Notes posted by tokland

Anchor option

It’s not documented, but :anchor is an option.

polymorphic_path(commentable, :anchor => 'comments')

will return:

/article/1#comments

About the options argument

The options are not documented, but of course you can use the same options than submit_tag.

Note that all non-documented options are simply passed to the input tag. Amongst other things, this allows you to change the default name attribute (commit):

form.submit 'Cancel', :name => 'cancel'

That’s very handy in forms with multiple submit buttons, this way the controller can easily check in the params which action was submitted.

You must use the yielded object

A warning note (at least for v2.3.4): if you don’t use the yielded format object, you will get a cryptic error like this:

NoMethodError (You have a nil object when you didn't expect it!
The error occurred while evaluating nil.call):
 app/controllers/comments_controller.rb:11:in `create'

So make sure you use it!

Keeping the flash object on multiple redirects

If your controllers are redirecting more than once, the flash contents will be lost. To avoid it, execute flash.keep before each redirection.

Check ActionController::Flash::FlashHash for more handy methods (discard, now, …)

Iterate and join blocks

Following LacKac’s idea, we can write render_join (useful to render a collection with a small chunks of code, where a render :partial + :spacer_template would be overkill):

def render_join(collection, join_string, &block)
  output = collection.collect do |item| 
    capture(item, &block)
  end.join(join_string)
  concat(output, block.binding)
end

An example of use:

<% render_join(@items, '<br />') do |item| %>
   <p>Item title: <%= item.title %></p>
<% end %>