Ruby on Rails validation summary

Introduction

I will summarize examples etc. mainly as a memorandum of Rails Tutorial. I would appreciate it if you could point out any mistakes.

What is validation?

Verifying the state of an object before saving it to the database. Verify that the value entered is not invalid. For example, you can prevent empty data from being saved, or you can increase the number of characters.

Basic writing

The basic entry method is as follows.

model

validates :Column name,helper

#If you want to apply to multiple columns
validates :Column name, :Column name, :Column name,helper

Main validation helpers

presence Make sure that the specified attribute is not empty.

model

validates column name, presence: true

model

validates :name, presence: true

#If you want to apply to multiple columns
validates :name, :login, :email, presence: true

length Validate the length of the attribute value. There are many options and you can specify different length limits.

model

validates column name, length: {Limits}

model

  validates :passward, length: { minimum: 5 }        #5 characters or more
  validates :name, length: { maximum: 50 }           #20 characters or less
  validates :passward, length: { in: 3..10  }        #3 to 10 characters
  validates :registration_number, length: { is: 6 }  #Only 6 characters allowed

uniqueness Verify that the value of the attribute is unique and unique.

model

validates :Column name, uniqueness: true

model

validates :name, uniqueness: true

acceptance Verify that the checkbox is selected when the form is submitted. It is used when you need to check "I accept the terms of service".

model

validates :Column name, acceptance: true

model

validates :terms_of_service, acceptance: true

confirmation Validates that the values entered in multiple forms match exactly. It is used to match the values of the email address and the confirmation email address.

model

validates :Column name, confirmation: true

model

validates :email, confirmation: true

numericality Verify that only numbers are used for the attribute.

model

validates column name, numericality: true

model

validates :points, numericality: true

model

#Only integers allowed
validates :age, numericality: { only_integer: true }

Main options

format Verify by testing whether the regular expression given by the with option matches the attribute value.

model

validates :Column name, format: { with:Limits}

model

#Only alphanumeric characters allowed
validates :password, format: { with: /\A[a-zA-Z]+\z/ } 

#Allow only valid email addresses
 VALID_EMAIL_REGEX = /\A[\w+\-.]+@[a-z\d\-]+(\.[a-z\d\-]+)*\.[a-z]+\z/i
 validates :email, format: { with: VALID_EMAIL_REGEX }

Regular expressions like the one above to allow only valid email addresses are based on the table below.

Common options

model

#When writing a message directly
validates column name, presence: { message:“Custom error message”} 

model

validates :name, presence: { message:"Required fields"}

reference

Active Record Validation-Rails Guide v6 \ .0 https://railsguides.jp/active_record_validations.html