Project and filter double nested array mongodb

Question

{
   "id":"",
   "data0":"",
   "data1":[
      {
         "data2":[
            {
               "name":"Man 1",
               "_id":"5e8c242f751d0074ca004a"
            },
            {
               "name":"Man 2",
               "_id":"605d403dab6100e1395697"
            },
            {
               "name":"Man 3",
               "_id":"5e8c2d39751d0074ca0050"
            }
         ]
      },
      {
         "data2":[
            {
               "name":"Man 4",
               "_id":"5ed4efc71224005abea7eb"
            },
            {
               "name":"Man 5",
               "_id":"5e8c249539751d04ca0056"
            },
            {
               "name":"Man 6",
               "_id":"5e8c239a39751d0074c046"
            }
         ]
      }
   ]
}

The document above is the structure of my data. Is there a way i can filter the element of an array (data1) where name is Man 3. I want to show only the array element where the value of name is Man 3. I have this code but it is not working. heres the sample.

                    pipeLine.push(
                    { $project: { 
                        'data1' : {
                            $filter: {
                                input: '$data1.data2',
                                as: 'test',
                                cond: { $eq : ['$$test.name', "Man 3" ]}
                            }
                        }
                     }}
                )

Expected output is this.

{
   "id":"",
   "data0":"",
   "data1":[
      {
         "data2":[
            {
               "name":"Man 1",
               "_id":"5e8c242f751d0074ca004a"
            },
            {
               "name":"Man 2",
               "_id":"605d403dab6100e1395697"
            },
            {
               "name":"Man 3",
               "_id":"5e8c2d39751d0074ca0050"
            }
         ]
      }
   ]
}

Yong Shun · Accepted Answer · 2022-01-24 08:43:08Z

2

You should use $in operator to check whether "Man 3" is in data1.data2.name, which this path will return the name array.

db.collection.aggregate([
  {
    $project: {
      "data1": {
        $filter: {
          input: "$data1",
          cond: {
            $in: [
              "Man 3",
              "$$this.data2.name"
            ]
          }
        }
      }
    }
  }
])

Sample Mongo Playground

answered Jan 24, 2022 at 8:43

Yong Shun

54.5k6 gold badges38 silver badges66 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

J.F. · Accepted Answer · 2022-01-24 08:44:19Z

2

If you only want that filter you can use a find query instead of an aggregation:

db.collection.find({
  "data1.data2.name": "Man 3"
},
{
  "id": 1,
  "data0": 1,
  "data1.data2.$": 1
})

Example here

Also if you want an aggregation stage use $in instead of $eq:

db.collection.aggregate([
  {
    "$project": {
      "id": 1,
      "data0": 1,
      "data1": {
        "$filter": {
          "input": "$data1",
          "as": "d",
          "cond": {
            "$in": [
              "Man 3",
              "$$d.data2.name"
            ]
          }
        }
      }
    }
  }
])

Example here

answered Jan 24, 2022 at 8:44

J.F.

15.3k10 gold badges41 silver badges74 bronze badges

Collectives™ on Stack Overflow

Project and filter double nested array mongodb

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related