本文属于机器翻译版本。若本译文内容与英语原文存在差异，则一律以英文原文为准。
$setIntersection
Amazon DocumentDB 中的$setIntersection运算符用于返回两个或多个数组之间的公共元素。此运算符在处理数据集时特别有用，它允许您找到多个数据集的交集。
参数
-
array1: 第一个相交的数组。
-
array2: 第二个要相交的数组。
-
arrayN:（可选）要相交的其他数组。
示例（MongoDB 外壳）
以下示例演示如何使用$setIntersection运算符来查找两个数组之间的公共元素。
创建示例文档
db.collection.insertMany([
{ _id: 1, colors: ["red", "blue", "green"] },
{ _id: 2, colors: ["blue", "yellow", "orange"] },
{ _id: 3, colors: ["red", "green", "purple"] }
])
查询示例
db.collection.aggregate([
{ $project: {
_id: 1,
commonColors: { $setIntersection: ["$colors", ["red", "blue", "green"]] }
}
}
])
输出
[
{ "_id": 1, "commonColors": ["red", "blue", "green"] },
{ "_id": 2, "commonColors": ["blue"] },
{ "_id": 3, "commonColors": ["red", "green"] }
]
代码示例
要查看使用该$setIntersection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 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('mycollection');
const result = await collection.aggregate([
{
$project: {
_id: 1,
commonColors: { $setIntersection: ["$colors", ["red", "blue", "green"]] }
}
}
]).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['mycollection']
result = list(collection.aggregate([
{
'$project': {
'_id': 1,
'commonColors': { '$setIntersection': ["$colors", ["red", "blue", "green"]] }
}
}
]))
print(result)
client.close()
example()
