Guides

Menu Presenter

10 minutes and 59 seconds read.

Additional Menus

This guide will show you how to:

  • configure and use Refinery::Pages::MenuPresenter
  • use a decorator to add custom functionality to Refinery::Page class
  • use a decorator to allow attributes in Refinery::Admin::PagesController
  • override Refinery's view

Requirements

Let's start with requirements. I tried to bring them together in the following steps:

  • We need to add an additional navigation menu in the footer section of each page right above Refinery's copyright notice.
  • Admin should be able to specify which pages appear in the footer menu, so we also need to add a checkbox under "Advanced options" in the page edit form.
  • Data about whether page shows up in the footer should be persisted to the database.

Alright, it's time to dive deep into the code.

The requirement was to persist the data to the database, so we will start by creating a migration that a will add refinery_pages column to the refinery_pages database table.

Open up terminal and type:

rails generate migration add_show_in_footer_to_refinery_pages

This will generate an empty migration. Open it and add the following code:

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class AddShowInFooterToRefineryPages < ActiveRecord::Migration
  def change
    add_column :refinery_pages, :show_in_footer, :boolean, default: false
  end
end

Run the migration:

rake db:migrate

Decorating the Refinery::Page model

We want to decorate the Refinery::Page class.

Create a file app/decorators/models/refinery/page_decorator.rb with this content:

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Refinery::Page.class_eval do
  def self.footer_menu_pages
    where show_in_footer: true
  end
end

We added footer_menu_pages class method to abstract away ActiveRecord query method.

Before overriding Refinery's form view, we want to decorate the Refinery::Admin::PagesController class.

Create a file app/decorators/controllers/refinery/admin/pages_controller_decorator.rb with this content:

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Refinery::Admin::PagesController.prepend(
  Module.new do
    def permitted_page_params
      super << :show_in_footer
    end
  end
)

We added show_in_footer to the permitted attributes list so that it doesn't raise a mass-assignment error each time someone tries to save the page.

Overriding the form view

As I previously mentioned, let's make it so that a "Show in footer" checkbox appears right after Admin expands the "Advanced options" when editing a page.

To do this, we have to override the file _form_extra_fields_for_more_options.html.erb partial.

Type this in the terminal:

rake refinery:override view=refinery/admin/pages/_form_extra_fields_for_more_options.html

Now open the _form_extra_fields_for_more_options.html.erb partial and add the following code right after the commented line:

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<div class='field'>
  <span class='label_with_help'>
   <%= f.label :show_in_footer, "Show in footer" %>
   </span>
   <%= f.check_box :show_in_footer %> Show this page in the footer menu
</div>

Creating and configuring the Presenter

Now let's focus on the presenter itself. Once instantiated, it is also possible to configure its CSS/HTML using this instance. We will use a Rails helper to instantiate a new instance of Refinery::Pages::MenuPresenter and also configure it there. We're taking this approach because we don't want to pollute the view with configuration code.

Open the ApplicationHelper file in app/helpers/application_helper.rb and add this code:

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def footer_menu
  menu_items = Refinery::Menu.new(Refinery::Page.footer_menu_pages)

  Refinery::Pages::MenuPresenter.new(menu_items, self).tap do |presenter|
    presenter.dom_id = "footer_menu"
    presenter.css = "footer_menu"
    presenter.menu_tag = :div
  end
end

We create an instance of Refinery::Menu by passing a collection of footer pages (Refinery::Page.footer_menu_pages) to it. We need it because it will be the data that will be "presented" by Refinery::Pages::MenuPresenter. We assign this instance to a variable called presenter in order to configure this presenter. I want my footer menu to be wrapped inside of a div tag instead of the default nav tag and I also want it to have a CSS class and an ID of footer_menu instead of the default menu one:

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presenter.dom_id = "footer_menu"
presenter.css = "footer_menu"
presenter.menu_tag = :div

Now that we have configured the menu presenter we need to return it because we'll have to call .to_html on it in the view later on.

Rendering the Menu in the View

Requirement was for the footer menu to appear just above Refinery's copyright notice. To do that we will simply override Refinery's footer view:

rake refinery:override view=refinery/_footer.html

Next, add this code in the footer partial, above the existing code:

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<%= footer_menu.to_html %>

Taking a look at it

Now it's time to take a look at how everything is working. Edit a couple of pages and for some of them check the "Show in footer" checkbox located under "Advanced options". Now go to the root url of your site and take a look at the bottom; you should see links for the pages for which you checked the "Show in footer" checkbox. Also here's how the generated HTML should look:

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<div class="footer_menu" id="footer_menu">
  <ul>
    [...]
  </ul>
</div>