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 controller? Similar to how ActionMailer does?

Thanks!

Answer 1

In Rails 5:

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

In Rails 6.1:

lookup_context = ActionView::LookupContext.new(ActionController::Base.view_paths)
context = ActionView::Base.with_empty_template_cache.new(lookup_context, {}, nil)

renderer = ActionView::Renderer.new(lookup_context)
renderer.render(context, { file: 'app/views/template.html.erb' })

• ActionView::Renderer.new() takes a lookup_context arg, and render() method takes a context, so we set those up first
• ActionView::Base is the default ActiveView context, and must be initialized with with_empty_template_cache method, else render() will error
• The {}, nil are required assigns and controller args, which used to default to {}, nil in Rails 5
• Rails 6.1 requires a full filepath file: 'app/views/template.html', whereas Rails 5 only required the filename