I have a query that return me something like that(I am also using Compass to see the results) :

[ { subscribers: [...] }, { subscribers: [...] }, ... ]

but what I want is to join al that “sub-arrays” called “subscribers” in one only array in an aggregation but I don’nt know how to do that. This is my code:

return this.subscriptions
        .aggregate([
            {
              '$match': {
                'entity': params.entity, 
                'status': 'active'
              }
            }, 
            {
              '$lookup': {
                'from': 'appsubscriptionssubscribers', 
                'localField': '_id', 
                'foreignField': 'subscription', 
                'as': 'subscribers'
              }
            }, 
            {
              '$match': {
                'subscribers.0': {
                  '$exists': true
                }
              }
            },
            { $skip : batch.skip },
            { $limit : batch.size },  
            {
              '$project': {
                '_id': 0, 
                'subscribers': 1
              }
            }
          ])
          .toArray();
  }

What can I do to achieve that? Thank you in advance.