MongoDB via Mongoose JS - What is findByID?

Question

I am writing a NodeJS server with ExpressJS, PassportJS, MongoDB and MongooseJS. I just managed to get PassportJS to use user data obtained via Mongoose to authenticate.

But to make it work, I had to use a "findById" function like below.

var UserModel = db.model('User',UserSchema);  UserModel.findById(id, function (err, user) { < SOME CODE > } ); 

UserModel is a Mongoose model. I declare the schema, UserSchema earlier. So I suppose UserModel.findById() is a method of the Mongoose model?

Question

What does findById do and is there documentation on it? I googled around a bit but didn't find anything.

Answer 1

findById is a convenience method on the model that's provided by Mongoose to find a document by its _id. The documentation for it can be found here.

Example:

// Search by ObjectId var id = "56e6dd2eb4494ed008d595bd"; UserModel.findById(id, function (err, user) { ... } ); 

Functionally, it's the same as calling:

UserModel.findOne({_id: id}, function (err, user) { ... }); 

Note that Mongoose will cast the provided id value to the type of _id as defined in the schema (defaulting to ObjectId).

Answer 2

If the schema of id is not of type ObjectId you cannot operate with function : findbyId()