Mongoose aggregate Lookup - How to filter by specific id

Question

I am trying to make a aggregate pipeline - $lookup to receive from another collection only items that are not equal to specific _id

for example :

Answer 1

You can try below aggregation for mongodb version below 3.6

db.business.aggregate([
    {$match : {_id : 1}},
    {$lookup : {from : "clinics", localField : "clinics", foreignField : "_id", as : "clinics"}},
    {$addFields : {clinics : {$filter : {input : "$clinics", as : "c", cond : {$ne : ["$$c._id", 1]}}}}}
]).pretty()

result

{ "_id" : 1, "name" : "some business name", "clinics" : [ { "_id" : 2, "name" : "some name2" }, { "_id" : 3, "name" : "some name3" } ] }