如何在 Rails 中获取博客中的所有消息

Question

I am trying to practice my syntax with rails.

I have 3 tables which is:

Blog:

class Blog < ActiveRecord::Base
# Relationships
has_many :owners
has_many :posts
has_many :users, through: :owners
has_many :users_posts, through: :posts, source: :user

# Validations
validates :name, :description, presence: true
end

Post:

class Post < ActiveRecord::Base
  # Relationships
  belongs_to :blog
  belongs_to :user
  has_many :messages, dependent: :destroy

  # Validation
  validates :title, :content, presence: true, length: { minimum: 3 }

  # Update Method
  after_update :updated

  def updated
      puts "Got Updated"
  end
end

And Message:

class Message < ActiveRecord::Base
  belongs_to :post
  belongs_to :user
  # Validation
  validates :author, :message, presence: true, length: { minimum: 3 }
end

I'm trying with the terminal by rails console

and I'm trying to get all the messages from the blog id 5 by this command

Blog.find(5).posts.messages it's not working but when I tried Blog.find(5).posts.first.messages => It showed me the message. So is there anyway I can get all the message from blog 5 in 1 command?

Answer 1

Two ways:

1) with an association. Add to blog

has_many :messages, through: :posts

and then

messages = Blog.find(5).messages

2) with a query, without a specific association for it

messages = Message.joins(post: :blog).where(blogs: { id: 5 })

Answer 2

Add 1 more association to Blog class has_many:messages, through: :posts and then you'll be able to access Blog.find(5).messages