title: Schema Error, 'has no method save'
body: <p>Currently What I want to do is, once the user is logged in he could go to any user's url and follow them. Im getting this problem</p>
  
  <pre><code>TypeError: Object { _id: 54bd6b90b7d4cc8c10b40cbd,
    name: 'Johnny',
    username: 'batman',
    __v: 0,
    following: [],
    followers: [] } has no method 'save'
  </code></pre>
  
  <p>schema.js</p>
  
  <pre><code>var UserSchema = new Schema({
      name: String,
      username: { type: String, required: true, index: { unique: true }},
      password: { type: String, required: true, select: false },
      level: String,
      followers: [{ type: Schema.Types.ObjectId, ref: 'User'}],
      following: [{ type: Schema.Types.ObjectId, ref: 'User'}]
  });
  
  module.exports = mongoose.model('User', UserSchema);
  </code></pre>
  
  <p>api.js</p>
  
  <pre><code>        // this is where I'm Stuck ( Should I use put or post? for best practices)
  
          .post(function(req, res) {
  
              // find a current user that has logged in
              User.find({ _id: req.decoded.id }, function(err, user) {
  
                  // simply follow the user by matching the id
                  user.following = req.params.user_id;
  
                  // save to the database ( The problem )
                  user.save(function(err) {
                      if(err) res.send(err);
  
                      res.json({ message: "Successfully followed!"})
                  })
              });
          })
  </code></pre>
  
  <p>The problem is in .post since I couldn't save. What should I do to make it save to the database?</p>