/// <inheritdoc />
public override async Task WriteObjectAsync(object graph, Type type, ODataMessageWriter messageWriter, ODataSerializerContext writeContext)
{
if (messageWriter == null)
{
throw Error.ArgumentNull("messageWriter");
}
if (writeContext == null)
{
throw Error.ArgumentNull("writeContext");
}
if (graph == null)
{
throw new SerializationException(Error.Format(SRResources.CannotSerializerNull, DeltaFeed));
}
IEdmEntitySetBase entitySet = writeContext.NavigationSource as IEdmEntitySetBase;
if (entitySet == null)
{
throw new SerializationException(SRResources.EntitySetMissingDuringSerialization);
}
IEdmTypeReference feedType = writeContext.GetEdmType(graph, type);
Contract.Assert(feedType != null);
IEdmEntityTypeReference entityType = GetEntityType(feedType);
ODataDeltaWriter writer = messageWriter.CreateODataDeltaWriter(entitySet, entityType.EntityDefinition());
await WriteDeltaFeedInline(graph, feedType, writer, writeContext);
writer.Flush();
}
public override void Process(IODataRequestMessage requestMessage, IODataResponseMessage responseMessage)
{
// TODO: we will need to add server-driven paging for delta link
object queryResults = this.QueryContext.ResolveQuery(this.DataSource);
using (var messageWriter = this.CreateMessageWriter(responseMessage))
{
IEdmNavigationSource navigationSource = this.QueryContext.Target.NavigationSource;
IEnumerable iEnumerableResults = queryResults as IEnumerable;
if (this.QueryContext.Target.NavigationSource != null && this.QueryContext.Target.TypeKind == EdmTypeKind.Collection)
{
IEdmEntitySetBase entitySet = navigationSource as IEdmEntitySetBase;
IEdmEntityType entityType = this.QueryContext.Target.ElementType as IEdmEntityType;
if (entitySet == null || entityType == null)
{
throw new InvalidOperationException("Invalid target when query feed.");
}
GenerateDeltaItemsFromFeed(iEnumerableResults, entitySet, ODataVersion.V4, this.QueryContext.QuerySelectExpandClause);
Uri newDeltaLink = null;
if (this.PreferenceContext.TrackingChanges)
{
var newDeltaToken = DeltaContext.GenerateDeltaToken(this.QueryContext.QueryUri, iEnumerableResults, entitySet, this.QueryContext.QuerySelectExpandClause);
newDeltaLink = new Uri(string.Format("{0}?{1}={2}", this.ServiceRootUri, ServiceConstants.QueryOption_Delta, newDeltaToken));
responseMessage.AddPreferenceApplied(ServiceConstants.Preference_TrackChanging);
}
ODataDeltaWriter resultWriter = messageWriter.CreateODataDeltaWriter(entitySet, entityType);
ResponseWriter.WriteDeltaFeed(resultWriter, this.DeltaItems, this.QueryContext.CountOption, newDeltaLink);
resultWriter.Flush();
}
else
{
throw Utility.BuildException(HttpStatusCode.Gone);
}
}
}