Push array to array mongodb

The following example appends 89 to the scores array:

db.students.updateOne(
   { _id: 1 },
   { $push: { scores: 89 } }
)

Example output:

{ _id: 1, scores: [ 44, 78, 38, 80, 89 ] }

Add the following documents to the students collection:

db.students.insertMany( [
   { _id: 2, scores: [ 45, 78, 38, 80, 89 ] } ,
   { _id: 3, scores: [ 46, 78, 38, 80, 89 ] } ,
   { _id: 4, scores: [ 47, 78, 38, 80, 89 ] }
] )

The following $push operation appends 95 to the scores array in each document:

db.students.updateMany(
   { },
   { $push: { scores: 95 } }
)

To confirm that each scores array includes 95, run the following operation:

The operation returns the following results:

[
   { _id: 1, scores: [ 44, 78, 38, 80, 89, 95 ] },
   { _id: 2, scores: [ 45, 78, 38, 80, 89, 95 ] },
   { _id: 3, scores: [ 46, 78, 38, 80, 89, 95 ] },
   { _id: 4, scores: [ 47, 78, 38, 80, 89, 95 ] }
]

Use $push with the $each modifier to append multiple values to the array field.

The following example appends each element of [ 90, 92, 85 ] to the scores array for the document where the name field equals joe:

db.students.updateOne(
   { name: "joe" },
   { $push: { scores: { $each: [ 90, 92, 85 ] } } }
)

Add the following document to the students collection:

db.students.insertOne(
   {
      "_id" : 5,
      "quizzes" : [
         { "wk": 1, "score" : 10 },
         { "wk": 2, "score" : 8 },
         { "wk": 3, "score" : 5 },
         { "wk": 4, "score" : 6 }
      ]
   }
)

The following $push operation uses:

• the $each modifier to add multiple documents to the quizzes array,

• the $sort modifier to sort all the elements of the modified quizzes array by the score field in descending order, and

• the $slice modifier to keep only the first three sorted elements of the quizzes array.

db.students.updateOne(
   { _id: 5 },
   {
     $push: {
       quizzes: {
          $each: [ { wk: 5, score: 8 }, { wk: 6, score: 7 }, { wk: 7, score: 6 } ],
          $sort: { score: -1 },
          $slice: 3
       }
     }
   }
)

After the operation only the three highest scoring quizzes are in the array:

{
  "_id" : 5,
  "quizzes" : [
     { "wk" : 1, "score" : 10 },
     { "wk" : 2, "score" : 8 },
     { "wk" : 5, "score" : 8 }
  ]
}

Tip