Has Many With Params Methods

To help write code with “Fat model, skinny controllers”, it is useful to hide child attributes from Views and Controllers behind parent proxy methods.

i.e. Imagine the simple relation of

class Dog < ActiveRecord::Base
  belongs_to :owner
end

class Owner < ActiveRecord::Base
  has_many :dogs
end

We can provide fields to insert / update multiple Dogs in a single Owner HTML form:

<input name="owner[name]" type="text" />
<input name="ownerdogs_params[name]" type="text" />
<input name="ownerdogs_params[breed]" type="text" />
<input name="ownerdogs_params[name]" type="text" />
<input name="ownerdogs_params[breed]" type="text" />

Our controller action can continue to be simple (the concept of Dog is hidden).. in fact it can remain unmodified from the vanilla Owner scaffold code:

@owner = Owner.new params[:owner] 
@owner.save

This is because, this plugin provides Owner a dogs_params=() method that kicks in when controller does aka,

@owner.name = params:owner @owner.dogs_params = params:owner

1. note: params:owner is a hash that looks like
3. {
4. “0” => { “name” => “Snoopy”, “breed” => “Beagle” },
5. “1” => { “name” => “Lassie”, “breed” => “Collie” },
6. }

All database queries will happen when @owner is saved and not when @owner.dogs_params is called.

Example

For a more comprehensive example, see test/has_many_with_params_methods_test.rb under “test_this_plugin”

Test

Warning: 3 tables (owners, pets, animals) will be created and dropped from your TEST database.

Just execute this command: PLUGIN=has_many_with_params_methods rake test:plugins

Copyright© 2007 Chew Choon Keat, released under the MIT license

NOTE: This description has been extracted from the Plugin README and so the formatting may need updating to make browser friendly