render :nothing deprecated?

I get a warning "render :nothing deprecated, use render :file
instead"... but I cannot find any info on how to use render :file to
render nothing. It's also not mentioned on the deprecated items web
page, it this warning a bug?

render :nothing => true should still work and not be deprecated.


To add to what Fred said, you may be wondering why you need

   :nothing => true

instead of just


The reason is that you used to be able to write:

   render "path/to/some_file.rhtml"

which was equivalent to

   render_file "path/to/some_file.rhtml"

The Rails guys decided to get rid of all the render_xxx methods and
just have a single render method that takes a hash of options:

   render :action => 'blah'
   render :file => 'blech'
   render :inline => '<%= foo %>'

In order to provide backward compatibility, render looks at its
argument. If it's a Hash, it's treated as the new-style way of doing
things. Otherwise, it's assume to be the old render "some_file"
method, so the argument gets passed along to render_file, and a
deprecation warning is issued (since this will go away completely in
Rails 2.0).

So, with all that background,

   render :nothing

actually is transformed into

   render :file => :nothing

which isn't what you intended.

By writing

   render :nothing => true

render receives a Hash as it's argument (because of the => operator),
so you get nothing rendered.

Ruby has an interesting feature in method calls, where a Hash literal
and the *end* of a parameter list does not need to be enclosed in
braces. So

  render :nothing => true

is really the same as

  render({:nothing => true})

It's a nice feature, because it cuts down on the "line noise" so
common with Perl e.g., but you need to be aware of it because it can
be misleading. For example:

   update_attribute :foo, "Bar" # two arguments passed
   update_attributes :foo => "Bar" # *one* argument (a Hash) passed

Ah, thanks for the reply both. I noticed it's my own fault (as usual),
I used a string instead of a symbol but the warning message threw me

DEPRECATION WARNING: You called render('nothing'), which is a
deprecated API call. Instead you use render :file => nothing.