How do I render a partial of a different format in Rails?

Question

I'm trying to generate a JSON response that includes some HTML. Thus, I have /app/views/foo/bar.json.erb:

{
  someKey: 'some value',
  someHTML: "<%= h render(:partial => '/foo/baz') -%>"
}

I want it to render /app/views/foo/_baz.html.erb, but it will only render /app/views/foo/_baz.json.erb. Passing :format => 'html' doesn't help.

Answer 1

You have two options:

1) use render :file => "foo/_baz.json.erb"

2) change template format to html by setting @template_format variable

<% @template_format = "html" %>
<%= h render(:partial => '/foo/baz') %>

Answer 2

Building on roninek's response, I've found the best solution to be the following:

in /app/helpers/application.rb:

def with_format(format, &block)
  old_format = @template_format
  @template_format = format
  result = block.call
  @template_format = old_format
  return result
end

In /app/views/foo/bar.json:

<% with_format('html') do %>
  <%= h render(:partial => '/foo/baz') %>
<% end %>

An alternate solution would be to redefine render to accept a :format parameter.

I couldn't get render :file to work with locals and without some path wonkiness.

Answer 3

What's wrong with

render :partial => '/foo/baz.html.erb'

? I just tried this to render an HTML ERB partial from inside an Atom builder template and it worked fine. No messing around with global variables required (yeah, I know they have "@" in front of them, but that's what they are).

Your with_format &block approach is cool though, and has the advantage that you only specify the format, whereas the simple approach specifies the template engine (ERB/builder/etc) as well.

Answer 4

I came across this thread when I was trying to render an XML partial in another xml.builder view file. Following is a nice way to do it

xml.items :type => "array" do
    @items.each do |item|
        xml << render(:partial => 'shared/partial.xml.builder', :locals => { :item => item })
    end
end

And yeah... Full file name works here as well...

Answer 5

For Rails 3, the with_format block works, but it's a little different:

  def with_format(format, &block)
    old_formats = formats
    self.formats = [format]
    block.call
    self.formats = old_formats
    nil
  end