calling a partial from within a model / model's method?

Hey everyone,

I have a model I extended w/STI to allow me to write little widgets or modules for my web-app … that part’s working well. However, I’m getting to the point where, depending on the model’s type/class I would like to render a partial so that each type has it’s own look/feel/content.

I found this : … and it works pretty well. I had all my models calling their own partials, but, helper functions like link_to and url_for, etc, will not work. As mentioned in the comments to that blog post

Love the tip, it breaks though when your view code uses helper
, to do this, I stole from Rails internal private method,

template_instance =
template_instance.extend ApplicationController.master_helper_module
content = template_instance.render(:partial => self.view_path(self.profile) + ‘/show’, :locals => {:item => self})

I tried this, but am still not having any luck.

Has anyone tried this sort of thing before? I’m trying to do a simple link_to for a nested resource (which works fine within the context of a straight view, but I get this when calling the partial from my model(s)

You have a nil object when you didn't expect it!
The error occurred while evaluating nil.url_for

Thanks everyone!

  • Joel

Hi Joel. I'm not quite sure why you want to render partials or
templates from within your model(s). I'm sure you have some good
reasons, but sometimes there're ways of accomplishing what you want
without violating the "rules" of the MVC design pattern.

Would you mind explaining in more detail why your model(s) need to
render partials and/or templates?


Hey Nick!

First - thanks for the reply.

Second - the reason why I’m trying to do this is to allow whatever type of widget model I’m creating to render its own particular partial, in the context of the “area” a user will place it - header, footer, sidebar, etc. I thought that calling a helper to weed out the objects for a particular “area” and then letting the model call its partial on its own, would be the easier way to do it, despite the normal MVC rules. I know it’s against the rules - so I’m wondering if there’s an easier way?

Any input would be appreciated! :slight_smile:


  • Joel

Hi Joel. Why not create a helper method that determines which partial should be rendered? For example:


Weeks later I finally got around to figuring out how to best tackle this and your suggestion was right on the money. I didn’t want to let this lie without mentioning that the best bet started with that nugget from the pastie link. Thanks Nick :slight_smile:

  • Joel

I'm glad to hear it helped! Good luck, mate.