[feature] Support for nested attributes

[Morpheu5]

Follow up from https://github.com/kla/php-activerecord/issues/issue/111, see also http://www.phpactiverecord.org/boards/1/topics/309

It would be useful to be able to build forms for nested attributes, and using the posted array to update the model and its associated models all at once.

For example, consider an Invoice model that has many Items. The form would send back something like

invoice[id] = 42
invoice[description] = Lorem ipsum dolor
invoice[paid] = 1
invoice[items_attributes][0][description] = First item
invoice[items_attributes][0][price] = 100
invoice[items_attributes][1][description] = Second item
invoice[items_attributes][1][price] = 250

and so on. Then, in Rails, you'd do something like

def update
    invoice = Invoice.find(params[:id]) # the id comes from the URL, not from the form
    invoice.update_attributes(params[:invoice]) # and this is the array that comes from the form
end

and the ActiveRecord::Base component (educated guess) takes care of updating the model's attributes and any relevant associated object.

[miklschmidt]

Actually i am currently working on this, in a seperate class layer above phpactiverecord and a function called from_post(). It's already semi functional, if my boss allows it, i'll modify it to fit this description and submit a pull request.

[miklschmidt]

#187 There we are :)