Deeply nested attributes

[libc]

Consider the following example:

class User < ActiveRecord::Base
  has_many :phone_numbers

  accepts_nested_attributes_for :phone_numbers
end
    
class PhoneNumber < ActiveRecord::Base
  belongs_to :user
  # This is a bit contrived, because probably it should be many-to-many
  has_many :labels

  accepts_nested_attributes_for :labels
end

class Label < ActiveRecord::Base
  belongs_to :phone_number
end

If you render this on 1 page to edit labels you end up with the following attributes name:

user[phone_numbers_attributes][0][labels_attributes][0][label]

Validation on this field will be generated automatically as:

user[phone_numbers_attributes][][label_attributes][][label]

The current nested attributes javascript looks like /\[(\w+_attributes)\].*\[(\w+)\]$/, which doesn't properly process this nested attributes, with this PR it'll be supported.

There's one use-case that is covered by the current deeply-nested validation, that I do not cover.
user[phone_numbers_attributes][deeply][nested][][attribute] searches for /\[phone_numbers_attributes\].*\[\]\[attribute\]$/ in the validators. So it can match something unintended. I left it as it is right now and only process

I left the initial commit of my colleague @Arie in.

Any feedback welcome.

[coveralls]

Coverage remained the same at 100.0% when pulling 580e024 on Springest:deeply-nested-attributes into 2a24a36 on DavyJonesLocker:master.

[tagliala]

@libc 👏 👏 👏

[tagliala]

@libc please give the master branch a try, I will then release a new version of the gem

[libc]

We're still using 4.2 in production (cherry-picked version of this).

I tried master on our experimental rails-5.0.2-branch and it seems to work fine.