same html elements rendering twice on page

rubyonrails-talk
1

hey all,

My index.html.haml:

- wrap do   - page_title "Teams List View"

application_helper.rb:

  def page_title(title)     content_tag :h1, title   end

  def wrap(&block)     concat(content_tag(:div, capture(&block), :class => "generic_header"))   end

I load in browser and get: <div class="generic_header"><h1>Teams List View</h1></div> <div class="generic_header"><h1>Teams List View</h1></div>

It's rendered twice. Not sure why. I invoke the wrap iterator, passing a block into the argument list, wrap receivers it as a reference, then I concat a div, use capture to render the page title as nested within div, and assign div class. Not sure what I am doing wrong.

2

What happens if you get rid of concat()?

3

By the way, if you put some html at the top of the page, e.g.

%p Index.html.haml - wrap do   - page_title "Teams List View"

Your wrap() method will double render the whole page.

Based on my experiments with haml, I would never consider using a multiline ruby block that contains a rails helper. The results are too unpredictable. Both of these syntaxes do what you want (without concat):

- wrap do   - page_title "Teams List View"

- wrap do   = page_title "Teams List View"

Note that in this code:

content_tag(:div, capture(&block), :class =>"generic_header")

...capture() does indirectly what block.call() does directly.

4

thanks for response, and the explanation of capture(). When I removed the concat from the helper, the title stopped rendering twice. I thought the concat was used to concatenate the two blocks of html, but after reading documentation it appears it's to render haml without using "=".

5

It seems to me that the = sign in haml is arbitrary and capricious. For instance, how does the syntax:

- wrap do   - page_title "Teams List View"

result in anything being added to the page?