jeremyevans/roda

Problem using ERB blocks within content_for

njh opened this issue · 4 comments

njh commented

I have been having trouble with not being able to use ERB blocks within a content_for block. It is slightly tricky to describe in words, so I have created a example, which hopefully illustrates the problem. Please let me know if it isn't clear.

Test App

/config.ru

require 'roda'
require 'erubi'

class App < Roda
  plugin :render, :escape => true
  plugin :content_for

  route do |r|

    r.root do
      @hash = {:a => 1, :b => 2, :c => 3}
      view('homepage')
    end
  end

end

run App.freeze.app

/views/homepage.erb

<% content_for :page_title, 'Home' %>
<% content_for :head do %>
  <link rel="canonical" href="http://www.example.com/" />
  <% @hash.each_pair do |key,value| %>
    <meta name="<%= key %>" content="<%= value %>" />
  <% end %>
<% end %>

Hello World

/views/layout.erb

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8" />
  <title><%= content_for :page_title %></title>
  <%== content_for :head %>
</head>
<body>
  <h1><%= content_for :page_title %></h1>
  <%== yield %>
</body>
</html>

Expected Result

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8" />
  <title>Home</title>
  <link rel="canonical" href="http://www.example.com/" />
   <meta name="a" content="1" />
   <meta name="b" content="2" />
   <meta name="c" content="3" />
</head>
<body>
  <h1>Home</h1>
  
Hello World

</body>
</html>

Actual Result

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8" />
  <title>Home</title>
  {:a=>1, :b=>2, :c=>3}
</head>
<body>
  <h1>Home</h1>
  
Hello World

</body>
</html>

Dependency versions:

  • erubi (1.7.1)
  • rack (2.0.6)
  • roda (3.14.0)
  • tilt (2.0.8)
jeremyevans commented

content_for stores the value the block returns, and in your case that is the return value of hash.each_pair, which is the hash itself. To workaround that, try adding an extra line before the end of the content_for block and see if that fixes the issue.

It is possible to modify the content_for plugin to support always using the temporary template output buffer as the return value instead of the result of the block, but it would break when a non-ERB template engine is used. I suppose that could be made conditional on the template engine. Can you try this patch and let me know if it fixes your issue?

diff --git a/lib/roda/plugins/content_for.rb b/lib/roda/plugins/content_for.rb
index 993ff1f..974a105 100644
--- a/lib/roda/plugins/content_for.rb
+++ b/lib/roda/plugins/content_for.rb
@@ -63,6 +63,9 @@ class Roda
               # Use temporary output buffer for ERB-based rendering systems
               instance_variable_set(outvar, String.new)
               value = Tilt[render_opts[:engine]].new{yield.to_s}.render
+              if render_opts[:engine] == 'erb'
+                value = instance_variable_get(outvar)
+              end
               instance_variable_set(outvar, buf_was)
             end
njh commented

Thanks for the fast response.

Yes, an extra line before the end of the content_for block does work.
I thought I had tried that before, but clearly not.

And your patch also works for me - I think it will make the behaviour in an ERB template less 'surprising'!

jeremyevans commented

Unfortunately, the patch would break the case where you use a block normally without a template:

content_for(:foo){"bar"}

So I think the documentation needs to be clear that the content stored is the block output, and to discuss this issue and how to work around it.

  • 👍1
njh commented

Thanks Jeremy!

BTW, I built this website using Roda, Sequel and Erubi:
https://www.radiodns.uk/

Thanks for all the nice Open Source things you have made 🙂