Rails 5 Create module and class level variables
Rails already provides methods for creating class level and module level variables in the form of cattr** and mattr** suite of methods. In Rails 5, we can go a step further and create thread specific class or module level variables. Here is an example which demonstrates an example on how to use it. 1 2module CurrentScope 3 thread_mattr_accessor :user_permissions 4end 5 6class ApplicationController
Errors can be indexed with nested attributes in Rails 5
We use accepts_nested_attributes_for when we want a single form to cater to multiple models. By using this we can easily provide attributes for associated models. In Rails 4.x, if a validation fails for one or more of the associated models, then it is not possible to figure out from error message, which of the associated model object is the error related to. 1 2class Product < ApplicationRecord 3h
Rails 5 adds OR support in Active Record
Rails 5 has added OR method to Active Relation for generating queries with OR clause. 1 2>> Post.where(id: 1).or(Post.where(title: 'Learn Rails')) 3 SELECT "posts".* FROM "posts" WHERE ("posts"."id" = ? OR "posts"."title" = ?) [["id", 1], ["title", "Learn Rails"]] 4 5=> <ActiveRecord::Relation [#<Post id: 1, title: 'Rails'>]> 6 Copy This returns ActiveRecord::Relation object, which is logical unio
Rails 5 supports bi-directional destroy dependency
In Rails 4.x, it is not possible to have destroy dependency on both sides of a bi-directional association between the two models as it would result in an infinite callback loop causing SystemStackError: stack level too deep. 1 2class User < ActiveRecord::Base 3 has_one :profile, dependent: :destroy 4end 5 6class Profile < ActiveRecord::Base 7 belongs_to :user, dependent: :destroy 8end 9 Copy 1 2>>
Rails 5 Updating a record without updating timestamps
In Rails 4.x, when we save an ActiveRecord object then Rails automatically updates fields updated_at or updated_on. 1 2>> user = User.new(name: 'John', email: 'john@example.com') 3>> user.save 4 INSERT INTO "users" ("name", "created_at", "updated_at", "email") VALUES (?, ?, ?, ?) [["name", "John"], ["created_at", 2016-03-16 09:12:44 UTC], ["updated_at", 2016-03-16 09:12:44 UTC], ["email", "john@ex
has_secure_token for unique random token in Rails 5
We sometimes need unique and random tokens in our web apps. Here is how we typically build it. 1class User < ActiveRecord::Base 2 3 before_create :set_access_token 4 5 private 6 7 def set_access_token 8 self.access_token = generate_token 9 end 10 11 def generate_token 12 loop do 13 token = SecureRandom.hex(10) 14 break token unless User.where(access_token: token).exists? 15 end 16 end 17endCopy
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Rails 5 makes sql statements even more colorful
