Find by id or username in mongo

Question

I'm trying to do a find by username or _id like this

exports.getUser = function (req, res){
    User.find({ $or: [ {username:req.params.id}, {_id:req.params.id} ] })
        .exec(function (err, collections) {
    res.send(collections);
    });
};

It works when I search by _id but fails for username because it fails to return a valid OjectID. I tried doing two separate queries like this

exports.getUser = function (req, res){
    User.findOne({username:req.params.id}).exec(function (err, user) {
        if (user)
            res.send(user);
    });

    User.findById({_id:req.params.id}).exec(function (err, user) {
        if (user)
            res.send(user);
    });
};

but this hangs if the user doesn't exist because it never sends a response. Since node is async I get Error: Can't set headers after they are sent. if I add

else
    res.sendStatus(400);

to the findById query. I can't think of any other way to solve this.I tried the regex in MongoDB Node check if objectid is valid

exports.getUser = function (req, res){
    var checkForHexRegExp = new RegExp("^[0-9a-fA-F]{24}$");
    if(checkForHexRegExp.test(req.params.id)){
        User.findById({_id:req.params.id}).exec(function (err, user) {
            if (user)
                res.send(user);
        });
    }
    User.findOne({username:req.params.id}).exec(function (err, user) {
            res.send(user);
    });

};

And I'm getting the same error because it's async. There has to be a better way than this

Why exactly does your first option not work? it should work, assuming you expected it to return an array rather than a single user. — Kevin B, Jun 04 '15 at 19:15
What do you mean by _"it fails to return a valid ObjectID"_? — robertklep, Jun 04 '15 at 19:15
@KevinB It fails because when you provide {_id:req.params.id} with a username instead of a 24 bit hexcode mongo throws an error and the query fails. So if req.params.id is "556e06662a6efc6c2544773b" it works fine, but it its "myusername" it fails — Jake, Jun 04 '15 at 20:08

score 6 · Accepted Answer · answered Jun 04 '15 at 19:22

Most likely your first query won't work because MongoDB is expecting that _id is an ObjectId, and not a string (which req.params.id probably is):

var ObjectId = require('mongoose').Types.ObjectId;

exports.getUser = function (req, res) {
  var id  = req.params.id;
  var $or = [ { username : id } ];

  // Does it look like an ObjectId? If so, convert it to one and
  // add it to the list of OR operands.
  if (ObjectId.isValid(id)) {
    $or.push({ _id : ObjectId(id) });
  }

  User.find({ $or : $or }).exec(function (err, collections) {
    // TODO: check for errors
    res.send(collections);
  });
};

Find by id or username in mongo

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