private void TranslateSelectMany(SelectManyExpression node)
{
Translate(node.Source);
var isLeftOuterJoin = false;
IFieldExpression field;
var collectionSelector = node.CollectionSelector as PipelineExpression;
if (collectionSelector != null)
{
var defaultIfEmpty = collectionSelector.Source as DefaultIfEmptyExpression;
if (defaultIfEmpty != null)
{
isLeftOuterJoin = true;
field = defaultIfEmpty.Source as IFieldExpression;
}
else
{
field = collectionSelector.Source as IFieldExpression;
}
}
else
{
field = node.CollectionSelector as IFieldExpression;
}
if (field == null)
{
var message = string.Format("The collection selector must be a field: {0}", node.ToString());
throw new NotSupportedException(message);
}
BsonValue unwindValue = "$" + field.FieldName;
var groupJoin = node.Source as GroupJoinExpression;
if (groupJoin != null && isLeftOuterJoin)
{
unwindValue = new BsonDocument
{
{ "path", unwindValue },
{ "preserveNullAndEmptyArrays", true }
};
}
_stages.Add(new BsonDocument("$unwind", unwindValue));
var projectValue = TranslateProjectValue(node.ResultSelector);
_stages.Add(new BsonDocument("$project", projectValue));
}
private void VisitSelectMany(SelectManyExpression node)
{
Visit(node.Source);
var field = node.CollectionSelector as ISerializationExpression;
if (field == null || field.SerializationInfo.ElementName == null)
{
var message = string.Format("The collection selector must be an ISerializationExpression: {0}", node.ToString());
throw new NotSupportedException(message);
}
_stages.Add(new BsonDocument("$unwind", "$" + field.SerializationInfo.ElementName));
var projection = AggregateProjectionTranslator.TranslateProject(node.ResultSelector);
_stages.Add(new BsonDocument("$project", projection));
}
private void TranslateSelectMany(SelectManyExpression node)
{
Translate(node.Source);
var field = node.CollectionSelector as IFieldExpression;
if (field == null)
{
var message = string.Format("The collection selector must be a field: {0}", node.ToString());
throw new NotSupportedException(message);
}
_stages.Add(new BsonDocument("$unwind", "$" + field.FieldName));
var projectValue = TranslateProjectValue(node.ResultSelector);
_stages.Add(new BsonDocument("$project", projectValue));
}
protected virtual Expression VisitSelectMany(SelectManyExpression node)
{
return base.VisitExtension(node);
}
