Sitecontroller instance variable in custom tag

Ruby Apps Radiant CMS
1

Hi,

I’m trying to figure out how to access the value of an instance variable
that gets setup on SiteController when my extension is activated. I’d
like to use this value in a tag, but I can’ figure out how to access
that variable from the tag.

If I setup a tag that just dumps the page.inspect, like the tag below, I
can see the instance variable in the output, but I just can’t figure out
how to grab it.

tag ‘inspect_page’ do |tag|
tag.globals.page.inspect
end

I’d like to be able to do something like

tag ‘my_instance_variable’ do |tag|
# @my_instance_variable is defined in SiteController on extension
activation
tag.globals.page.my_instance_variable
end

Anyone know how to do this?

Thanks!

2

Dave,

You probably need to explicitly set the instance variable on the page by
overriding process_page. Here’s a sample (untested):

Page.send :attr_accessor, :my_instance_variable

SiteController.class_eval do
def process_page_with_instance_var(page)
page.my_instance_variable = @my_instance_variable
process_page_without_instance_var(page)
end
alias_method_chain :process_page, :instance_var
end

From that, your instance variable would be defined on the global page
(tag.globals.page).

I’ve been looking through the Rails source, but I don’t see anywhere
where the request is given a link back to the controller it’s created
for. You may be out of luck there.

Cheers,

Sean

3

You may want to use Ruby’s instance_variable_get(…) like this:

tag ‘my_instance_variable’ do |tag|
tag.globals.page.instance_variable_get(’@my_instance_variable’)
end

4

I ended up getting it working with the exact method that Sean suggested.
Not bad for untested code, Sean. Thanks!

Todd, it turns out that the instance_variable_get wasn’t necessary
because my_instance_variable was setup with an accessor via:
Page.send :attr_accessor, :my_instance_variable

This made it accessible as:
tag ‘my_instance_variable’ do |tag|
tag.globals.page.my_instance_variable
end

Thanks again!