# \$1in
<a name="in-aggregation"></a>

The `$in` aggregation operator checks if a specified value exists within an array. It returns `true` if the value is found in the array, and `false` otherwise.

**Parameters**
+ `value`: The value to search for.
+ `array`: The array to search within.

## Example (MongoDB Shell)
<a name="in-aggregation-examples"></a>

The following example demonstrates using the `$in` operator to check if a specific skill exists in each employee's skill set.

**Create sample documents**

```
db.employees.insertMany([
  { _id: 1, name: "Sarah", skills: ["Python", "JavaScript", "SQL"] },
  { _id: 2, name: "Mike", skills: ["Java", "C++", "Go"] },
  { _id: 3, name: "Emma", skills: ["Python", "Ruby", "Rust"] }
]);
```

**Query example**

```
db.employees.aggregate([
  {
    $project: {
      name: 1,
      hasPython: { $in: ["Python", "$skills"] }
    }
  }
]);
```

**Output**

```
[
  { _id: 1, name: 'Sarah', hasPython: true },
  { _id: 2, name: 'Mike', hasPython: false },
  { _id: 3, name: 'Emma', hasPython: true }
]
```

## Code examples
<a name="in-aggregation-code"></a>

To view a code example for using the `$in` aggregation operator, choose the tab for the language that you want to use:

------
#### [ Node.js ]

```
const { MongoClient } = require('mongodb');

async function example() {
  const client = await MongoClient.connect('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false');
  const db = client.db('test');
  const collection = db.collection('employees');

  const result = await collection.aggregate([
    {
      $project: {
        name: 1,
        hasPython: { $in: ["Python", "$skills"] }
      }
    }
  ]).toArray();

  console.log(result);
  await client.close();
}

example();
```

------
#### [ Python ]

```
from pymongo import MongoClient

def example():
    client = MongoClient('mongodb://<username>:<password>@<cluster-endpoint>:27017/?tls=true&tlsCAFile=global-bundle.pem&replicaSet=rs0&readPreference=secondaryPreferred&retryWrites=false')
    db = client['test']
    collection = db['employees']

    result = list(collection.aggregate([
        {
            '$project': {
                'name': 1,
                'hasPython': { '$in': ['Python', '$skills'] }
            }
        }
    ]))

    print(result)
    client.close()

example()
```

------