mongodb update and push array of objects

Question

I have this simple collection of students:

{
    "_id": "btv7865reVGlksabv",
    "students": [
        {
            "name": "John",
            "age": 30
        },
        {
            "name": "Henry",
            "age": 25
        }
    ]
}

Now I want to push new students into this array:

const newStudents = [
    {
        "name": "Mike",
        "age": 22
    },
    {
        "name": "Kim",
        "age": 20
    }
]

What I tried so far is:

Students.update(
    {
        "_id": "btv7865reVGlksabv"
    },
    {
        $push: {
            "students": newStudents
        }
    }
);

The above query doesn't update my collection for some reason. Can anyone help me correct this query?

ray · Accepted Answer · 2023-02-12 13:49:09Z

2

Chain up $push with $each

db.collection.update({
  "_id": "btv7865reVGlksabv"
},
{
  $push: {
    "students": {
      $each: [
        {
          "name": "Mike",
          "age": 22
        },
        {
          "name": "Kim",
          "age": 20
        }
      ]
    }
  }
})

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answered Feb 12, 2023 at 13:49

ray

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Comments

R2D2 · Accepted Answer · 2023-02-12 13:44:39Z

0

Maybe something like this:

db.collection.update({},
[
 {
  $addFields: {
  students: {
    $concatArrays: [
      "$students",
      [
        {
          name: "New1",
          age: "New1"
        },
        {
          name: "New2",
          age: "New2"
        }
      ]
    ]
  }
}
}
])

Explained:

Use $addFileds->$concatArrays to update via aggregation pipeline ( 4.2+) to add the elements from your new array to the already existing array ...

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answered Feb 12, 2023 at 13:44

R2D2

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