Helper or ???

rubyonrails-talk
1

I have a strong handle on when to use a helper -- at least I think so. A helper may include some logic (not enough to belong in the model) and it presents html as its output. So I have a conceptual problem about this solution that I've built:

#helpers/people_helper.rb   def person_roles     (%W(assistant author collector editor foreword illustrator interviewer introduction narrator notes translator) + Role.group('name').map(&:name)).uniq().sort   end

I use the output in a view, as part of a collection_select picker for a string-based attribute. This picker has a JavaScript "combobox" behavior added to it, so the editor can add new roles to the list at whim. But the output is an array. Does this invalidate my use of a helper method? Or am I thinking too much about the label "helper" here?

Thanks,

Walter

2

I have a strong handle on when to use a helper -- at least I think so. A helper may include some logic (not enough to belong in the model) and it presents html as its output. So I have a conceptual problem about this solution that I've built:

#helpers/people_helper.rb def person_roles (%W(assistant author collector editor foreword illustrator interviewer introduction narrator notes translator) + Role.group('name').map(&:name)).uniq().sort end

I use the output in a view, as part of a collection_select picker for a string-based attribute. This picker has a JavaScript "combobox" behavior added to it, so the editor can add new roles to the list at whim. But the output is an array. Does this invalidate my use of a helper method? Or am I thinking too much about the label "helper" here?

To me that looks more like something that should be called in the controller and go into an @ variable for use in the view. The general rule is setup data in the controller and display it in the view. The method itself could go in the Role model or in a module in lib

Colin

3

I had it in the controller, but I didn't like the look of having to declare an instance variable inside each method that needed this (new and create and edit and update). The helper was there for the asking in each view, so it seemed DRYer. Is there a way to have my cake and eat it too?

Thanks,

Walter

4

I have a strong handle on when to use a helper -- at least I think so. A helper may include some logic (not enough to belong in the model) and it presents html as its output. So I have a conceptual problem about this solution that I've built:

#helpers/people_helper.rb def person_roles (%W(assistant author collector editor foreword illustrator interviewer introduction narrator notes translator) + Role.group('name').map(&:name)).uniq().sort end

I use the output in a view, as part of a collection_select picker for a string-based attribute. This picker has a JavaScript "combobox" behavior added to it, so the editor can add new roles to the list at whim. But the output is an array. Does this invalidate my use of a helper method? Or am I thinking too much about the label "helper" here?

To me that looks more like something that should be called in the controller and go into an @ variable for use in the view. The general rule is setup data in the controller and display it in the view. The method itself could go in the Role model or in a module in lib

Colin

I had it in the controller, but I didn't like the look of having to declare an instance variable inside each method that needed this (new and create and edit and update). The helper was there for the asking in each view, so it seemed DRYer. Is there a way to have my cake and eat it too?

If it is the same code in each action then set the variable in a before_filter in the controller. Then it will be setup for each action that you specify. Bone dry.

Colin

5

helper_method :my_controller_method

?

6

Michael: I don't think that addresses the problem, unless I misunderstand. The OP doesn't need the method available in the controller *and* the view, he is just not sure about which it should be.

Colin

7

I had it in the controller, but I didn't like the look of having to declare an instance variable inside each method that needed this (new and create and edit and update). The helper was there for the asking in each view, so it seemed DRYer. Is there a way to have my cake and eat it too?

helper_method :my_controller_method

?

If it is the same code in each action then set the variable in a before_filter in the controller. Then it will be setup for each action that you specify. Bone dry.

Colin

Thanks to both of you.

Walter

8

True... depending on where it's wanted will affect whether it should be a helper, helper_method or before_filter :wink:

9

…

To me that looks more like something that should be called in the

controller and go into an @ variable for use in the view. The general

rule is setup data in the controller and display it in the view.

TL;DR

  • controller only does “routing/decision” logic (render, error, redirect, …)
  • views get their rich data from a presenter

I feel less confident about this strategy.

I have doubts over this code in the controller that is “pushing/pre-setting” data into e.g. a @user instance variable

@user = User.include(:account).include(:address).include(:projects).find(params[:id])

of which a large fraction may remain unused and the specific usage may change over time.

Suppose that we initially show a list of all the projects of the user in the show view, but later decide to not show that list in the first

“show” view anymore (it could e.g. be shown later with an AJAX request when the user opens a projects tab).

Then we would be always populating the @user with too much data, unless we think about removing that from the controller.

I would prefer a method where the view “pulls” (only) the data that it needs, when it needs it, from … (a presenter ??).

A helper (in my opinion) is purely an html/decorator thing (as was also the feeling of the OP, If I understood correctly).

Of course, the ActiveRecord::Relation helps to delay the actual SQL in certain cases (e.g. in the index view). But it does not remove the code complexity and potential inefficiency from the controller.

I start to feel more that the controller does some “routing/decision”

logic (render, error, redirect, …), but that it should not really prepare the data for later views. The views should “pull” their data from a presenter.

Does this make sense? Would it address the initial question from the OP?

Peter

10

I think the issue there is where there may be multiple ways of "viewing" the data. For example xml and html. In that case the conventional MVC concept is that the controller prepares the data then it goes off to an appropriate renderer which decides how to format it. In your example above with user projects, if only a subset of the projects is to be seen then it is up to the controller to make that subset available.

Colin

Colin

11

... To me that looks more like something that should be called in the controller and go into an @ variable for use in the view. The general rule is setup data in the controller and display it in the view.

TL;DR * controller only does "routing/decision" logic (render, error, redirect, ...) * views get their rich data from a presenter

I feel less confident about this strategy.

I have doubts over this code in the controller that is "pushing/pre-setting" data into e.g. a @user instance variable

@user = User.include(:account).include(:address).include(:projects).find(params[:id])

of which a large fraction may remain unused and the specific usage may change over time.

Suppose that we initially show a list of all the projects of the user in the show view, but later decide to not show that list in the first "show" view anymore (it could e.g. be shown later with an AJAX request when the user opens a projects tab).

Then we would be always populating the @user with too much data, unless we think about removing that from the controller.

I would prefer a method where the view "pulls" (only) the data that it needs, when it needs it, from ... (a presenter ??).

A helper (in my opinion) is purely an html/decorator thing (as was also the feeling of the OP, If I understood correctly).

Of course, the ActiveRecord::Relation helps to delay the actual SQL in certain cases (e.g. in the index view). But it does not remove the code complexity and potential inefficiency from the controller.

I start to feel more that the controller does some "routing/decision" logic (render, error, redirect, ...), but that it should not really prepare the data for later views. The views should "pull" their data from a presenter.

Does this make sense? Would it address the initial question from the OP?

Yes and yes. I agree with your analysis of my question, and I'd love to see more elucidation of how a presenter pattern could work in this case.

Thanks,

Walter