This article is obsolete. The changes have been rolled into recent versions of Rails such that calling:

1 <%= render :partial => "partial", :object => the_object %>


I was reading the code for the FileColumn, helper and I had a thought. What if we could obviate the need for requiring instance variables for helpers ?

A recent example on the mailing list ? render partial and passing in the object, by Mark Van Holstyn. In the thread, he asks why he can’t do:


1 def edit
2 user</span> = <span class="co">User</span>.find_by_id(<span class="i">1</span>) <span class="no">3</span> render <span class="sy">:partial</span> =&gt; <span class="s"><span class="dl">'</span><span class="k">address</span><span class="dl">'</span></span>, <span class="sy">:object</span> =&gt; <span class="iv">user.address}
4 end

His partial being:


1 ><%= text_area(‘address’, ‘street’) %>

Reading FileColumn helper’s code, and the code in Rails own helpers, the following idiom is used to get a hold of the instance variable:


1 def url_for_file_column(object_name, method, suffix=nil)
2 object = instance_variable_get("@#{object_name.to_s}")
4 end

What if we did it this way instead ?


1 def url_for_file_column(object_name, method, suffix=nil)
2 object = case object_name
3 when String, Symbol
4 instance_variable_get("@#{object_name.to_s}")
5 else
6 object_name
7 end
9 end

Actually, this should all be abstracted away in some kind of helper for helpers. Let me take a moment to prepare a patch. I think this would make things quite a bit easier for partial users.


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I am François Beausoleil, a Ruby on Rails and Scala developer. During the day, I work on Seevibes, a platform to measure social interactions related to TV shows. At night, I am interested many things. Read my biography.

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