从项目数组设置增量值

Question

如何更新MongoDB中的多个文档并按递增顺序设置元素的值？

我得到了如下文件

{
"_id" :  ObjectId("5b162a31dfaf342dc44c920d")   
}
{
"_id" :  ObjectId("5b162a31dfaf342dc44c920f")  
}
{
"_id" :  ObjectId("5b162a31dfaf342dc44c920c")  
}

如何使用单个查询更新整个文档，以便我可以在每个字段中按递增顺序添加一个名为"order"的新元素，如下所示

{
"_id" :  ObjectId("5b162a31dfaf342dc44c920d"),
"order": 1
}
{
"_id" :  ObjectId("5b162a31dfaf342dc44c920f"),
"order": 2  
}
{
"_id" :  ObjectId("5b162a31dfaf342dc44c920c"),
"order": 3  
}

目前我正在使用以下方法来解决问题

for(let i = 0; i <= req.body.id.length;i++) {
const queryOpts = {
_id: ObjectId(req.body.id[i])
};
const updateOpts = {
$set: {
'order': i + 1
}
};
const dataRes = await req.db.collection('GalleryImage').updateOne(queryOpts, updateOpts); 
if(i === req.body.id.length-1) {
return commonHelper.sendResponseMessage(res, dataRes, {
_id: req.body.id
}, moduleConfig.message.updateGalleryOrder);

}

如果有比这更好的方法，以便在有大量文档时不会是昂贵的操作？

Answer 1

将bulkWrite()与Array.map()一起使用来构造语句：

try {
let response = await req.db.collection('GalleryImage').bulkWrite(
req.body.id.map((_id,order) => 
({ updateOne: {
filter: { _id: ObjectId(_id) },
update: {
$set: { order: order+1 }
}
}})
)
);
} catch(e) {
// deal with any errors
}

Array.map()在其第二个函数参数中具有正在处理的数组元素的"索引"。因此，只需使用它来获取order并在所有语句上设置它。

这不需要n次地编写/响应数据库，而只需要"一次">发生。

除了自己介绍之外，没有其他方法可以获取"序列"，但至少我们可以用"一个">写这种方式而不是几个来做到这一点。另请注意，使用语法时要"捕获可能的错误async/await"。

---

示例列表

const { MongoClient, ObjectID: ObjectId } = require('mongodb');
const uri = 'mongodb://localhost:27017';
const data = [
"5b162a31dfaf342dc44c920d",
"5b162a31dfaf342dc44c920f",
"5b162a31dfaf342dc44c920c"
];
const log = data => console.log(JSON.stringify(data, undefined, 2));
(async function() {
try {
const client = await MongoClient.connect(uri);
let db = client.db('test');
// Set up
await db.collection('gallery').removeMany({});
await db.collection('gallery').insertMany(
data.map(_id => ({ _id: ObjectId(_id) }))
);
// Update with indexes
let response = await db.collection('gallery').bulkWrite(
data.map((_id,idx) =>
({
updateOne: {
filter: { _id: ObjectId(_id) },
update: { $set: { order: idx+1 } }
}
})
)
);
log({ response });
let items = await db.collection('gallery').find().toArray();
log({ items });
client.close();
} catch(e) {
console.error(e)
} finally {
process.exit()
}
})()

和输出

{
"response": {
"ok": 1,
"writeErrors": [],
"writeConcernErrors": [],
"insertedIds": [],
"nInserted": 0,
"nUpserted": 0,
"nMatched": 3,
"nModified": 3,
"nRemoved": 0,
"upserted": [],
"lastOp": {
"ts": "6563535160225038345",
"t": 18
}
}
}
{
"items": [
{
"_id": "5b162a31dfaf342dc44c920d",
"order": 1
},
{
"_id": "5b162a31dfaf342dc44c920f",
"order": 2
},
{
"_id": "5b162a31dfaf342dc44c920c",
"order": 3
}
]
}

清楚地显示nMatched: 3和nModified: 3正如预期的那样。