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

在 5.0 中推出

Amazon DocumentDB 中的`$replaceAll`運算子用於以新字串取代欄位內所有出現的指定字串模式。此運算子對於資料正規化、文字清理和字串操作等任務非常有用。

**參數**
+ `input`：包含要取代之字串的欄位或表達式。
+ `find`：要搜尋和取代的字串模式。
+ `replacement`：用來取代相符出現次數的字串。

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

下列範例示範如何在彙總管道中使用 `$replaceAll` 運算子，將字串 "Chocolatier" 的所有出現取代為 "Chocolate Co."。在「產品」集合的「brandName」欄位中。

**建立範例文件**

```
db.products.insertMany([
  {
    "_id": 1,
    "productId": "PROD-0Y9GL0",
    "brandName": "Gordon's Chocolatier",
    "category": "CPG",
    "rating": {
      "average": 4.8
    }
  },
  {
    "_id": 2,
    "productId": "PROD-1X2YZ3",
    "brandName": "Premium Chocolatier",
    "category": "CPG",
    "rating": {
      "average": 4.5
    }
  },
  {
    "_id": 3,
    "productId": "PROD-Y2E9H5",
    "name": "Nutrition Co. - Original Corn Flakes Cereal",
    "category": "Breakfast Cereals",
    "price": 8.5
  }
]);
```

**查詢範例**

```
db.products.aggregate([
  {
    $addFields: {
      "brandName": {
        $replaceAll: {
          input: "$brandName",
          find: "Chocolatier",
          replacement: "Chocolate Co."
        }
      }
    }
  }
])
```

**輸出**

```
[
  {
    _id: 1,
    productId: 'PROD-0Y9GL0',
    brandName: "Gordon's Chocolate Co.",
    category: 'CPG',
    rating: { average: 4.8 }
  },
  {
    _id: 2,
    productId: 'PROD-1X2YZ3',
    brandName: 'Premium Chocolate Co.',
    category: 'CPG',
    rating: { average: 4.5 }
  },
  {
    _id: 3,
    productId: 'PROD-Y2E9H5',
    name: 'Nutrition Co. - Original Corn Flakes Cereal',
    category: 'Breakfast Cereals',
    price: 8.5,
    brandName: null
  }
]
```

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

若要檢視使用 `$replaceAll`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 replaceAll() {
  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('products');

  const results = await collection.aggregate([
    {
      $addFields: {
        "brandName": {
          $replaceAll: {
            input: "$brandName",
            find: "Chocolatier",
            replacement: "Chocolate Co."
          }
        }
      }
    }
  ]).toArray();

  console.log(results);

  await client.close();
}

replaceAll();
```

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

```
from pymongo import MongoClient

def replace_all():
    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.products

    results = list(collection.aggregate([
        {
            "$addFields": {
                "brandName": {
                    "$replaceAll": {
                        "input": "$brandName",
                        "find": "Chocolatier",
                        "replacement": "Chocolate Co."
                    }
                }
            }
        }
    ]))

    print(results)

    client.close()

replace_all()
```

------