[PhillyOnRails] jQuery Talk Follow-up

["Randy Schmidt" <randy.schmidt@gmail.com>]

Hi Everybody,

I just wanted to follow with a solution to one of the problems with
using jQuery unobtrusively with rails, and that was RJS. RJS lets you
update multiple items on a page by sending javascript back to the
browser which gets evaluated. RJS only works with Prototype (there may
be plugins that fix this) so you are kind of SOL with other
frameworks. A way around this in Rails >= 2.0 is to use .js.erb
templates which let you write javascript and spit out data from your
app or render partials. You still want to keep most of your js in
externally linked files so what I do is create functions that hide
away the implementation of what I want to do.

contents of index.js.erb:

updateFolloweesStatus(<%= partial 'users/status', :collection =>
current_user.followees %>)
updateCurrentUserDisplayStatus(<%= partial 'users/status', :object =>
current_user %>)
updateCurrentUserInputStatus('<%= current_user.status %>')

The JS:

function updateFolloweesStatus(txt) {
	$('#their_status').html(txt)
}

function updateCurrentUserDisplayStatus(txt) {
	$('#my_status').html(txt)
}

function updateCurrentUserInputStatus(txt) {
	// if the field isn't focused, update it (ie, don't clobber something
that will be changed soon)
	if ($('#user_status.focused').size() == 0) {
		$('#user_status').val(txt)
	}
}

Helpers:

  # from Dan Webb's MinusMOR plugin
  # enhanced with ability to detect partials with template format,
i.e.: _post.html.erb
  def partial(name, options={})
    old_format = self.template_format
    self.template_format = :html
    js render({ :partial => name }.merge(options))
  ensure
    self.template_format = old_format
  end

  def js(data)
    if data.respond_to? :to_json
      data.to_json
    else
      data.inspect.to_json
    end
  end

Hopefully this is helpful and closes the loop on the whole "update
more than one element on the page" issue. Let me know if you have any
questions.

Thanks,
-- 
umlatte llc
Randy Schmidt
randy@umlatte.com
www.umlatte.com
267-334-6833
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