# \$1isoWeek
<a name="isoWeek"></a>

The `$isoWeek` operator in Amazon DocumentDB returns the ISO week number for a date. The ISO week date system is a way of numbering weeks in a year, in which the first week of a new year is the week that contains the first Thursday of that year. This is different from the Gregorian calendar, where the first week of a new year is the week that contains January 1.

**Parameters**

None

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

The following example demonstrates how to use the `$isoWeek` operator to retrieve the ISO week number for a given date.

**Create sample documents**

```
db.dates.insertMany([
  { _id: 1, date: new ISODate("2022-01-01") },
  { _id: 2, date: new ISODate("2022-12-31") },
  { _id: 3, date: new ISODate("2023-01-01") }
])
```

**Query example**

```
db.dates.aggregate([
  {
    $project: {
      _id: 1,
      isoWeek: { $isoWeek: "$date" }
    }
  }
])
```

**Output**

```
[
  { "_id": 1, "isoWeek": 52 },
  { "_id": 2, "isoWeek": 52 },
  { "_id": 3, "isoWeek": 1 }
]
```

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

To view a code example for using the `$isoWeek` command, 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('dates');

  const result = await collection.aggregate([
    {
      $project: {
        _id: 1,
        isoWeek: { $isoWeek: "$date" }
      }
    }
  ]).toArray();

  console.log(result);
  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['dates']

    result = list(collection.aggregate([
        {
            '$project': {
                '_id': 1,
                'isoWeek': { '$isoWeek': '$date' }
            }
        }
    ]))

    print(result)
    client.close()

example()
```

------