Validation

There must be something twirling inside your mind after seeing validations in ruby, validation

are basically used to check whether you are sending right parameters or not. i will explain you

by brief code

class School < ActiveRecord::Base
  validates :name, presence: true
end
 
School.create(name: "Delhi").valid? # => true
School.create(name: nil).valid? # => false

As you go through above code you have seen that in a class School we validates name, School will not validate it without name attribute, it is necessary to pass name attribute in School class, it will not permit second School as it has give nil as name attribute.

Use of Validation

we use validation to permit exactly what attribute we want to send in database,As you have seen in many websites login page we cannot enter name attribute in email  textbox, only valid email address will be send to database otherwise it would be cumbersome for end user.

To Check Whether Validation is valid or not

if you want to check whether your validation object is valid or not we well do like this

class School < ActiveRecord::Base
  validates :name, presence: true
end
 
School.create(name: "Delhi").valid? # => true
School.create(name: nil).valid? # => false

valid? will check whether the given attribute is valid or not

Here are list of validation we can used in input text

1.Validates length of passed string

We can also check whether the length of passed string is more than what we have validated.

class School < Active Record: :Base
validates length_of :name, maximum=>30

validates_acceptance_of

This will accept only 'Y' value for new field.

 validates_acceptance_of :new            
                        :accept => 'Y' 

validates_confirmation_of this will confirm whether password field is matching with password_confirmation

 validates_confirmation_of :password 

validates_numericality_of This  ensures the numericality of field

 

    validates_numericality_of :value

     :only_integer=> true

     :allow=> nil