Rails%203%20In%20Action

Using JavaScript
And I follow "Add another file"
no link with title, id or text 'Add another file' found
Before you fix it, however, let’s make the form render only a single asset field by
changing this line in the new action in TicketsController
3.times { @ticket.assets.build }
to this:
@ticket.assets.build
By building only one asset to begin with, you show users that they may upload a file. By
providing the link to Add Another File, you show them that they may upload more
than one if they please. This is the best UI solution because you’re not presenting the
user with fields they may not use.
Now it’s time to make the Add Another File link exist and do something useful!
9.4.2 Introducing jQuery
The Add Another File link, when clicked, triggers an asynchronous call to an action,
which renders a second file field.
For the Add Another File link to perform an asynchronous request when it’s
clicked, you can use the JavaScript framework called jQuery. In earlier versions of
Rails, a JavaScript framework called Prototype came with it, but a large portion of the
community prefers jQuery to Prototype. Developers can choose whether to use Prototype
or jQuery or any other kind of JavaScript framework, but we use jQuery here
because it’s favored in the community. 7
To install jQuery in earlier versions of Rails, you would have had to go to http://
jquery.com, download the latest version of jQuery, put it in your public/javascripts, and
then include it in your application layout. Next, you would have had to install the
jquery-rails gem. It was quite a lot of work for something that should have been
simple!
With Rails 3.1, you don’t need to download jQuery from the website or alter the
default application in any way. With jquery-rails in the application’s Gemfile, you
are already set up.
Next, tell your application to include the JavaScript files from this gem if Rails hasn’t
done it already. Currently, you have this line in your app/views/layouts/application
.html.erb file:
It generates HTML like this:
7 Our choice totally has nothing to do with the fact that one of the authors is on the jQuery Core Team! We
promise!
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