JIYIK CN >

This MongoDB article will discuss the use of the $in operator in MongoDB.

IN Operator ($in) in MongoDB

MongoDB comes with a number of operators for a range of tasks. The $in operator allows you to precisely locate a document, find()and update()the methods can be used with this operator.

The $in operator compares the value of a field with the values ​​provided in an array to select documents in a collection. If the value of a document field is an array, MongoDB's $in operator will select only those documents where the field contains an array and at least one item matches the provided value.

grammar:

{ field: { $in: [<value1>, <value2>, ... <valuen> ] }

Using the $in operator to match values ​​in MongoDB

Suppose you have a fruit store database management system, and you have a database where you store all the data of your fruit items, such as price, quantity, weight, etc. We will discuss below how to extract the documents that match the result based on a given value.

First, start your MongoDB server and pass the following command to list all databases and use your database.

Order:

show dbs
use data

Let's list all the documents in the collection you have. You can then use the $in operator on them to filter out based on a specific value.

db={
  "data": [
    {
      "_id": ObjectId("6034fd2bf74cfd0438bdb19b"),
      "onSale": false,
      "name": "Orange",
      "price": 500,
      "weight": "1 kilograms",
      "__v": 0
    },
    {
      "_id": ObjectId("603502ba24df1c2350e676e7"),
      "onSale": false,
      "name": "Banana",
      "price": 350,
      "weight": "2 dozen",
      "__v": 0
    },
    {
      "_id": ObjectId("603502ba24df1c2350e676e8"),
      "onSale": false,
      "name": "Apple",
      "price": 125,
      "weight": "500 grams",
      "__v": 0
    },
    {
      "_id": ObjectId("603502ba24df1c2350e676e9"),
      "onSale": false,
      "name": "Mango",
      "price": 300,
      "weight": "4 kilograms",
      "__v": 0
    }
  ]
}

Updating Documents in MongoDB Using $in Operator

Use the method on a document update()to update the value of certain documents.

db={
  "data": [
    {
      "_id": ObjectId("6034fd2bf74cfd0438bdb19b"),
      "onSale": false,
      "name": "Orange",
      "price": 500,
      "weight": "1 kilograms",
      "__v": 0
    },
    {
      "_id": ObjectId("603502ba24df1c2350e676e7"),
      "onSale": false,
      "name": "Banana",
      "price": 350,
      "weight": "2 dozen",
      "__v": 0
    },
    {
      "_id": ObjectId("603502ba24df1c2350e676e8"),
      "onSale": false,
      "name": "Apple",
      "price": 125,
      "weight": "500 grams",
      "__v": 0
    },
    {
      "_id": ObjectId("603502ba24df1c2350e676e9"),
      "onSale": false,
      "name": "Mango",
      "price": 300,
      "weight": "4 kilograms",
      "__v": 0
    }
  ]
}

If you want to change the price of the fruit "Apple". You can change the price of "Apple" to "200" through this query.

Query:

db.data.update({
  name: {
    $in: [
      "Apple"
    ]
  }
},
{
  $set: {
    price: 200
  }
})

After using find()the method, you will get the following result. update()The price of "Apple" is updated from 125 to 200 using the $in operator in the method.

Output:

Through this MongoDB tutorial article, you have learned what the $in operator is, how to use the $in operator to match values ​​in a database collection, and how to update or edit a given collection in the database.