Undefined method stupidity

Rails
1

I put some code in a before_save callback in the model file to alter
some fields that have dependencies in the DB.

I’d like to call a method in the controller file but I continually get
undefined method errors. I have specified Controller::methodname as well
to no avail. What am I missing?

2

Say you have your object is my_obj.

Then do my_obj.before_save

3

Maybe I wasn’t clear. I have a routine I’d like to invoke FROM the
before_save callback.

I’d like to place the routine in the controller file rather than in the
model.

When I move it I continually get undefined method. Sorry for the
confusion.

4

Mike K. wrote:

Maybe I wasn’t clear. I have a routine I’d like to invoke FROM the
before_save callback.

I’d like to place the routine in the controller file rather than in the
model.

When I move it I continually get undefined method. Sorry for the
confusion.

Why do you think it belongs in a controller? Once the flow of control
has entered the model, you shouldn’t be trying to jump back up into the
controller layer.

Technically, you migt be able to solve your problem by using a class
method on the controller. Architecturally, this probably wouldn’t be the
right thing to do.

regards

Justin

5

Justin F. wrote:

Why do you think it belongs in a controller? Once the flow of control
has entered the model, you shouldn’t be trying to jump back up into the
controller layer.

Technically, you migt be able to solve your problem by using a class
^^^^ might

6

Thank you Peter. Let me give you a couple of scenarios. I was also just
reflecting what someone advised me to do in another thread – perhaps it
wasn’t the best advice.

I have a little fishing tournament app with a Catch table where all the
catches go. Each catch has a length, from which points are determined.
Depending on the bait (live, artificial, fly) we give a points
adjustment (eg: 10% for lures, 20% for using fly tackle). So I was
trying to update the points field from the size input by the user.
Initially I was doing this in the Catch controller both in the new catch
method and the update/edit method, and I had a bug due to the fact that
I was referencing the old points in the DB record which hadn’t been
committed yet. I got some advice to try the bfore_save callback and
while that worked, the advisor also said it would be more “proper”
MVC-wise to put the actual code in the controller and invoke it from the
model. Thus, I got into this connundrum of trying to figure out how to
make that work and got into undefined method issues.

As far as syntax styles, deprecated APIs etc, what bites is that EVERY
tutorial and example on RoR uses the “old style” APIs such as find_all
etc rather than find (:all), so there is quite a limited # of examples
using the “proper” API (some Ruby but not RoR). I find it particularly
lacking that the API reference does not show more examples of the syntax
in use. It’s not productive having to learn the same thing 2x, 3x. Now I
have to go recode everything to the proper API :wink:

7

Mike,

You should never invoke a controller method from a model directly.
You can’t assume that a controller exists when your model is called.
Perhaps if you explain a little more about what you’re trying to
achieve, someone can suggest an appropriate solution.

Pete Y.
http://9cays.com/

8

Mike K. wrote:

method and the update/edit method, and I had a bug due to the fact that
I was referencing the old points in the DB record which hadn’t been
committed yet. I got some advice to try the bfore_save callback and
while that worked, the advisor also said it would be more “proper”
MVC-wise to put the actual code in the controller and invoke it from the
model. Thus, I got into this connundrum of trying to figure out how to
make that work and got into undefined method issues.

I think if you re-read that advice you will see that the adviser (Chris
Carter) said “you really should put that calculation in the model, not
in the controller, then call it from the controller. This will keep
your code clean and DRY, and makes it more MVCish/Railsish.”.

As far as syntax styles, deprecated APIs etc, what bites is that EVERY
tutorial and example on RoR uses the “old style” APIs such as find_all
etc rather than find (:all), so there is quite a limited # of examples
using the “proper” API (some Ruby but not RoR). I find it particularly
lacking that the API reference does not show more examples of the syntax
in use. It’s not productive having to learn the same thing 2x, 3x. Now I
have to go recode everything to the proper API :wink:

It is a problem that Rails evolves very fast, leaving the tutorials
beind. The API documentation gives a reasonable set of examples for
find:

ActiveRecord::Base

regards

Justin

9

Oops, guess I got it backwards. Good, then I am doing it right!

10

Mike K. wrote:

Oops, guess I got it backwards. Good, then I am doing it right!

Keep it up!

:slight_smile:

Justin