exclude fields in $lookup aggregation
Solution 1:
In mongodb 3.6 you can use projection ($project) inside $lookup pipeline... Something like this
db.User.aggregate([
{ "$match": { "userID":"1" }},
{ "$lookup":{
"from": "Skill",
"pipeline": [
{ "$match": { "languageID": "hindiid", "skillID": { "$in": [ "javaid","pythonid" ] }}},
{ "$project": { "_id": 0 }}
],
"as": "skills"
}}
])