activefx/attribute_fu - Githubissues

= AttributeFu

Creating multi-model forms is amazingly easy with AttributeFu.

= Get It!

$ script/plugin install git://github.com/giraffesoft/attribute_fu.git

= Conventions

attribute_fu requires the fewest keystrokes if you follow certain conventions.

The partial that contains your associated model's form is expected to be called _class_name.template_ext (e.g. the partial for your Task model would be called _task.html.erb)
The DOM element that contains the form for your model should have the CSS class .class_name (e.g. the CSS class for your Task would be .task)
The DOM element that contains all of the rendered forms should have the DOM ID #class_name (e.g. the DOM ID of the container of your Task forms would be #tasks) Note: This is only relevant if using the add_associated_link method.

= Example

In this example, you'll build a form for a Project model, in which a list of associated (has_many) tasks can be edited.

The first thing you need to do is enable attributes on the association.

class Project < ActiveRecord::Base has_many :tasks, :attributes => true end

Instances of Project will now respond to task_attributes, whose format is as follows:

@project.task_attributes = { @project.tasks.first.id => {:title => "A new title for an existing task"}, :new => { "0" => {:title => "A new task"} } }

Any tasks that already exist in that collection, and are not included in the hash, as supplied to task_attributes, will be removed from the association when saved. Most of the time, the form helpers should take care of building that hash for you, though.

== Form Helpers

If you follow certain conventions, rendering your associated model's form elements is incredibly simple. The partial should have the name of the associated element's type, and look like a regular old form partial (no messy fields_for calls, or any nonsense like that).

_task.html.erb

Title <%= f.text_field :title %>

Then, in your parent element's form, call the render_associated_form method on the form builder, with the collection of elements you'd like to render as the only argument.

_form.html.erb

<%= f.render_associated_form(@project.tasks) %>

That call will render the partial named _task.html.erb with each element in the supplied collection of tasks, wrapping the partial in a form builder (fields_for) with all the necessary arguments to produce a hash that will satisfy the task_attributes method.

You may want to add a few blank tasks to the bottom of your form; no need to do that in the controller anymore.

<%= f.render_associated_form(@project.tasks, :new => 3) %>

Since this is Web2.0, no form would be complete without some DHTML add and remove buttons. Fortunately, there are some nifty helpers to create them for us. Simply calling remove_link on the form builder in your _task partial will do the trick.

_task.html.erb

Title <%= f.text_field :title %> <%= f.remove_link "remove" %>

Creating the add button is equally simple. The add_associated_link helper will do all of the heavy lifting for you.

_form.html.erb

<%= f.add_associated_link "Add New Task", @project.tasks.build %>

That's all you have to do to create a multi-model form with attribute_fu!

== Discarding Blank Child Models

If you want to show a bunch of blank child model forms at the bottom of your form, but you only want to save the ones that are filled out, you can use the discard_if option. It accepts either a proc:

class Project < ActiveRecord::Base has_many :tasks, :attributes => true, :discard_if => proc { |task| task.title.blank? } end

...or a symbol...

class Project < ActiveRecord::Base has_many :tasks, :attributes => true, :discard_if => :blank? end

class Task < ActiveRecord::Base def blank? title.blank? end end

Using a symbol allows you to keep code DRYer if you are using that routine in more than one place. Both of those examples, however, would have the same effect.

= Updates

Come join the discussion on the {mailing list}[link:http://groups.google.com/group/attribute_fu]

Updates will be available {here}[http://jamesgolick.com/attribute_fu]

= Running the tests

To run the tests, you need Shoulda, mocha and multi-rails:

$ sudo gem install thoughtbot-shoulda --source http://gems.github.com/ $ sudo gem install mocha multi_rails

== Credits

attribute_fu was created, and is maintained by {James Golick}[http://jamesgolick.com].