How to get one object from array of objects based on id in mongoose

Question

I have data like this:

{
    "global": {
        "summaryNotificationSchedule": {
            "weekDay": ["wednesday"]
        }
    },
    "userEmail": "[email protected]",
    "environments": [
        {
            "userPreference": {
                "summaryNotificationSchedule": {
                    "weekDay": ["friday"]
                }
            },
            "envId": "u1"
        },
        {
            "userPreference": {
                "summaryNotificationSchedule": {
                    "weekDay": ["tuesday"],
                }
            },
            "envId": "u2"
        }
    ]
}

and I need to get userPreference object from environments array based on envId.

Tried this but its returning complete array but I need to return object inside the array i.e. userPreference

const envData = await preferencesModel.findOne({ userEmail, "environments.envId": envId }, { 'environments.$.envId': envId }).lean();

varman · Accepted Answer · 2020-09-23 04:40:20Z

1

You can use positional operator. But be ware to use postional operator in projection

db.collection.find({
  "environments.envId": "u2"
},
{
  "environments.userPreference.$": 1
})

Working Mongo playground

Update 1,

The output is As you expected

[
  {
    $project: {
      environments: {
        $filter: {
          input: "$environments",
          cond: {
            $eq: [
              "$$this.envId",
              "u1"
            ]
          }
        }
      }
    }
  },
  {
    $project: {
      userPreference: {
        $ifNull: [
          {
            $arrayElemAt: [
              "$environments.userPreference",
              0
            ]
          },
          {}
        ]
      }
    }
  }
]

Working Mongo playground

edited Sep 23, 2020 at 4:40

answered Sep 23, 2020 at 4:25

varman

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4 Comments

kittu Over a year ago

await preferencesModel.findOne({ userEmail, "environments.envId": envId }, { "environments.userPreference.$": 1 }) it still returns the array

varman Over a year ago

u need the summaryNotificationSchedule?

kittu Over a year ago

yes but I need to return only object: { "userPreference": { "summaryNotificationSchedule": { "weekDay": ["tuesday"] } }

varman Over a year ago

Does that help you?

Dĵ ΝιΓΞΗΛψΚ · Accepted Answer · 2020-09-23 04:55:29Z

1

give the following a go:

find query:

db.collection.findOne(
    {
        userEmail: "[email protected]",
    },
    {
        environments: {
            $elemMatch: {
                envId: "u1"
            }
        }
    }
)

aggregation pipeline:

db.collection.aggregate([
    {
        $match: {
            userEmail: "[email protected]"
        }
    },
    {
        $set: {
            environments: {
                $first: {
                    $filter: {
                        input: "$environments",
                        cond: { $eq: ["$$this.envId", "u1"] }
                    }
                }

            }
        }
    },
    {
        $replaceWith: "$environments.userPreference"
    }
])

answered Sep 23, 2020 at 4:55

Dĵ ΝιΓΞΗΛψΚ

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