Get all record from collection , if matches at least one record in second collection on MongoDB

[steevej (Steeve Juneau)]

@Digvijaya_Singh

f I apply the filter by region_id 7777 then I want below output. If I apply the region id 7777 and 8888

Can you clarify the above? You so not have any field named region_id so it is not clear how you would filter by region_id:7777. The values 7777 and 8888 seems to be associated with a field named location_id. So I feel you sample documents are redacted from real documents.

Despite some information that is not clear what I think could work is

• Replace the $addFields at the top level by an inner pipeline in the $lookup that $match on location_id.

The updated $lookup would look like:

```
{
   "$lookup": {
      "from": "region",
      "localField": "_id",
      "foreignField": "user_id",
      "as": "regions",
      "pipeline" : [
           { "$match" : { "location_id" : "7777" } }
      ]
    }
  }
```