本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。

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

Amazon DocumentDB 中的`$dayOfWeek`運算子會從指定的日期欄位中擷取一週中的某一天。它以介於 1 （週日） 和 7 （週六） 之間的數字傳回星期幾，這是與 MongoDB 中相同的行為。

**參數**
+ `date field`：要從中擷取星期幾的日期欄位。

## 範例 (MongoDB Shell)
<a name="dayOfWeek-examples"></a>

此範例示範如何使用 `$dayOfWeek` 運算子，從`weather`集合中的 `date` 欄位擷取星期幾。

**建立範例文件**

```
db.weather.insertMany([
  {
    "temperature": 97.5,
    "humidity": 0.60,
    "date": new Date("2023-04-01")
  },
  {
    "temperature": 95.2,
    "humidity": 0.55,
    "date": new Date("2023-04-02")
  },
  {
    "temperature": 92.8,
    "humidity": 0.65,
    "date": new Date("2023-04-03")
  }
]);
```

**查詢範例**

```
db.weather.aggregate([
  {
    $project: {
      dayOfWeek: { $dayOfWeek: "$date" }
    }
  }
]).pretty();
```

**輸出**

```
{ "_id" : ObjectId("64272c6663f4f8ce422c2d91"), "dayOfWeek" : 7 }
{ "_id" : ObjectId("64272c6663f4f8ce422c2d92"), "dayOfWeek" : 1 }
{ "_id" : ObjectId("64272c6663f4f8ce422c2d93"), "dayOfWeek" : 2 }
```

## 程式碼範例
<a name="dayOfWeek-code"></a>

若要檢視使用 `$dayOfWeek`命令的程式碼範例，請選擇您要使用的語言標籤：

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

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

async function main() {
  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('weather');

  const result = await collection.aggregate([
    {
      $project: {
        dayOfWeek: { $dayOfWeek: '$date' }
      }
    }
  ]).toArray();

  console.log(result);

  await client.close();
}

main();
```

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

```
from pymongo import MongoClient

def main():
    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.weather

    result = list(collection.aggregate([
        {
            '$project': {
                'dayOfWeek': { '$dayOfWeek': '$date' }
            }
        }
    ]))

    print(result)

    client.close()

if __name__ == '__main__':
    main()
```

------