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

Amazon DocumentDB 中的`$nearSphere`运算符用于查找距离地理空间点指定距离内的文档。此运算符对于地理空间查询特别有用，例如查找给定位置一定半径范围内的所有餐厅。

**参数**
+ `$geometry`: 表示参考点的 GeoJSON 对象。必须是带有`type`和`coordinates`字段的`Point`对象。
+ `$minDistance`:（可选）文档必须位于的参考点的最小距离（以米为单位）。
+ `$maxDistance`:（可选）从文档必须位于的参考点的最大距离（以米为单位）。

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

在此示例中，我们将找到距离华盛顿州西雅图特定地点 2 千米（2000 米）范围内的所有餐厅。

**创建示例文档**

```
db.usarestaurants.insert([
  {
    name: "Noodle House",
    location: { type: "Point", coordinates: [-122.3516, 47.6156] }
  },
  {
    name: "Pike Place Grill",
    location: { type: "Point", coordinates: [-122.3403, 47.6101] }
  },
  {
    name: "Seattle Coffee Co.",
    location: { type: "Point", coordinates: [-122.3339, 47.6062] }
  }
]);
```

**查询示例**

```
db.usarestaurants.find({
  location: {
    $nearSphere: {
      $geometry: {
        type: "Point",
        coordinates: [-122.3516, 47.6156]
      },
      $minDistance: 1,
      $maxDistance: 2000
    }
  }
}, {
  name: 1
});
```

**输出**

```
{ "_id" : ObjectId("611f3da985009a81ad38e74b"), "name" : "Noodle House" }
{ "_id" : ObjectId("611f3da985009a81ad38e74c"), "name" : "Pike Place Grill" }
```

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

要查看使用该`$nearSphere`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 findNearbyRestaurants() {
  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 restaurants = db.collection('usarestaurants');

  const result = await restaurants.find({
    location: {
      $nearSphere: {
        $geometry: {
          type: "Point",
          coordinates: [-122.3516, 47.6156]
        },
        $minDistance: 1,
        $maxDistance: 2000
      }
    }
  }, {
    projection: { name: 1 }
  }).toArray();

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

findNearbyRestaurants();
```

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

```
from pymongo import MongoClient

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

    result = list(restaurants.find({
        'location': {
            '$nearSphere': {
                '$geometry': {
                    'type': 'Point',
                    'coordinates': [-122.3516, 47.6156]
                },
                '$minDistance': 1,
                '$maxDistance': 2000
            }
        }
    }, {
        'name': 1
    }))

    print(result)
    client.close()

find_nearby_restaurants()
```

------