Rails Validations - Overview

i keep forgetting that, so i post it here for me and everyone else.

Here is the list of validations which you can perform on user input:

validates_presence_of:

Following check that last_name and first_name should be filled and should not be NOLL.

validates_presence_of :firstname, :lastname

validates_length_of:

Following example shows various validations on a single filed. These validations can be performed separately.

validates_length_of :password, :minimum => 8 # more than 8 characters :maximum => 16 # shorter than 16 characters :in => 8..16 # between 8 and 16 characters :too_short => 'way too short' :too_long => 'way to long'

validates_acceptance_of:

Following will accept only 'Y' value for option field.

validates_acceptance_of :option :accept => 'Y'

validates_confirmation_of:

The fields password and password_confirmation must match and will be used as follows:

validates_confirmation_of :password

validates_uniqueness_of:

Following puts a condition for user_name to be unique.

validates_uniqueness_of :user_name

validates_format_of:

Following validates a that given email ID is in a valid format. This shows how you can use regualr expression to validatea filed.

validates_format_of :email :with => /^(+)@((?:[-a-z0-9]+\.)+[a-z]{2,})$/i

validates_numericality_of:

This validates that given field is numeric.

validates_numericality_of :value :only_integer => true :allow_nil => true

validates_inclusion_of:

Following checks that passed value is an enumeration and falls in the given range.

validates_inclusion_of :gender, :in => %w( m, f )

validates_exclusion_of:

Following checks that given values does not fall in the given range.

validates_exclusion_of :age :in => 13..19

validates_inclusion_of:

Following checks that given values should fall in the given range. This is opposite to validates_exclusion_of.

validates_inclusion_of :age :in => 13..19

validates_associated:

This validates that the associated object is valid.

Options for all Validations:

You can use following options alongwith all the validations.

• :message => 'my own errormessage' Use this to print a custom error message in case of validation fails.




• :on => :create or :update This will be used in such cases where you want to perform validation only when record is being created or updated. So if you use :create then this validation work only when there is a create opration on database.

Check the following link for more detail on Validations.