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

在 5.0 中引入

Amazon DocumentDB 中的`$replaceAll`运算符用于将字段中所有出现的指定字符串模式替换为新字符串。此运算符可用于数据标准化、文本清理和字符串操作等任务。

**参数**
+ `input`：包含要替换的字符串的字段或表达式。
+ `find`：要搜索和替换的字符串模式。
+ `replacement`: 用于替换匹配匹配项的字符串。

## 示例（MongoDB 外壳）
<a name="replaceAll-examples"></a>

以下示例演示了如何在聚合管道中使用`$replaceAll`运算符将所有出现的字符串 “Chocolatier” 替换为 “Chocolatier Co.” 在 “产品” 系列的 “品牌名称” 字段中。

**创建示例文档**

```
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
  }
]);
```

**查询示例**

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

**输出**

```
[
  {
    _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
  }
]
```

## 代码示例
<a name="replaceAll-code"></a>

要查看使用该`$replaceAll`命令的代码示例，请选择要使用的语言的选项卡：

------
#### [ 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()
```

------