Use own helpers in Resource files

TL;DR

Run rails app:template LOCATION='https://railsbytes.com/script/V2Gsb9'

Details

A common pattern is to have some helpers defined in your app to manipulate your data. You might need those helpers in your Resource files.

Example:

Let's say you have a Post resource and you'd like to show a stripped-down version of your body field. So in your posts_helper.rb file you have the extract_excerpt method that sanitizes the body and truncates it to 120 characters.

# app/helpers/posts_helper.rb
module PostsHelper
  def extract_excerpt(body)
    ActionView::Base.full_sanitizer.sanitize(body).truncate 120
  end
end

Now, you'd like to use that helper inside one of you computed fields.

class Avo::Resources::Post < Avo::BaseResource
  def fields
    field :excerpt, as: :text do |model|
      extract_excerpt model.body
    end
  end
end

Initially you'll get an error similar to undefined method 'extract_excerpt' for #<Avo::Fields::TextField>. That's because the compute field executes that method in a scope that's different from your application controller, thus not having that method present.

The solution

The fix is to include the helper module in the BaseField and we can do that using this snippet somewhere in the app (you can add it in config/initializers/avo.rb).

# config/initializers/avo.rb
Avo.configure do |config|
  # Usual Avo config
end

module FieldExtensions
  # Include a specific helper
  include PostsHelper
end

Rails.configuration.to_prepare do
  Avo::Fields::BaseField.include FieldExtensions
end

Or you can go wild and include all helpers programatically.

# config/initializers/avo.rb
Avo.configure do |config|
  # Usual Avo config
end

module FieldExtensions
  # Include all helpers
  helper_names = ActionController::Base.all_helpers_from_path Rails.root.join("app", "helpers")
  helpers = ActionController::Base.modules_for_helpers helper_names
  helpers.each do |helper|
    send(:include, helper)
  end
end

Rails.configuration.to_prepare do
  Avo::Fields::BaseField.include FieldExtensions
end

Now you can reference all helpers in your Resource files.