Active Records implement validation by overwriting Base#validate (or the variations, validate_on_create and validate_on_update). Each of these methods can inspect the state of the object, which usually means ensuring that a number of attributes have a certain value (such as not empty, within a given range, matching a certain regular expression).
Example:
class Person < ActiveRecord::Base protected def validate errors.add_on_empty %w( first_name last_name ) errors.add("phone_number", "has invalid format") unless phone_number =~ /[0-9]*/ end def validate_on_create # is only run the first time a new object is saved unless valid_discount?(membership_discount) errors.add("membership_discount", "has expired") end end def validate_on_update errors.add_to_base("No changes have occurred") if unchanged_attributes? end end person = Person.new("first_name" => "David", "phone_number" => "what?") person.save # => false (and doesn't do the save) person.errors.empty? # => false person.errors.count # => 2 person.errors.on "last_name" # => "can't be empty" person.errors.on "phone_number" # => "has invalid format" person.errors.each_full { |msg| puts msg } # => "Last name can't be empty\n" + "Phone number has invalid format" person.attributes = { "last_name" => "Heinemeier", "phone_number" => "555-555" } person.save # => true (and person is now saved in the database)
An Errors object is automatically created for every Active Record.
Please do have a look at ActiveRecord::Validations::ClassMethods for a higher level of validations.
Returns the Errors object that holds all information about attribute error messages.
# File lib/big_record/validations.rb, line 784 def errors @errors ||= Errors.new(self) end
The validation process on save can be skipped by passing false. The regular Base#save method is replaced with this when the validations module is mixed in, which it is by default.
# File lib/big_record/validations.rb, line 739 def save_with_validation(perform_validation = true) if perform_validation && valid? || !perform_validation save_without_validation else false end end
Attempts to save the record just like Base#save but will raise a RecordInvalid exception instead of returning false if the record is not valid.
# File lib/big_record/validations.rb, line 749 def save_with_validation! if valid? save_without_validation! else raise RecordInvalid.new(self) end end
Updates a single attribute and saves the record without going through the normal validation procedure. This is especially useful for boolean flags on existing records. The regular update_attribute method in Base is replaced with this when the validations module is mixed in, which it is by default.
# File lib/big_record/validations.rb, line 760 def update_attribute_with_validation_skipping(name, value) send(name.to_s + '=', value) save(false) end
Runs validate and validate_on_create or validate_on_update and returns true if no errors were added otherwise false.
# File lib/big_record/validations.rb, line 766 def valid? errors.clear run_validations(:validate) validate if new_record? run_validations(:validate_on_create) validate_on_create else run_validations(:validate_on_update) validate_on_update end errors.empty? end
Overwrite this method for validation checks on all saves and use Errors.add(field, msg) for invalid attributes.
# File lib/big_record/validations.rb, line 790 def validate #:doc: end
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