validate,valid?

http://api.rubyonrails.org/classes/ActiveRecord/Validations.html#M001627

<br /> class Person < ActiveRecord::Base<br /> protected<br /> def validate<br /> errors.add_on_empty %w( first_name last_name )<br /> errors.add("phone_number", "has invalid format") unless phone_number =~ /[0-9]*/<br /> end<br /><br /> def validate_on_create # is only run the first time a new object is saved<br /> unless valid_discount?(membership_discount)<br /> errors.add("membership_discount", "has expired")<br /> end<br /> end<br /><br /> def validate_on_update<br /> errors.add_to_base("No changes have occurred") if unchanged_attributes?<br /> end<br /> end<br /><br /> person = Person.new("first_name" => "David", "phone_number" => "what?")<br /> person.save # => false (and doesn't do the save)<br /> person.errors.empty? # => false<br /> person.errors.count # => 2<br /> person.errors.on "last_name" # => "can't be empty"<br /> person.errors.on "phone_number" # => "has invalid format"<br /> person.errors.each_full { |msg| puts msg }<br /> # => "Last name can't be empty\n" +<br /> "Phone number has invalid format"<br /><br /> person.attributes = { "last_name" => "Heinemeier", "phone_number" => "555-555" }<br /> person.save # => true (and person is now saved in the database)<br />