Mongoose TypeError on a model's findOne method

Answer 1

It's known node.js issue. It means that you have looping require somewhere in your code and node.js forbids it.

The right way to do it is by using mongoose.model method. So, instead of UserModel variable you shall use mongoose.model('UserModel'). So, when findSomeUsers will be called mondoose will fetch UserModel and invoke its find method.

GroupSchema.statics.findSomeUsers = function(group, callback) {
    this.find({name : session_user._id}, function(err, groups) {
        mongoose.model('UserModel').find({_id : {$in : group.users}}, function(err,patients) {
            // do magic
        });
    });
};