nesting_association_attributes_examples.rb

# Examples of Nesting Associated Attributes
# This is a look at the various ways to set associated attributes through 
# nested parameters. For example, let's say Project has_many :tasks and 
# we want to update the tasks the same time we edit a project. There are 
# several ways this interface could be handled, and here are a few.
#
# For these examples, we're trying to create two new tasks and update an
# existing task (with id 3) through a project.

# Approach 1
# This is the first interface I demonstrated in the 3 Railscasts 
# episodes. Here the tasks are all passed in an array with a hash of 
# attributes for each. Only the existing tasks have an :id attribute.
# http://railscasts.com/episodes/75
# This is also the same interface David Dollar uses in his approach.
# http://groups.google.com/group/rubyonrails-core/browse_thread/thread/4049b4b313fa8be2
{
  :tasks =>
    [
      { :id => 3, :name => 'Foo' },
      { :name => 'Bar' },
      { :name => 'Baz' }
    ]
}

# Approach 2
# This one is from the Advanced Rails Recipes book. The tasks are split 
# up into two different keys: 'existing_task_attributes' which task a 
# hash and 'new_task_attributes' which task an array.
# http://media.pragprog.com/titles/fr_arr/multiple_models_one_form.pdf
{
  :existing_task_attributes =>
    {
      '3' => { :name => 'Foo' }
    },
  :new_task_attributes =>
    [
      { :name => 'Bar' },
      { :name => 'Baz' }
    ]
}

# Approach 3
# From Eloy Duran's nested_params plugin. This takes a single 
# :tasks parameter which is a hash, new records start with "new_" and 
# have a unique identifier (sometimes the object_id).
# http://github.com/alloy/complex-form-examples/tree/alloy-nested_params
{
  :tasks =>
    {
      '3' => { :name => 'Foo' },
      'new_24235' => { :name => 'Bar' },
      'new_35234' => { :name => 'Baz' }
    }
}

# Approach 4
# From Dave Rothlisberger's post on the mailing list. This takes a :tasks 
# hash, each with a unique key usually generated by an incrementing 
# number. Like Approach 1, only the existing tasks have an :id attribute.
# http://groups.google.com/group/rubyonrails-core/browse_thread/thread/3c61e00916c365e5/69ec67ab6380bc53?show_docid=69ec67ab6380bc53
{
  :tasks =>
    {
      '1' => { :id => '3', :name => 'Foo' },
      '2' => { :name => 'Bar' },
      '3' => { :name => 'Baz' }
    }
}

# Approach 5
# From Josh Susser's patch. This is similar to Approach 2, except a hash 
# is used instead of an array for new tasks. The hash key can be anything 
# unique and sortable, such as an incrementing number, the object_id, or 
# the current time.
# http://rails.lighthouseapp.com/projects/8994/tickets/1031
{
  :update_tasks_params =>
    {
      '3' => { :name => 'Foo' }
    }
  :create_tasks_params =>
    {
      '1' => { :name => 'Bar' },
      '2' => { :name => 'Baz' }
    }
}