Rails: Render view from outside controller

Question

I\'m trying to create an HTML string using a view. I would like to render this from a class that is not a controller. How can I use the rails rendering engine outside a co

Answer 1

Technically, ActionMailer is a subclass implementation of AbstractController::Base. If you want to implement this functionality on your own, you'll likely want to inherit from AbstractController::Base as well.

There is a good blog post here: https://www.amberbit.com/blog/2011/12/27/render-views-and-partials-outside-controllers-in-rails-3/ that explains the steps required.

Answer 2

Rails 5 now supports this in a much more convenient manner that handles creating a request and whatnot behind the scenes:

rendered_string = ApplicationController.render(
  template: 'users/show',
  assigns: { user: @user }
)

This renders app/views/users/show.html.erb and sets the @user instance variable so you don't need to make any changes to your template. It automatically uses the layout specified in ApplicationController (application.html.erb by default).

The test shows a handful of additional options and approaches.

Answer 3

Best to render the view using a controller, as that's what they're for, and then convert it to a string, as that is your ultimate goal.

require 'open-uri'
html = open(url, &:read)

Answer 4

There is no need to over bloat your app with too many gems. As we know ERB is already included in your Rails app.

@jdf = JDF.new
@job = ERB.new(File.read(Rails.root + "app/views/entries/job.xml.erb"))
result =  @job.result(binding)

Above there is snippet of code of an app I'm working on.

• @jdf is a object to be evaluated in the erb view.
• In my case I needed to render xml.
• result is a string to be saved or sent anywhere you like.

Answer 5

You can use ActionView::Base to achieve this.

view = ActionView::Base.new(ActionController::Base.view_paths, {})
view.render(file: 'template.html.erb')

The ActionView::Base initialize takes:

1. A context, representing the template search paths
2. An assigns hash, providing the variables for the template

If you would like to include helpers, you can use class_eval to include them:

view.class_eval do
  include ApplicationHelper
  # any other custom helpers can be included here
end

Answer 6

Calling directly render method on ApplicationController may raise error

 Helper Devise: could not find the `Warden::Proxy` instance on request environment

Instead we can use ApplicationController.renderer.render like

 rendered_string = ApplicationController.renderer.render(
     partial: 'users/show',
     locals: { user: user }
)