Check if ID exists in a collection with mongoose - node.js

Question

For instance, I have a collection User:
var mongoose = require('mongoose');
var UserSchema = new mongoose.Schema({
email: String,
googleId: String,
facebookId: String,
displayName: String,
active: Boolean
});
module.exports = mongoose.model('User', UserSchema);
And then I have an ID:
var userID = "some-user-id"
What is the right way to just check if this id exists in the User collection. I don't need it to read the file or return it, I just need the true or false value.
Here is one way to achieve it:
User.findOne({
_id: userID
}, function (err, existingUser) {
But is there faster and more efficient way?

Answer 1

Use count rather than findOne.
This will (under the hood) cause mongoose to use find : http://docs.mongodb.org/manual/reference/method/db.collection.count
findOne() will read + return the document if it exists
On the other hand, find() just returns a cursor (or not) and only reads the data if you iterate over the cursor.
So in our case, we're not iterating over the cursor, merely counting the results returned.
User.countDocuments({_id: userID}, function (err, count){
if(count>0){
//document exists });
}
});

Answer 2

You can now use User.exists() as of September 2019 like so:
const doesUserExit = await User.exists({ _id: userID });
From the docs:
Under the hood, MyModel.exists({ answer: 42 }) is equivalent to
MyModel.findOne({ answer: 42 }).select({ _id: 1 }).lean().then(doc =>
!!doc)

Answer 3

The accepted answer is fine for small collections.
A faster way on larger collections is to simply use this:
const result = await User.findOne({ _id: userID }).select("_id").lean();
if (result) {
// user exists...
}
// or without "async/await":
User.findOne({ _id: userID }).select("_id").lean().then(result => {
if (result) {
// user exists...
}
});
It won't return all fields. I believe they are currently working on a new feature to support what you (and I) want.
In the meantime you could create a plugin, very simple and reusable.
Create an any.js file with this code:
module.exports = function any(schema, options) {
schema.statics.any = async function (query) {
const result = await this.findOne(query).select("_id").lean();
return result ? true : false;
};
}
Then in your model you do this:
var mongoose = require('mongoose');
const any = require('./plugins/any'); // I'm assuming you created a "plugins" folder for it
var UserSchema = new mongoose.Schema({
email: String,
googleId: String,
facebookId: String,
displayName: String,
active: Boolean
});
UserSchema.plugin(any);
module.exports = mongoose.model('User', UserSchema);
...and use it like this:
const result = await User.any({ _id: userID });
if (result) {
// user exists...
}
// or without using "async/await":
User.any({ _id: userID }).then(result => {
if (result) {
// user exists...
}
});

Answer 4

OR you can simply use exists function, without making any async/await:
myData = {_id: userID};
User.exists(myData,(error, result)=>{
if (error){
console.log(error)
} else {
console.log("result:", result) //result is true if myData already exists
}
});
You can play with the result now!

Answer 5

User.exists({ _id: userID }).then(exists => {
if (exists) {
res.redirect('/dashboard')
} else {
res.redirect('/login')
}
})
More info can be found at Mongoose docs.

Answer 6

The accepted answer is excellent, but I would really recommend using estimatedDocumentCount() if you are searching existing document by an indexed property (like _id of X).
On the other hand, this should actually work better and is cleaner.