Rails: Make Route Helper Methods Available to PORO

Question

Within a Plain Old Ruby Object (PORO) in my rails app: I have the following method:

def some_method
  content_tag(:li, link_to("Do something", somewhere_path(object.id)))
end

First: the object didn't understand the method content_tag, so I added the following which made the object understand that method:

include ActionView::Helpers::TagHelper

Then the object didn't understand link_to so I added the following which made the object understand that method:

include ActionView::Helpers::UrlHelper

Now, it doesn't understand my route: somewhere_path(object.id).

Question: How can I make the PORO in my rails app understand the helpers which generate routes?

Followup Question: Is there an easier way to include all of this functionality into my PORO object? Perhaps there is a way to only include one major module and get all of this functionality (as opposed to perhaps needing to require 3 different modules).

@tadman no I literally ment the the method `init`. I answered my own question below, so you can see what the class would look like. — Neil, May 10 '17 at 04:07
Having `init` and `initialize` is asking for confusion, especially as in other languages `init` is what the initializer method is called. — tadman, May 10 '17 at 04:08

score 6 · Accepted Answer · edited May 23 '17 at 10:31

You either have to do what you describe in your self-answer (link to revision I refer to), or inject some context into your POROs. Where context is something which knows all those methods. Something like this:

class ProjectsController
  def update
    project = Project.find(params[:id])
    presenter = Presenters::Project.new(project, context: view_context) # your PORO
    # do something with presenter
  end
end

And your PORO would look like this:

module Presenters
  class Project
    attr_reader :presentable, :context
    def initialize(presentable, context:)
      @presentable = presentable
      @context = context
    end

    def special_link
      context.somewhere_path(presentable)
    end
  end
end

Me, I like neither of them. But sometimes we have to choose a lesser evil.

If anyone happens to know of a current way to get access to all of these methods with one include statement then let me know.

Why, yes. There is a way.

module MyViewCompatibilityPack
  include ActionView::Helpers::TagHelper
  include ActionView::Helpers::UrlHelper

  def url_helpers
    Rails.application.routes.url_helpers
  end
end

class MyPoro
  include MyViewCompatibilityPack

  ...
end

see my updated answer. Let me know if you know of how to do this becuase it appears as though it just isn't possible inside a PORO object. — Neil, Apr 22 '17 at 04:30
I updated my answer yet again. See above. Also, I believe your answer will not "always" build the paths right via `Rails.application.routes.url_helpers`. I ran into issues while using passenger, as it didn't know the domain. — Neil, May 10 '17 at 04:23
Yeah, in these situations, you should specify the host explicitly. Or set it [like this](http://stackoverflow.com/a/5725343/125816). — Sergio Tulentsev, May 10 '17 at 07:03

Neil · Answer 2 · 2017-05-10T04:11:06.180

0

The issue is that actionview-related methods are not available to POROs.

In order to get all the great stuff from actionview: you need to utilize the view_context keyword. Then: you can simply call upon actionview-related methods from your view_context:

class BuildLink
  attr_accessor :blog, :view_context

  def initialize(blog, view_context)
    @blog = blog
    @view_context = view_context
  end

  def some_method
    content_tag(:li, link_to(“Show Blog“, view_context.blog_path(blog)))
  end
end

So for example: from your controller you would call upon this PORO like so:

BuildLink.new(@blog, view_context).some_method

For more information, see below references:

Rails doc on view_context
Utilization of view_context via presenter pattern, shown in this article
Railscast which talks through utilizing view_context via presenter pattern

edited May 10 '17 at 04:11

answered Apr 11 '17 at 20:50

Neil

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It's pretty dirty to self-post an answer and not even acknowledge what Sergio did with a simple upvote. He's also right, a presenter is what you're talking about. What you're doing here is highly irregular and not recommended. – tadman May 10 '17 at 04:10
his method has the limitation of not knowing the domain. Espcially if using passenger, the url will be wrong. Also: prior to updating my answer: I did post a comment to him and he did not respond back. "Dirty" is putting it pretty strong. – Neil May 10 '17 at 04:11
I think you're misunderstanding his code. There's a reason this sort of stuff doesn't leak out. If you want that sort of functionality, define helpers. This is exactly what they're for. – tadman May 10 '17 at 04:12

Rails: Make Route Helper Methods Available to PORO

2 Answers2