Instance variable looses value upon render

Rails
1

I have an instance variable, @pages, which needs to be set up in a
certain way at the end of several actions, so I thought to be clever and
do it in the following way:

In my controller

after_action :prepare_admin_home_data, only:
[:adm_login,:adm_upload_selected]

def adm_login
…
render admin_pages_home_path
…
end

def prepare_admin_home_data
@pages=Dir["#{AMP_DIR}/*"]
logger.debug("+++++++++++ pages #{@pages.to_s}")
end

I can see from the logs, that @pages got the right value, but in my
view, it is nil. It seems that the HTML code is constructed before the
after_action is executed.

I understood the render() function in that way, that it only sets up
which ERB template is supposed to be used, but actual rendering would
occur only when the action has finished. Did I get this wrong?

Ronald

2

On Wednesday, 8 October 2014 11:07:16 UTC-4, Ruby-Forum.com User wrote:

def adm_login
I can see from the logs, that @pages got the right value, but in my
view, it is nil. It seems that the HTML code is constructed before the
after_action is executed.

Correct. Code in after_action callbacks can examine and mutate the
about-to-be-sent response, but the render has already occurred.

I understood the render() function in that way, that it only sets up
which ERB template is supposed to be used, but actual rendering would
occur only when the action has finished. Did I get this wrong?

When you call render the render happens immediately. If you return
from
an action without rendering or redirecting, the default behavior will
be
executed by ActionPack (rendering the template with the same name as the
action).

–Matt J.

3

Oh, I really got this wrong. So, the HTML is already constructed with
the render call, then the rest of the action is executed!

Thanks a lot.

Ronald