Rails update_attributes without save?

I believe what you are looking for is assign_attributes.

It's basically the same as update_attributes but it doesn't save the record:

class User < ActiveRecord::Base  attr_accessible :name  attr_accessible :name, :is_admin, :as => :adminenduser = User.newuser.assign_attributes({ :name => 'Josh', :is_admin => true }) # Raises an ActiveModel::MassAssignmentSecurity::Erroruser.assign_attributes({ :name => 'Bob'})user.name        # => "Bob"user.is_admin?   # => falseuser.new_record? # => true

You can use assign_attributes or attributes= (they're the same)

Update methods cheat sheet (for Rails 6):

• update = assign_attributes + save
• attributes= = alias of assign_attributes
• update_attributes = deprecated, alias of update

Source:
https://github.com/rails/rails/blob/master/activerecord/lib/active_record/persistence.rb
https://github.com/rails/rails/blob/master/activerecord/lib/active_record/attribute_assignment.rb

Another cheat sheet:
http://www.davidverhasselt.com/set-attributes-in-activerecord/#cheat-sheet

You can use the 'attributes' method:

@car.attributes = {:model => 'Sierra', :years => '1990', :looks => 'Sexy'}

Source: http://api.rubyonrails.org/classes/ActiveRecord/Base.html

attributes=(new_attributes, guard_protected_attributes = true)Allows you to set all the attributes at once by passing in a hash with keys matching the attribute names (which again matches the column names).

If guard_protected_attributes is true (the default), then sensitive attributes can be protected from this form of mass-assignment by using the attr_protected macro. Or you can alternatively specify which attributes can be accessed with the attr_accessible macro. Then all the attributes not included in that won’t be allowed to be mass-assigned.

class User < ActiveRecord::Base  attr_protected :is_adminenduser = User.newuser.attributes = { :username => 'Phusion', :is_admin => true }user.username   # => "Phusion"user.is_admin?  # => falseuser.send(:attributes=, { :username => 'Phusion', :is_admin => true }, false)user.is_admin?  # => true