Join return an empty array

[steevej (Steeve Juneau)]

Please provide sample documents from the source collections.

Please provide expected results.

Please provide the pipeline you have tried.

As for

@Mohamed_Habib

Another question if i could use look up on a pipeline aggregation instead a collection thank you

you may be able to create a view from the pipeline and then lookup on the view. See https://docs.mongodb.com/manual/core/views/