private async Task WriteFeedAsync(IEnumerable enumerable, IEdmTypeReference feedType, ODataWriter writer,
ODataSerializerContext writeContext)
{
Contract.Assert(writer != null);
Contract.Assert(writeContext != null);
Contract.Assert(enumerable != null);
Contract.Assert(feedType != null);
IEdmStructuredTypeReference elementType = GetResourceType(feedType);
if (elementType.IsComplex())
{
ODataResourceSet resourceSet = new ODataResourceSet()
{
TypeName = feedType.FullName()
};
await writer.WriteStartAsync(resourceSet).ConfigureAwait(false);
ODataResourceSerializer entrySerializer = SerializerProvider.GetEdmTypeSerializer(elementType) as ODataResourceSerializer;
if (entrySerializer == null)
{
throw new SerializationException(
Error.Format(SRResources.TypeCannotBeSerialized, elementType.FullName()));
}
foreach (object entry in enumerable)
{
await entrySerializer.WriteDeltaObjectInlineAsync(entry, elementType, writer, writeContext).ConfigureAwait(false);
}
}
else
{
ODataDeltaResourceSet deltaFeed = CreateODataDeltaFeed(enumerable, feedType.AsCollection(), writeContext);
if (deltaFeed == null)
{
throw new SerializationException(Error.Format(SRResources.CannotSerializerNull, DeltaFeed));
}
// save the next page link for later to support JSON odata.streaming.
Func <object, Uri> nextLinkGenerator = GetNextLinkGenerator(deltaFeed, enumerable, writeContext);
deltaFeed.NextPageLink = null;
//Start writing of the Delta Feed
await writer.WriteStartAsync(deltaFeed).ConfigureAwait(false);
object lastResource = null;
//Iterate over all the entries present and select the appropriate write method.
//Write method creates ODataDeltaDeletedEntry / ODataDeltaDeletedLink / ODataDeltaLink or ODataEntry.
foreach (object entry in enumerable)
{
if (entry == null)
{
throw new SerializationException(SRResources.NullElementInCollection);
}
lastResource = entry;
IEdmChangedObject edmChangedObject = entry as IEdmChangedObject;
if (edmChangedObject == null)
{
throw new SerializationException(Error.Format(
SRResources.CannotWriteType, GetType().Name, enumerable.GetType().FullName));
}
switch (edmChangedObject.DeltaKind)
{
case EdmDeltaEntityKind.DeletedEntry:
await WriteDeltaDeletedEntryAsync(entry, writer, writeContext).ConfigureAwait(false);
break;
case EdmDeltaEntityKind.DeletedLinkEntry:
await WriteDeltaDeletedLinkAsync(entry, writer, writeContext).ConfigureAwait(false);
break;
case EdmDeltaEntityKind.LinkEntry:
await WriteDeltaLinkAsync(entry, writer, writeContext).ConfigureAwait(false);
break;
case EdmDeltaEntityKind.Entry:
{
ODataResourceSerializer entrySerializer = SerializerProvider.GetEdmTypeSerializer(elementType) as ODataResourceSerializer;
if (entrySerializer == null)
{
throw new SerializationException(
Error.Format(SRResources.TypeCannotBeSerialized, elementType.FullName()));
}
await entrySerializer.WriteDeltaObjectInlineAsync(entry, elementType, writer, writeContext)
.ConfigureAwait(false);
break;
}
default:
break;
}
}
// Subtle and surprising behavior: If the NextPageLink property is set before calling WriteStart(feed),
// the next page link will be written early in a manner not compatible with odata.streaming=true. Instead, if
// the next page link is not set when calling WriteStart(feed) but is instead set later on that feed
// object before calling WriteEnd(), the next page link will be written at the end, as required for
// odata.streaming=true support.
deltaFeed.NextPageLink = nextLinkGenerator(lastResource);
}
//End Writing of the Delta Feed
await writer.WriteEndAsync().ConfigureAwait(false);
}
