public static RenderedProjectionDefinition <TResult> TranslateGroup <TKey, TDocument, TResult>(Expression <Func <TDocument, TKey> > idProjector, Expression <Func <IGrouping <TKey, TDocument>, TResult> > groupProjector, IBsonSerializer <TDocument> parameterSerializer, IBsonSerializerRegistry serializerRegistry)
{
var keyBinder = new SerializationInfoBinder(serializerRegistry);
var boundKeyExpression = BindSerializationInfo(keyBinder, idProjector, parameterSerializer);
if (!(boundKeyExpression is ISerializationExpression))
{
var keySerializer = SerializerBuilder.Build(boundKeyExpression, serializerRegistry);
boundKeyExpression = new SerializationExpression(
boundKeyExpression,
new BsonSerializationInfo(null, keySerializer, typeof(TKey)));
}
var idExpression = new GroupIdExpression(boundKeyExpression, ((ISerializationExpression)boundKeyExpression).SerializationInfo);
var groupBinder = new AccumulatorBinder(serializerRegistry);
groupBinder.RegisterMemberReplacement(typeof(IGrouping <TKey, TDocument>).GetProperty("Key"), idExpression);
var groupSerializer = new ArraySerializer <TDocument>(parameterSerializer);
var boundGroupExpression = BindSerializationInfo(groupBinder, groupProjector, groupSerializer);
var projectionSerializer = (IBsonSerializer <TResult>)SerializerBuilder.Build(boundGroupExpression, serializerRegistry);
var projection = AggregateLanguageTranslator.Translate(boundGroupExpression).AsBsonDocument;
// must have an "_id" in a group document
if (!projection.Contains("_id"))
{
var idProjection = AggregateLanguageTranslator.Translate(boundKeyExpression);
projection.InsertAt(0, new BsonElement("_id", idProjection));
}
return(new RenderedProjectionDefinition <TResult>(projection, projectionSerializer));
}
private SerializationExpression BuildProjector(ProjectionExpression projection, ProjectionBindingContext context, GroupIdExpression id, Expression selector)
{
BsonSerializationInfo projectorSerializationInfo;
var projectorSerializationExpression = projection.Projector as ISerializationExpression;
if (projectorSerializationExpression != null)
{
projectorSerializationInfo = projectorSerializationExpression.SerializationInfo;
}
else
{
var projectorSerializer = context.SerializerRegistry.GetSerializer(projection.Projector.Type);
projectorSerializationInfo = new BsonSerializationInfo(
null,
projectorSerializer,
projectorSerializer.ValueType);
}
var serializerType = typeof(GroupingDeserializer <,>).MakeGenericType(id.Type, projection.Projector.Type);
var serializer = (IBsonSerializer)Activator.CreateInstance(serializerType, id.SerializationInfo, projectorSerializationInfo);
var info = new BsonSerializationInfo(null, serializer, serializer.ValueType);
var projector = new SerializationExpression(selector, info);
return(projector);
}
