skip to Main Content

I am working on an app that uses MongoDB (I use Mongoose) as its database.

I have a question, suppose I have this kind of schema:

[{
  "user_id":"2328292073"
  "username":"Bob",
  "subscriptions":[
    {
      "id":"38271281,
      "payments":[
        {
          "id":"00001",
          "amount":"1900"
        },
         {
          "id":"00002",
          "amount":"2000"
        },
         {
          "id":"00003",
          "amount":"3000"
        }
      ]
    }
  ]

}]

In my case I want to get the payments array for subscription with id = ‘38271281’ of user with id ‘2328292073’, but I just want to retrieve the payment array, nothing else

My query is the following:

Mongoose.findOne({
  "user_id": "2328292073",
  "subscriptions.id": "38271281"
},
{
  "subscriptions.payments": 1
})

But I get the entire document of subscriptions. How can i get the payment array only?

2

Answers


  1. you can try using unwind if you want filteration from db only.

    
    Mongoose.aggregate([
      {
        '$match': {
          'user_id': '2328292093'
        }
      }, {
        '$unwind': {
          'path': '$subscriptions'
        }
      }, {
        '$match': {
          'subscriptions.id': '38271281'
        }
      }
    ])
    

    if you will have multiple documents having same subscription id then you have to group it .

    • using code level filter function can also be one another approach to do this .
    Login or Signup to reply.
  2. You can try aggregation operators in projection in find method or also use aggregation method,

    • $reduce to iterate loop of subscriptions and check the condition if id matched then return payment array
    db.collection.find({
      "user_id": "2328292073",
      "subscriptions.id": "38271281"
    },
    {
      payments: {
        $reduce: {
          input: "$subscriptions",
          initialValue: [],
          in: {
            $cond: [
              { $eq: ["$$this.id", "38271281"] },
              "$$this.payments",
              "$$value"
            ]
          }
        }
      }
    })
    

    Playground

    Login or Signup to reply.
Please signup or login to give your own answer.
Back To Top
Search