本文為英文版的機器翻譯版本，如內容有任何歧義或不一致之處，概以英文版為準。
$push
$push 彙總運算子會從每個群組的指定表達式傳回所有值的陣列。它通常在$group階段內用來將值累積到陣列中。
參數
範例 (MongoDB Shell)
下列範例示範如何使用 $push運算子來收集每個類別的所有產品名稱。
建立範例文件
db.sales.insertMany([
{ _id: 1, category: "Electronics", product: "Laptop", amount: 1200 },
{ _id: 2, category: "Electronics", product: "Mouse", amount: 25 },
{ _id: 3, category: "Furniture", product: "Desk", amount: 350 },
{ _id: 4, category: "Furniture", product: "Chair", amount: 150 },
{ _id: 5, category: "Electronics", product: "Keyboard", amount: 75 }
]);
查詢範例
db.sales.aggregate([
{
$group: {
_id: "$category",
products: { $push: "$product" }
}
}
]);
輸出
[
{ _id: 'Furniture', products: [ 'Desk', 'Chair' ] },
{ _id: 'Electronics', products: [ 'Laptop', 'Mouse', 'Keyboard' ] }
]
程式碼範例
若要檢視使用$push彙總運算子的程式碼範例，請選擇您要使用的語言標籤：
- Node.js
-
const { MongoClient } = require('mongodb');
async function 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('sales');
const result = await collection.aggregate([
{
$group: {
_id: "$category",
products: { $push: "$product" }
}
}
]).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['sales']
result = list(collection.aggregate([
{
'$group': {
'_id': '$category',
'products': { '$push': '$product' }
}
}
]))
print(result)
client.close()
example()
