CODEWITHSUNDEEP
mongodb
Karen
Karen

Reputation: 49

mongoDB return only one field from aggregation

I have 2 collections:

Users:

"_id": {
    "$oid": "62f7gsda96211065456322a10fe"
},
"name": "test",
"roles": ["user"],
"type": "user",
"fullName": "Test Test",
"email": "[email protected]",
"password_scheme": "pbkdf2",
"iterations": 10,
"derived_key": "ef150b4daa328703e68ae57f112321580ce95aa4",
"salt": "1e22243068bbsbsdva8d6459a683e2903",
"isDiactivated": false,
"idclient": {
    "$oid": "60f7cca7321da11252a10fd"
}

Timelogs:

"_id": {
    "$oid": "60f7ccbd62110611252a130a"
},
"dtstart": {
    "$date": "2020-06-01T15:24:35.388Z"
},
"idstory": {
    "$oid": "60f7ccad62110611252a1271"
},
"idworkday": {
    "$oid": "60f7ccbd62110611252a1308"
},
"dtend": {
    "$date": "2020-06-01T15:35:36.856Z"
},
"idclient": {
    "$oid": "60f7cca7321da11252a10fd"
},
"idowner": {
    "$oid": "62f7gsda96211065456322a10fe"
}

in the query I need to get timelogs. Timelogs has an "idowner" field that refers to users. I want to get all the data from timelogs, but also get the "name" of the user from the Users collection.

It should look like this:

"_id": {
"$oid": "60f7ccbd62110611252a130a"
},
"dtstart": {
"$date": "2020-06-01T15:24:35.388Z"
},
"idstory": {
"$oid": "60f7ccad62110611252a1271"
},
"idworkday": {
"$oid": "60f7ccbd62110611252a1308"
},
"dtend": {
"$date": "2020-06-01T15:35:36.856Z"
},
"idclient": {
"$oid": "60f7cca762110611252a10fd"
},
"idowner": {
"$oid": "62f7gsda96211065456322a10fe"
},
"name": "test"

Upvotes: 0

Views: 886

Answers (2)

Rajdeep D
Rajdeep D

Reputation: 3900

You can use $lookup to join 2 collections

db.timelogs.aggregate([{ 
    $lookup: { 
                from: "user", //remote collection name
                localField: "idowner.oid", //timelogs collection field
                foreignField: "_id.oid", //remote collection mapping field
                as: "idowner" //to be imported as
              } 
  }
  ,{$unwind:"$idowner"}
,{$project:{ 
            dtstart:1,
            idstory:1,
            idworkday:1,
            dtend:1,
            idclient:1,
            idowner:"$idowner._id",
            name:"$idowner.name"
    }}
])

Upvotes: 1

Sumen Kr Mallick
Sumen Kr Mallick

Reputation: 81

db.timelogs.aggregate([{ 
    $lookup: { 
                from: "user", 
                localField: "idowner.oid", 
                foreignField: "_id.oid", 
                as: "User" 
              } 
  }
  ,{$unwind:"$User"}
  ,{$project:{
   'User':'$User.name'
])

Upvotes: 0

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