Writing app logic in custom model strongloop

Hi i am new to strongloop i want to know can i write my app logic inside a custom model. Like in example below i am getting data from orders table and on success i want to use its response in my logic.

Orders.createOrder = function(cb) {
Orders.findById( userId, function (err, instance) {
    response = "Name of coffee shop is " + instance.name;
    cb(null, response);

/***** want to write my logic here *****/


    console.log(response);
});
cb(null, response);
};
Orders.remoteMethod(
'createOrder',
{
  http: {path: '/createOrder', verb: 'get'},
  returns: {arg: 'status', type: 'string'}
}
);

so is it the write place to do it or i have to write it somewhere else?

Solution

Your code has several issues, but the answer is pretty much yes.

You should call the callback function cb when your application logic is done, and not before. Also, you should pay attention to feed any errors to the cb, otherwise you're in for some big debugging headaches down the road.

Also, you need to pay extra attention to the way you're calling callbacks. In your current code, cb will be called twice for any request, at the very end of createOrder and in findById. This is not good, because for one request you tell the server you have completed two. Also, the callback at the end of createOrder is called immediately, before findById is complete.

So corrected code would look like this

Orders.createOrder = function(cb) {
  Orders.findById( userId, function (err, instance) {
    // Don't forget stop execution and feed errors to callback if needed
    // (other option : if errors are part of normal flow, process them and continue of course)
    if (err) return cb(err);
    
    response = "Name of coffee shop is " + instance.name;
    console.log(response);
    
    // Application logic goes there
    
    // Complete the remote method
    cb(null, response);
  });
  // No calls here to the callback
};
Orders.remoteMethod(
'createOrder',
{
  http: {path: '/createOrder', verb: 'get'},
  returns: {arg: 'status', type: 'string'}
}
);