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* ActiveRecord Validations Cheatsheet

Comprehensive but concise details of Rails' built-in class validation helper methods from validates_acceptance_of through to validates_uniqueness_of, along with details of how to roll your own low-level validations along with examples...

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Common options

:message

a custom error message

:on

specifies when this validation is active (default is :save, other options :create, :update)

:allow_nil

skip validation if attribute is nil (default is false). Notice that for fixnum and float columns empty strings are converted to nil

:allow_blank

if set to true, skips this validation if the attribute is blank (default is false)

:if

specifies a method, proc or "string" to call to determine if the validation should occur (e.g. :if => :allow_validation, or :if => Proc.new { |user| user.signup_step > 2 }). The method, proc or "string" should return or evaluate to a true or false value.

:unless

specifies a method, proc or "string" to call to determine if the validation should not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }). The method, proc or "string" should return or evaluate to a true or false value.

 

 

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