Back to DocumentationMQL Documentation

$push

The `$push` operator is used to add a specified value to an array within a document. The $push operator adds new elements to an existing array without affecting other elements in the array.

Syntax

db.collection.update({
  <query>
}, {
  $push: {
    <field>: <value>
  }
}, {
  <options>
})

Parameters

<query>objectrequired

The selection criteria for the documents to update.

<field>stringrequired

The array field to which the value will be appended.

<value>stringrequired

The value to append to the array field.

<options>object

Optional. Additional options for the update operation.

Examples

Sample Data

{
  "_id": "0fcc0bf0-ed18-4ab8-b558-9848e18058f4",
  "name": "First Up Consultants | Beverage Shop - Satterfieldmouth",
  "sales": {
    "totalSales": 75670,
    "salesByCategory": [
      { "categoryName": "Wine Accessories", "totalSales": 34440 },
      { "categoryName": "Bitters", "totalSales": 39496 },
      { "categoryName": "Rum", "totalSales": 1734 }
    ]
  }
}

Add a new sales category

Adds a new sales category to the salesByCategory array using $push operator.

Query:

db.stores.update({
  _id: "0fcc0bf0-ed18-4ab8-b558-9848e18058f4"
}, {
  $push: {
    "sales.salesByCategory": {
      categoryName: "Wine Accessories",
      totalSales: 1000.00
    }
  }
})

Output:

[
  {
    "acknowledged": true,
    "insertedId": null,
    "matchedCount": "1",
    "modifiedCount": "1",
    "upsertedCount": 0
  }
]

Using $push with $setWindowFields

Retrieves distinct sales volumes across stores using $push in window functions.

Query:

db.stores.aggregate([
  { $match: { company: { $in: ["First Up Consultants"] } } },
  {
    $setWindowFields: {
      partitionBy: "$company",
      sortBy: { "sales.totalSales": -1 },
      output: {
        salesByStore: {
          $push: "$sales.totalSales",
          window: { documents: ["unbounded", "current"] }
        }
      }
    }
  },
  { $project: { company: 1, salesByStore: 1 } }
])

Output:

[
  {
    "_id": "a0386810-b6f8-4b05-9d60-e536fb2b0026",
    "company": "First Up Consultants",
    "salesByStore": [327583]
  },
  {
    "_id": "ad8af64a-d5bb-4162-9bb6-e5104126566d",
    "company": "First Up Consultants",
    "salesByStore": [327583, 288582]
  }
]

Related