javascript - Find after populate mongoose

Question

I'm having some trouble querying a document by values matching inside the document after population by mongoose.

My schemas are something like this:

var EmailSchema = new mongoose.Schema({
  type: String
});

var UserSchema = new mongoose.Schema({
  name: String,
  email: [{type:Schema.Types.ObjectId, ref:'Email'}]
});

I would like to have all users which have a email with the type = "Gmail" for example.

The following query returns empty results:

Users.find({'email.type':'Gmail').populate('email').exec( function(err, users)
    {
      res.json(users);
    });

I have had to resort to filtering the results in JS like this:

users = users.filter(function(user)
        {
          for (var index = 0; index < user.email.length; index++) {
            var email = user.email[index];
            if(email.type === "Gmail")
            {
              return true;
            }
          }
          return false;
        });

Is there any way to query something like this straight from mongoose?

Answer 1

@Jason Cust explained it pretty well already - in this situation often the best solution is to alter the schema to prevent querying Users by properties of documents stored in separate collection.

Here's the best solution I can think of that will not force you to do that, though (because you said in the comment that you can't).

Users.find().populate({
  path: 'email',
  match: {
    type: 'Gmail'
  }
}).exec(function(err, users) {
  users = users.filter(function(user) {
    return user.email; // return only users with email matching 'type: "Gmail"' query
  });
});

What we're doing here is populating only emails matching additional query (match option in .populate() call) - otherwise email field in Users documents will be set to null.

All that's left is .filter on returned users array, like in your original question - only with much simpler, very generic check. As you can see - either the email is there or it isn't.