Using after_filter to control rendering on actions

Rails
1

I have a common failure page that I may need to render to upon failing
some test that occurs in an after_filter method.

I’d like to use the after_filter to take over the control of the
rendering, like so:

def test_for_validity
some_boolean = my_test
return render(:action => ‘disqualified’) unless some_boolean
@success_controller ||= controller_name
@success_action ||= action_name
return render(:controller => @success_controller, :action =>
@success_action)
end

In my action, if I do nothing unusual, then I expect to render to the
regular place. If I override @success_controller and/or
@success_action, then my action code can set up the success target.

Unfortunately, when I try to do this, I get a DoubleRenderError, which I
am sure is because the default render is already done in my action
before I attempt to do either render in the after filter.

Can this be done, or do I have to resign myself to only setting the
target in the after_filter, and then doing the rendering in the action
method itself?

Thanks,
Wes

2

Can I just modify the response somehow in my after filter perhaps?

WG

3

It looks like theoretically, at least, I could manipulate the response
body directly, which I think implies that I would be rewriting render to
a degree.

Of course, it’s all a non-issue unless I could override the default
rendering behavior.

WG

4

As it turns out, this is a non-issue.

But one way that you could get similar behavior would be to use
redirect_to in a before filter to respond to the test, whatever it is.

But in order to do this, you would have to always redirect_to every
action that the before filter was applied to, in order to get the before
filter to run.

Bottom line: It would be nice to have the ability to control/impact
rendering for an action outside of the action method itself.

Wes

5

In AWDWR v.1, p. 326, there’s an example of directly manipulating the
response body.

Has anyone else done this and can you vouch for the safety of the
process?

I would have to process whichever template content that I wanted to
return and then put that result of that rendering into the response
body, right?

Thanks,
Wes

6

Right, but I can’t control what is rendered into HTML/XML whatever
easily.

7

You can definitely modify the response in an after_filter: we have a
bunch of actions that produce xml, and an after filter that runs the xml
through an xslt filter (and the user only ever sees the resulting html)

Fred