public static void WriteDeltaFeed(ODataDeltaWriter deltaWriter, List<ODataItem> items, bool? countOption, Uri newDeltaLink)
{
var deltaFeed = new ODataDeltaFeed
{
DeltaLink = newDeltaLink
};
if (countOption == true)
{
deltaFeed.Count = items.Cast<object>().Count();
}
deltaWriter.WriteStart(deltaFeed);
foreach (ODataItem item in items)
{
var entry = item as ODataEntry;
var deletedEntry = item as ODataDeltaDeletedEntry;
var deltaLink = item as ODataDeltaLink;
var deltaDeletedLink = item as ODataDeltaDeletedLink;
if (entry != null)
{
deltaWriter.WriteStart(entry);
deltaWriter.WriteEnd();
}
else if (deletedEntry != null)
{
deltaWriter.WriteDeltaDeletedEntry(deletedEntry);
}
else if (deltaLink != null)
{
deltaWriter.WriteDeltaLink(deltaLink);
}
else if (deltaDeletedLink != null)
{
deltaWriter.WriteDeltaDeletedLink(deltaDeletedLink);
}
}
deltaWriter.WriteEnd();
}
private void WriteDeltaEntry(object graph, ODataDeltaWriter writer, ODataSerializerContext writeContext)
{
Contract.Assert(writeContext != null);
IEdmEntityTypeReference entityType = GetEntityType(graph, writeContext);
EntityInstanceContext entityInstanceContext = new EntityInstanceContext(writeContext, entityType, graph);
SelectExpandNode selectExpandNode = CreateSelectExpandNode(entityInstanceContext);
if (selectExpandNode != null)
{
ODataEntry entry = CreateEntry(selectExpandNode, entityInstanceContext);
if (entry != null)
{
writer.WriteStart(entry);
//TODO: Need to add support to write Navigation Links using Delta Writer
//https://github.com/OData/odata.net/issues/155
writer.WriteEnd();
}
}
}
private void WriteFeed(IEnumerable enumerable, IEdmTypeReference feedType, ODataDeltaWriter writer,
ODataSerializerContext writeContext)
{
Contract.Assert(writer != null);
Contract.Assert(writeContext != null);
Contract.Assert(enumerable != null);
Contract.Assert(feedType != null);
ODataDeltaFeed deltaFeed = CreateODataDeltaFeed(enumerable, feedType.AsCollection(), writeContext);
if (deltaFeed == null)
{
throw new SerializationException(Error.Format(SRResources.CannotSerializerNull, DeltaFeed));
}
// save this for later to support JSON odata.streaming.
Uri nextPageLink = deltaFeed.NextPageLink;
deltaFeed.NextPageLink = null;
//Start writing of the Delta Feed
writer.WriteStart(deltaFeed);
//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);
}
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:
WriteDeltaDeletedEntry(entry, writer, writeContext);
break;
case EdmDeltaEntityKind.DeletedLinkEntry:
WriteDeltaDeletedLink(entry, writer, writeContext);
break;
case EdmDeltaEntityKind.LinkEntry:
WriteDeltaLink(entry, writer, writeContext);
break;
case EdmDeltaEntityKind.Entry:
{
IEdmEntityTypeReference elementType = GetEntityType(feedType);
ODataEntityTypeSerializer entrySerializer = SerializerProvider.GetEdmTypeSerializer(elementType) as ODataEntityTypeSerializer;
if (entrySerializer == null)
{
throw new SerializationException(
Error.Format(SRResources.TypeCannotBeSerialized, elementType.FullName(), typeof(ODataMediaTypeFormatter).Name));
}
entrySerializer.WriteDeltaObjectInline(entry, elementType, writer, writeContext);
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.
if (nextPageLink != null)
{
deltaFeed.NextPageLink = nextPageLink;
}
//End Writing of the Delta Feed
writer.WriteEnd();
}
