AttrAccessibleBlock 0.3.0

If you need same functionallity for the Rails 2.3 or Rails 3.0, then use v0.2.2, it's fully tested and ready for this oldies. New version is total rewrite of the previous plugin, but API is the same.

This is an ActiveModel plugin with possibility to define block inside the attr_accessible class method.

Because of block, it's possible to define accessibles for instances, not just for the class level.

It's also still possible to define class level accessibles, so an old attr_accessible :name will work.

Main features:

Possibility to add an accessible attributes based on current record state (eg. record.new_record?)
Possibility to add additional variables and use it in the block (eg. user.role) ActiveRecord::AttrAccessibleBlock.add_variable(:user) { User.current || User.new }
Possibility to add permanently total accessibility in defined condition (eg.user.admin?) ActiveRecord::AttrAccessibleBlock.always_accessible { user.admin? }

Also it's possible to check directly is attribute mass-assignable or no using attr_accessible? instance method.

See an examples to understand the conception.

Installation

gem install attr_accessible_block

Examples

How many times you had code like that:

class User < ActiveRecord::Base
  attr_accessible :password, :password_confirmation

  # ...
end

And in controller:

def create
  user = User.new(params[:user])
  user.email = params[:user][:email]
  user.save

  # ...
end

Now it's possible to do it easier:

class User < ActiveRecord::Base
  attr_accessible do
    add [:password, :password_confirmation]
    add :email if record.new_record?
  end
end

And creation of the user now can be written more DRYer

user = User.create(params[:user])

And on user update changing of email will be rejected because of new_record? method.

Sometimes you may need to check is attribute of model assignable or no (this method mostly interesting when doing form inputs). You can do it with using attr_accessible? method:

user.attr_accessible?(:email) # returns false
user.attr_accessible?(:password) # returns true

How do I add something similar to record, for example I want to check current users role?

Easy, with sentient_user gem and add the code to the config/initializers/plugins.rb file:

ActiveModel::MassAssignmentSecurity::WhiteListBlock.add_variable(:user) { User.current || User.new }

Now user method available, you can check:

attr_accessible do
  add [:password, :password_confirmation]
  add :email if record.new_record? || user.manager?
  add [:some_secret_fields, :another] if user.manager?
end

What if I want to provide an total accessibility for the admin user?

Just add this code to the config/initializers/plugins.rb file:

ActiveModel::MassAssignmentSecurity::WhiteListBlock.always_accessible { user.admin? }

NOTICE: when using attr_accessible as a block, then no second parameter is available for the attributes= method (guard_protected_attributes = true). Instead use power of blocks! Also do not use attr_protected, because it's bad :)

Should be STI compatible, but haven't tested yet. Need's feedback on this feature. Feel free to contact with me if something goes wrong.

For more answers on your questions you can look into tests and source code.

Used on http://tenerife.by