Updating a waterline model from an instance method - node.js

Question

I am using the Waterline ORM to interface with my database.
I am extend Waterline.Collections into a new objects and assign them to a module:
var Waterline = require('waterline');
var User = Waterline.Collection.extend({
...some fields...
attributes:{
col_a:{
type:'integer'
},
touch_user:function(){
// increment col_a and update in table
}
}
});
export = module.exports = User;
I query for the specific models I need to update, then manipulate them in a promise.
database.models.users.findAll().where({'id':1}).then(...model manipulation...)
There is a task I perform often, almost whenever I access the model. I would like to encapsulate this task in a function associated with the instance so I can simple call "touch_user" and the relevant fields will be updated for the model i call it on.
I am not able to access the Waterline query methods (such as .update()) from the model instance after a model is queried like so:
database.models.users.findAll().where({'id':1).then((user)=>{
user.touch_user();
//user.update // does not work
});
But it is not until I query it that I retrieve the data associated with the record.
I would like user.touch_user() to increment col_a in the users table similar to the following
database.models.users.findAll().where({'id':1).then((user)=>{
user.touch_user();
database.models.users.update(user.id, {'col_a':user.col_a+1});
});
The problem with the above is that the user object does not accurately reflect the update to the table.

Answer 1

What I ended up doing was creating a class method to update the model and the instance. Not exactly what I want, but it does in a pinch to keep the model and table synced
var User = Waterline.Collection.extend({
...some fields...
attributes:{
col_a:{
type:'integer'
},
},
// touch_user is a class method here
touch_user:function(user){
// update model instance
user.col_a += 1;
// update database table
database.models.users.update(user.id, {'col_a':user.col_a).exec(function(){});
}
});
Called like so
database.models.users.findAll().where({'id':1).then((user)=>{
...modify user...
database.models.users.touch_user(user);
...other changes to user that have to occur here...
database.models.users.touch_user(user);
});