Undefined method `template_options_for` within an Engine

[ElliottAYoung]

I am using cells ~> 4.1 in a Rails engine that has no expectation of the base application to have cells installed. I have the following gems included as dependencies in my .gemspec:

  s.add_dependency "rails", ">= 4"
  s.add_dependency "cells", "~> 4.1"
  s.add_dependency "cells-rails", "~> 0.0.6"
  s.add_dependency "cells-haml", "~> 0.0.10" 

As of right now I have a relatively basic setup with one cell class, HelloWorldCell, this is the source so far:

   class HelloWorldCell < Cell::ViewModel
     view_paths << "#{MyEngineName::Engine.root}/app/cells"

     def show
        render
     end
   end

In the corresponding view slot for this cell I have exactly one view show.haml that has basic hall markup to simply say "Hello World". When I try to load this cell in a paired Rails app I consistently get the following error:

NoMethodError: undefined method `template_options_for' for #<HelloWorldCell:0x007f83c61d8d90>
Did you mean?  template_for from #{PATH}

Is there some piece I'm missing from this to get the views to render when called when using cells in an engine?

Thank you!

[apotonick]

Hi El, you need to include the respective cell format module into the cells.

class Hello < Cell::ViewModel
  include Cell::Haml

Two things: please use trailblazer-cells wherever you can to stay forward compatible (only a few things in the behavior have changed) and avoid Haml wherever you can, it's dead, use Slim.

[ElliottAYoung]

Perfect, thank you very much!

[TheFlow0360]

I'm having this problem, too, just with ERB. I'm not including Cell::Erb in my ViewModel since the README states this isn't necessary when using Rails. Also, I tried including it anyways and got another error: uninitialized constant Cell::Erb (even though I have spec.add_dependency "cells-erb", "~> 0.1" in my gemspec).

@ElliottAYoung Is the project you are working on public? I'm also trying to create an Engine as a gem that uses Cells and any guidance would be really helpful. It would be great, if you could point out resources you used to find out best practices etc.

EDIT: i fixed it, I needed to do the include Cell::Erb but was missing a require "cell/erb"

[ElliottAYoung]

@TheFlow0360 The project is public, you can access it here: https://github.com/ElliottAYoung/funfetti

I haven't done a whole lot with it yet / written sufficient documentation, so I do apologize for that. But you should be able to see all relevant examples for including cells in an engine in /app/cells/funfetti/cell.rb and see examples for how to call this in lib/confetti

[TheFlow0360]

@ElliottAYoung thanks a lot, I'll take a look!