Excluding an array element has a specific value

Question

I've a schema which has an array inside and I want to select an item but exclude some of the array elements which have a specific value.

Sample data:

{
  _id: 1,
  name: something,
  department: management,
  employees: [
    0: { 
      _id: 1,
      name: joe,
      suspended: false
    },
    1: {
      _id: 2,
      name: clare,
      suspended: false
    },
    2: {
      _id: 3,
      name: michelle,
      suspended: true
    }

  ]
}

I need to exclude clare and joe and all the others has suspended:false from the result. (I need to get the department and it's suspended employees inside)

Here is the code I tried but it didn't work... This code is excluding "suspended" field only. Not the array elements.

Department.findOne(
    { name:req.params.department},
    { 'employees.suspended': false }
    , function(err, result){
        if(err) {
            console.log("ERROR");
            console.log(err);
        } else {
            console.log("RESULT");
            console.log(result);
        }
    })

Valijon · Accepted Answer · 2020-03-04 09:40:20Z

1

You can do it with MongoDB Aggregation framework

Department.aggregate([
  {
    $match: {
      name: req.params.department
    }
  },
  {
    $addFields: {
      employees: {
        $filter: {
          input: "$employees",
          cond: {
            $ne: [
              "$$this.suspended",
              false
            ]
          }
        }
      }
    }
  }
]).exec(err, result){
    if(err) {
        console.log("ERROR");
        console.log(err);
    } else {
        console.log("RESULT");
        console.log(result);
    }
})

MongoPlayground

edited Mar 4, 2020 at 9:40

answered Mar 4, 2020 at 8:28

Valijon

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7 Comments

Utku Demir Over a year ago

Working correctly on MongoPlayground but it returns an empty array on mongoose.

Valijon Over a year ago

@UtkuDemir make sure req.params.department has valid string value

Utku Demir Over a year ago

It's my bad. I was trying to match with _id but I didn't know I need to convert string to ObjectId first. So this is working code for $match now: $match: { "_id": mongoose.Types.ObjectId(req.params.id) }

Valijon Over a year ago

@UtkuDemir excellent. You add more pipeline to aggregation to filter and transform your data

Utku Demir Over a year ago

thanks a lot. I've got one last question... Let's say I want to exclude employees names from the result to reduce response size... What should I do?

|

Wernfried Domscheit · Accepted Answer · 2020-03-04 09:30:54Z

0

Try this one:

db.collection.aggregate([
   { $match: { name: req.params.department } },
   {
      $set: {
         employees: {
            $filter: {
               input: "$employees",
               cond: "$$this.suspended"
            }
         }
      }
   }
])

Mongo playground

edited Mar 4, 2020 at 9:30

answered Mar 4, 2020 at 8:28

Wernfried Domscheit

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1 Comment

Utku Demir Over a year ago

It's filtering employees correctly but there're lots of departments and I need to select just one by name. I tried to use "$match" but returned an empty array.

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