This article will discuss a concept known as Custom Validations in Rails Active Record. There are two types of custom validations; Custom Validators and Custom Methods.
Here’s a bit of setup before tackling each type individually:
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rails new custom-validations
rails generate model Article title body:text
rails db:create db:migrate
Start with Custom Validator. In app/models/concerns, create a file named title_validator.rb and put the following content in it:
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# app/models/concerns/title_validator.rb
class TitleValidator < ActiveModel::Validator
def validate(record)
unless record.title.include? 'Rails'
record.errors[:title] << 'We only publish articles written on Rails!'
end
end
end
Include it in the app/models/article.rb.
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# app/models/article.rb
class Article < ApplicationRecord
include ActiveModel::Validations
validates_with TitleValidator
end
Now test the validator.
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rails console
article = Article.create(title: "Uploading Images in Laravel", body: "This aticle will discuss how to upload images in Laravel.....")
article.valid?
=> false
article.errors
=> #<ActiveModel::Errors:0x00007fe54e236b40 @base=#<Article id: nil, title: "Uploading Images in Laravel", body: "This aticle will discuss how to upload images in L...", created_at: nil, updated_at: nil>, @messages={:title=>["We only publish articles written on Rails!"]}, @details={}>
article = Article.create(title: "Uploading Images in Rails", body: "This article will discuss how to upload images in Rails.....")
article.valid?
=> true
Now onto Custom Methods.
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class Article < ApplicationRecord
validate :title_include_rails
def title_include_rails
unless title.include? 'Rails'
errors.add(:title, 'We only publish articles written on Rails!')
end
end
end
Test the implementation:
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article = Article.create(title: "Uploading Images in Laravel", body: "This aticle will discuss how to upload images in Laravel.....")
article.valid?
=> false
article.errors
=> #<ActiveModel::Errors:0x00007fe54aaf0960 @base=#<Article id: nil, title: "Uploading Images in Laravel", body: "This aticle will discuss how to upload images in L...", created_at: nil, updated_at: nil>, @messages={:title=>["We only publish articles written on Rails!"]}, @details={:title=>[{:error=>"We only publish articles written on Rails!"}]}>
article = Article.create(title: "Uploading Images in Rails", body: "This aticle will discuss how to upload images in Rails.....")
article.valid?
=> true
Now you’ve learned how to implement custom validations in Ruby on Rails. Happy validating!