protected internal virtual Expression VisitGroupJoin(GroupJoinExpression node)
{
return(node.Update(
Visit(node.Source),
Visit(node.Joined),
Visit(node.SourceKeySelector),
Visit(node.JoinedKeySelector)));
}
private void TranslateGroupJoin(GroupJoinExpression node)
{
Translate(node.Source);
var joined = node.Joined as CollectionExpression;
if (joined == null)
{
throw new NotSupportedException("Only a collection is allowed to be joined.");
}
var localFieldValue = AggregateLanguageTranslator.Translate(node.SourceKeySelector);
if (localFieldValue.BsonType != BsonType.String)
{
throw new NotSupportedException("Could not translate the local field.");
}
var localField = localFieldValue.ToString().Substring(1); // remove '$'
var foreignFieldValue = AggregateLanguageTranslator.Translate(node.JoinedKeySelector);
if (foreignFieldValue.BsonType != BsonType.String)
{
throw new NotSupportedException("Could not translate the foreign field.");
}
var foreignField = foreignFieldValue.ToString().Substring(1); // remove '$'
_stages.Add(new BsonDocument("$lookup", new BsonDocument
{
{ "from", ((CollectionExpression)node.Joined).CollectionNamespace.CollectionName },
{ "localField", localField },
{ "foreignField", foreignField },
{ "as", node.JoinedItemName }
}));
}
protected internal virtual Expression VisitGroupJoin(GroupJoinExpression node)
{
return node.Update(
Visit(node.Source),
Visit(node.Joined),
Visit(node.SourceKeySelector),
Visit(node.JoinedKeySelector));
}