.Annotation", new ODataPrimitiveValue("x")));
                writer.WriteStart(collection);
                writer.Write(new ODataPrimitiveValue(1));
                writer.Write(new ODataPrimitiveValue(2));
                writer.Write(new ODataPrimitiveValue(3));
                writer.WriteEnd();

[xuzhg]

This seems to work:

                var writer = msgReader.CreateODataResourceSetWriter();
                var collection = new ODataResourceSet();
                collection.SetSerializationInfo(new ODataResourceSerializationInfo
                {
                    IsFromCollection = true,
                    ExpectedTypeName = "Edm.Int32"
                });
                collection.InstanceAnnotations.Add(new ODataInstanceAnnotation("NS.Annotation", new ODataPrimitiveValue("x")));
                writer.WriteStart(collection);
                writer.Write(new ODataPrimitiveValue(1));
                writer.Write(new ODataPrimitiveValue(2));
                writer.Write(new ODataPrimitiveValue(3));
                writer.WriteEnd();

That's related to 'DISCUSSION'.

Shall we treat the any kind of collection of 'ODataResourceSet'?

Does it mean we don't need the 'ODataCollectionSerializer'?

So far, Web API OData use 'https://github.com/OData/AspNetCoreOData/blob/main/src/Microsoft.AspNetCore.OData/Formatter/Serialization/ODataCollectionSerializer.cs#L99' to write the top-level collection value.