Call a controller method from model

Rails
1

Hi people

I have a problem. I want to know if it is possible to call a method
(in the controller of a class) from an action, a callback or something
in a related model.

e.g.

Model A “has many” Model B

But every time Model A is updated I need to execute a (custom)
controller method in Model B

Hope you can help me

2

This is a bad idea. Models shouldn’t know about controllers at all.

What does the controller action do? Perhaps you can just do that in a
method
on a model.

3

Well, the example I used is a little simple for what I really need.

I have 4 models

Model A, Model B, Model C, and Model D

Everytime I update Model C, I have to update Model B
Everytime I update Model D, I have to update Model B

Everytime I update Model B, I have to update Model A, but this update
depends on “which” model has updated Model B. if Model C has updated
Model B I have to make some changes in Model A. But if Model D has
updated Model B I have to make differnts changes in Model A.

My problem is that I don’t know how can I recognize which model has
updated Model B to “switch” between actions to update Model A

4

On Thu, Aug 25, 2011 at 2:20 AM, Angelo C. [email protected]
wrote:

depends on “which” model has updated Model B. if Model C has updated
Model B I have to make some changes in Model A. But if Model D has
updated Model B I have to make differnts changes in Model A.

I think the simplest way to do this is to have an after_save callback on
ModelC and ModelD.
Just call the method that will update ModelB and ModelA on the
callbacks.

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5

Maybe you could use some sort of “updated by model” field on your Model
B.

In your controller (for example):

model_c = ModelC.find
model_c.save
model_b = ModelB.find
model_b.updated_by_model = ModelC

Then in your model, you could do something like this:

after_save :update_model_a

def update_model_a
model_a = ModelA.find
model_a.foo = “bar” if updated_by_model = ModelC
model_a.foo = “rab” if updated_by_model = ModelD
end

These are just very broad ideas since I don’t know the specifics.
Hopefully
they will spark some ideas for you, but it should be possible to do this
in
a more “railsy” way than calling a controller action from a model

6

Maybe you could use an Observer…

7

Angelo C. wrote in post #1018303:

Well, the example I used is a little simple for what I really need.

I have 4 models

Model A, Model B, Model C, and Model D

Everytime I update Model C, I have to update Model B
Everytime I update Model D, I have to update Model B

Everytime I update Model B, I have to update Model A, but this update
depends on “which” model has updated Model B. if Model C has updated
Model B I have to make some changes in Model A. But if Model D has
updated Model B I have to make differnts changes in Model A.

My problem is that I don’t know how can I recognize which model has
updated Model B to “switch” between actions to update Model A

Sounds like what you need is Key Value Observing (KVO). Too bad I know
of nothing like that anywhere in Rails. Plus it probably doesn’t make
sense in a web application anyway.

http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/KeyValueObserving/KeyValueObserving.html

Sorry, that wasn’t exactly helpful, but maybe an interesting…
observation (pun intended). :slight_smile:

8

Thank all of you for your help… Finally I solve my problem by doing
something really simple… I just made a subtraction and everything
work just fine

Thanks again

9

On Wed, Aug 24, 2011 at 11:20 AM, Angelo C. [email protected]
wrote:

Everytime I update Model B, I have to update Model A, but this update
depends on “which” model has updated Model B. if Model C has updated
Model B I have to make some changes in Model A. But if Model D has
updated Model B I have to make differnts changes in Model A.

One Adam 12, code 7, Law of Demeter violation in progress :slight_smile:

http://en.wikipedia.org/wiki/Law_of_Demeter

You might want to rethink these models. Just sayin’ …

–
Hassan S. ------------------------ [email protected]

twitter: @hassan