Webapi: [Feature] Add Stream Support to WebApi

[liqian19891011]

Add contents for Stream support in OData V4 on odata.github.io/WebApi.

We have related questions on StackOverflow

[congysu]

Consider to support named stream (aka stream property) or media link entry (i.e., media entry)
If named stream, we need to change OData entry serializer.

``` c#
public class CustomODataEntityTypeSerializer : ODataEntityTypeSerializer
{
public CustomODataEntityTypeSerializer(IEdmEntityTypeReference entityType, ODataSerializerProvider serializerProvider)
: base(entityType, serializerProvider)
{
}

public override ODataProperty CreateStructuralProperty(IEdmStructuralProperty structuralProperty, object entityInstance, ODataSerializerContext writeContext)
{
    if (structuralProperty.Type.IsStream())
    {
        return new ODataProperty { Name = structuralProperty.Name, Value = new ODataStreamReferenceValue { ReadLink = new Uri("http://image") } };
    }

    return base.CreateStructuralProperty(structuralProperty, entityInstance, writeContext);
}

}

If media link entry, we need to create an entity type with HasStream set to true in OData v4.  E.g., use this ctor:

``` c#
public EdmEntityType(string namespaceName, string name, IEdmEntityType baseType, bool isAbstract, bool isOpen, bool hasStream);

The change is in model builder.

[sammym1982]

thanks @congysu Is this issue accepted for next release of libraries?

For interim do you have any suggestion on how we can go ahead and add the stream support.

[congysu]

@sammym1982 The related issue is https://github.com/OData/WebApi/issues/149. Can start from a blog: http://blogs.msdn.com/b/mrtechnocal/archive/2013/12/31/10462258.aspx, although it is for OData v3 Web API.

[sammym1982]

@congysu

I do tried porting that code to V4 but the issue as I mentioned in my original post on stackoverflow is there is currently no way available to mark an entity as HasStream = true. The original IEdmModel.SetHasDefaultStream seems like no longer available.

Model we have is as followos:

Entity: Incident
NavigationProperties Collection: Attachments

Therefore We want all our attachment posts to happen as below:

POST: http://foo.com/incidents(1L)/Attachments

[VikingsFan]

@sammym1982 I have a pr #379 , expose the HasStream Property, which is helpful to your customize, would you help to review?

[congysu]

We shall port the sample http://blogs.msdn.com/b/mrtechnocal/archive/2013/12/31/10462258.aspx to v4.

[raffaeu]

Guys any news on this.
We are working with OData v 4.0 and now we are completely stuck, which is very disappointing.
Can you implement in the model builder this extension and release a fixture over Nuget ASAP?

[ivanko2000]

Pinging this as 'still relevant' in case anyone is listening... :)

[lsuarez5280]

Like @ivanko2000, media resources recently became relevant to my interests/requirements as well.

[GerdN67]

We also have OData Services V4 running, and cannot integrate former streaming. Waiting for the implementation of streaming support in OData V4, please implement ASAP

[kevin-osborne]

I'm not sure if this is what they're after, but I do have streams working in my code: https://stackoverflow.com/a/48851615

[biaol-odata]

@madansr7 please prioritize.

[TehWardy]

Any intention to release this yet ?
We are in year 4 since this was raised after all.

[SiberaIndustries]

Would be very glad to hear if this issue will be fixed or not.