Set Incremental Values from Array of Items - node.js

Question

How to update the multiple documents in MongoDB and set the value of the element in an increasing order?
I have got the document as follows
{
"_id" : ObjectId("5b162a31dfaf342dc44c920d")
}
{
"_id" : ObjectId("5b162a31dfaf342dc44c920f")
}
{
"_id" : ObjectId("5b162a31dfaf342dc44c920c")
}
How can I update the whole documents with a single query so that I can have a new element called "order" in every single field in an increasing order as below
{
"_id" : ObjectId("5b162a31dfaf342dc44c920d"),
"order": 1
}
{
"_id" : ObjectId("5b162a31dfaf342dc44c920f"),
"order": 2
}
{
"_id" : ObjectId("5b162a31dfaf342dc44c920c"),
"order": 3
}
Currently I am using the following way to solve the problem
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);
}
If there any better way than this so that it would not be the expensive operation if there are large number of documents ?

Answer 1

Use bulkWrite() with Array.map() to construct the statement:
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() has the "index" of the array element being processed within it's second function argument. So simply use that to get the order and set that on all statements.
Rather than writing/responding with the database n times, this only needs happen "once".
There is no other way to get a "sequence" other than introducing it yourself, but at least we can do it with "one" write this way instead of several. Note also to "trap your possible errors" when using async/await syntax.
Example listing
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()
}
})()
And the output
{
"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
}
]
}
Clearly shows nMatched: 3 and nModified: 3 just as is expected.