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$setEquals
Amazon DocumentDB 中的$setEquals运算符用于确定两组是否相等。它比较两个数组，并返回它们true是否包含相同的不同元素，无论它们的顺序如何。
参数
-
expression1: 第一个要比较的数组。
-
expression2: 第二个要比较的数组。
示例（MongoDB 外壳）
以下示例演示如何使用运$setEquals算符比较两组值。
创建示例文档
db.collection.insertMany([
{ _id: 1, fruits: ["apple", "banana", "cherry"] },
{ _id: 2, fruits: ["banana", "apple", "cherry"] },
{ _id: 3, fruits: ["apple", "banana", "orange"] }
])
查询示例
db.collection.find({
$expr: {
$setEquals: ["$fruits", ["apple", "banana", "cherry"]]
}
})
输出
{ "_id" : 1, "fruits" : [ "apple", "banana", "cherry" ] }
{ "_id" : 2, "fruits" : [ "banana", "apple", "cherry" ] }
该查询使用$setEquals运算符将每个文档的fruits字段与数组进行比较["apple", "banana", "cherry"]。返回该fruits字段等于比较数组的文档。
代码示例
要查看使用该$setEquals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');
// Insert sample documents
await collection.insertMany([
{ _id: 1, fruits: ["apple", "banana", "cherry"] },
{ _id: 2, fruits: ["banana", "apple", "cherry"] },
{ _id: 3, fruits: ["apple", "banana", "orange"] }
]);
// Query using $setEquals
const result = await collection.find({
$expr: {
$setEquals: ["$fruits", ["apple", "banana", "cherry"]]
}
}).toArray();
console.log(result);
await 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']
# Insert sample documents
collection.insert_many([
{"_id": 1, "fruits": ["apple", "banana", "cherry"]},
{"_id": 2, "fruits": ["banana", "apple", "cherry"]},
{"_id": 3, "fruits": ["apple", "banana", "orange"]}
])
# Query using $setEquals
result = list(collection.find({
"$expr": {
"$setEquals": ["$fruits", ["apple", "banana", "cherry"]]
}
}))
print(result)
client.close()
example()
