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Parts of template are rendered twice, induced by yield or cache
Reported by Jan | December 11th, 2010 @ 12:29 PM
When I use a helper method, that yields to a given content block, the surrounding(!) template is rendered twice above where the helper is used. Rails 3.0.3.
Standard layout:
<!DOCTYPE html>
<html>
<head>
<title>Foo</title>
<%= stylesheet_link_tag :all %>
<%= javascript_include_tag :defaults %>
<%= csrf_meta_tag %>
</head>
<body>
<%= yield %>
</body>
</html>
Helper:
def foo(&block)
yield
end
Template:
<p>TOP</p>
<%- foo do -%>
<p>YIELDED STUFF</p>
<%- end -%>
<p>BOTTOM</p>
Output:
TOP
YIELDED STUFF
TOP
YIELDED STUFF
BOTTOM
I'm having this same issue with cache do:
<p>TOP</p>
<%- if false; cache do -%>
Something
<%- end; else -%>
foobar
<%- end -%>
<p>BOTTOM</p>
Output:
TOP
foobar
TOP
foobar
BOTTOM
The double rendering does NOT occur like this:
<p>TOP</p>
<%- if false -%>
Something - without cache
<%- else -%>
foobar
<%- end -%>
<p>BOTTOM</p>
Or this:
<p>TOP</p>
<%- if true; cache do -%>
Something - note the TRUE in this version
<%- end; else -%>
Bar
<%- end -%>
<p>BOTTOM</p>
Comments and changes to this ticket
-
Piotr Sarnacki December 11th, 2010 @ 02:37 PM
- Importance changed from “” to “Low”
You need to use capture in your helper:
def foo(&block) capture(&block) endAnd add = in front of the call in view:
<%= foo do -%> Something <% end -%>As of second example, I think that this is based on implementation of <%= block_helper do %> in Rails 3:
https://github.com/rails/rails/blob/master/actionpack/lib/action_vi...I don't know if this can be fixed, as for now you should use that form:
<%- if false -%> <%= cache do -%> Something <%- end -%> <%- else -%> foobar <%- end -%> -
Jan December 12th, 2010 @ 08:21 AM
Well, the cache thing was my real problem, the other one was just how I tried to understand what might be going wrong. So thanks for pointing out my mistakes! I already went a little crazy.
-
Jan December 12th, 2010 @ 08:48 AM
API and guide use <% cache do %> without =.
http://api.rubyonrails.org/classes/ActionView/Helpers/CacheHelper.h...
http://guides.rubyonrails.org/caching_with_rails.html#fragment-caching -
Piotr Sarnacki December 12th, 2010 @ 10:23 AM
- State changed from “new” to “invalid”
I think that cache works both with = and without, probably it just writes to @output_buffer and returns nil, so = does not change anything. I just thought that it needs it. Seems like a little bit inconsistent, though.
I think this can be closed and I'll start a discussion on block helpers on rails group later.
-
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Jan
Jeremy Kemper
Piotr Sarnacki