Same html elements rendering twice on page

Rails
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:

Teams List View

Teams List View

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

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 “=”.

4

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. All of these syntaxes do what you want (without
concat):

= wrap {page_title “Teams List View”}

  • wrap do

    • page_title “Teams List View”

  • wrap do
    = page_title “Teams List View”

Curiously, this does not work:

  • wrap {page_title “Teams List View”}

which doesn’t make any sense in light of the second syntax above.

Note that in this code:

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

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

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?