CODEWITHSUNDEEP
javascriptmongodbmongooseaggregation-framework
Gabriel Savian
Gabriel Savian

Reputation: 224

Match not working in MongoDB. Match is returning an empty array

I'm trying to create an aggregation pipeline. The beginning of the code works okay. But when comes to the $match, the code returns nothing. Here is my code:

    var userId = req.params.UserId
    const measure = await Measure.aggregate([
        {
            $project: {
                user: 1, creationDate: 1, WaterConsumption: 1
            }
        }, 
        {
            $match: {
                user: userId
            }
        },
        {
            $group: {
                _id: {
                    $dayOfMonth: "$creationDate"
                },
                waterConsumption: {$sum :  "$WaterConsumption"}
            }
        }
    ]);
    return res.json({measure})

My data is:

{
  "measures": [
    {
      "creationDate": "2021-03-19T10:25:05.674Z",
      "_id": "605870bffa87a605bf2a983a",
      "avgPower": 8241,
      "WaterConsumption": 22,
      "avgTemperature": 45,
      "shower": "5fb56ce7734b7e04b9c97c9b",
      "user": "5f6cb0496a8c5a0deaa1a746"
    },
    {
      "creationDate": "2021-03-19T10:25:05.674Z",
      "_id": "605870d9fa87a605bf2a983b",
      "avgPower": 8241,
      "WaterConsumption": 22,
      "avgTemperature": 45,
      "shower": "5fb56ce7734b7e04b9c97c9b",
      "user": "5f6cb0496a8c5a0deaa1a746"
    },
    {
      "creationDate": "2021-03-17T10:25:05.674Z",
      "_id": "605870ebfa87a605bf2a983c",
      "avgPower": 4300,
      "WaterConsumption": 32,
      "avgTemperature": 28,
      "shower": "5fb56d04734b7e04b9c97c9c",
      "user": "5f6cb0496a8c5a0deaa1a746",
    }...
  ]

The code runs perfect till it reaches the $match. If I console my userId it is a string with the user value "5f6cb0496a8c5a0deaa1a746". I don't know why $match is not working. The $group is working perfectly. I tried to swap the match to $match:{user: req.params.UserId} but the code keeps returning an empty array.

Upvotes: 0

Views: 224

Answers (1)

Tushar Gupta - curioustushar
Tushar Gupta - curioustushar

Reputation: 57105

You are trying to match string with ObjectID that's why your $match is not working.

ObjectId

Working demo with ObjectID - https://mongoplayground.net/p/Oz95gFwvp9X

const mongodb = require('mongodb');
const ObjectID = mongodb.ObjectID;
const userId = ObjectID(req.params.UserId); // convert your userid to ObjctedID format

Eg - userId - 5f6cb0496a8c5a0deaa1a746 will be converted to ObjectId("5f6cb0496a8c5a0deaa1a746")

Not working with string - https://mongoplayground.net/p/5PN8WeXt2zc

Upvotes: 2

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