Ruby on Rails - validates format of an attribute in ruby on rails- ruby on rails tutorial - rails guides - rails tutorial - ruby rails

We can add our own validations adding new classes inheriting from ActiveModel::Validator or from ActiveModel::EachValidator.
Both methods are similar but they work in a slightly different ways:

ActiveModel::Validator and validates_with

Implement the validate method which takes a record as an argument and performs the validation on it. Then use validates_with with the class on the model.

# app/validators/starts_with_a_validator.rb
class StartsWithAValidator < ActiveModel::Validator
  def validate(record)
    unless record.name.starts_with? 'A'
      record.errors[:name] << 'Need a name starting with A please!'
    end
  end
end
 
class Person < ApplicationRecord
  validates_with StartsWithAValidator
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ActiveModel::EachValidator and validate

If we prefer to use our new validator using the common validate method on a single param, create a class inheriting from ActiveModel::EachValidator and implement the validate_each method which takes three arguments: record, attribute, and value:

class EmailValidator < ActiveModel::EachValidator
  def validate_each(record, attribute, value)
    unless value =~ /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\z/i
      record.errors[attribute] << (options[:message] || 'is not an email')
    end
  end
end
 
class Person < ApplicationRecord
  validates :email, presence: true, email: true
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Validate that an attribute's value matches a regular expression using format and the with option.

class User < ApplicationRecord
  validates :name, format: { with: /\A\w{6,10}\z/ }
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We can also define a constant and set its value to a regular expression and pass it to the with: option. This might be more convenient for really complex regular expressions

PHONE_REGEX = /\A\(\d{3}\)\d{3}-\d{4}\z/
validates :phone, format: { with: PHONE_REGEX }Clicking "Copy Code" button will copy the code into the clipboard - memory. Please paste(Ctrl+V) it in your destination. The code will get pasted. Happy coding from Wikitechy - ruby on rails tutorial - rails guides - ruby rails - rubyonrails - learn ruby on rails - team

Default error message is is invalid.
This can be changed with the :message option.

alidates :bio, format: { with: /\A\D+\z/, message: "Numbers are not allowed" }Clicking "Copy Code" button will copy the code into the clipboard - memory. Please paste(Ctrl+V) it in your destination. The code will get pasted. Happy coding from Wikitechy - ruby on rails tutorial - rails guides - ruby rails - rubyonrails - learn ruby on rails - team