• If I used psql to create these new tables as,

CREATE TABLE authors (
  id SERIAL PRIMARY KEY,
  name VARCHAR(255) NOT NULL
);

CREATE TABLE author_details (
  id SERIAL PRIMARY KEY,
  bio TEXT,
  email VARCHAR(255),
  website VARCHAR(255),
  profile_picture BYTEA,
  author_id INTEGER UNIQUE REFERENCES authors(id) ON DELETE CASCADE
  /* UNIQUE to enforce the one-to-one relationship between authors and author_details */
);

CREATE TABLE posts (
  id SERIAL PRIMARY KEY,
  title VARCHAR(255) NOT NULL,
  tag VARCHAR(255)[],
  body TEXT NOT NULL,
  author_id INTEGER REFERENCES authors(id) ON DELETE CASCADE
  /* one-to-many relationship between authors and posts */
);

Help me to write rais db:migrate migration files, please.

Sure! Here are the migration files you can use to generate the same database schema that you created using psql:

create_authors.rb migration file to create the authors table:

class CreateAuthors < ActiveRecord::Migration[6.1]
  def change
    create_table :authors do |t|
      t.string :name, null: false

      t.timestamps
    end
  end
end

create_author_details.rb migration file to create the author_details table:

class CreateAuthorDetails < ActiveRecord::Migration[6.1]
  def change
    create_table :author_details do |t|
      t.text :bio
      t.string :email
      t.string :website
      t.binary :profile_picture
      t.references :author, foreign_key: true, unique: true, on_delete: :cascade

      t.timestamps
    end
  end
end

create_posts.rb migration file to create the posts table:

class CreatePosts < ActiveRecord::Migration[6.1]
  def change
    create_table :posts do |t|
      t.string :title, null: false
      t.string :tag, array: true
      t.text :body, null: false
      t.references :author, foreign_key: true, null: false, on_delete: :cascade

      t.timestamps
    end
  end
end

In these migration files, we are using the create_table method to define the structure of the database tables. We are also using the references method to define the foreign key relationships between the author_details and posts tables and the authors table. The foreign_key and on_delete options specify how to handle cascading deletes when an author is deleted.

To run these migrations, use the following command in your terminal:

$ rails db:migrate

This will execute all three migration files and create the authors, author_details, and posts tables in your PostgreSQL database.

• Then please help me with rails db:seed files
  • Sure, here's an example seeds.rb file that you can use to populate your database with some sample data:

# Seed authors
authors = [
  { name: 'John Doe' },
  { name: 'Jane Smith' },
  { name: 'Bob Johnson' }
]

authors.each do |author|
  Author.create!(author)
end

# Seed author details
author_details = [
  { bio: 'John is a freelance writer who loves to travel.', email: 'john.doe@example.com', website: 'https://johndoe.com', author_id: 1 },
  { bio: 'Jane is a software engineer who enjoys hiking.', email: 'jane.smith@example.com', website: 'https://janesmith.com', author_id: 2 },
  { bio: 'Bob is a teacher who plays guitar in his free time.', email: 'bob.johnson@example.com', website: 'https://bobjohnson.com', author_id: 3 }
]

author_details.each do |details|
  AuthorDetail.create!(details)
end

# Seed posts
posts = [
  { title: 'My trip to Paris', tag: ['travel', 'Europe'], body: 'I recently visited Paris and it was amazing!', author_id: 1 },
  { title: 'The benefits of hiking', tag: ['hiking', 'outdoors'], body: 'Hiking is a great way to stay active and improve your mental health.', author_id: 2 },
  { title: 'Learning guitar as an adult', tag: ['music', 'hobbies'], body: 'It\'s never too late to learn a new skill like playing guitar!', author_id: 3 },
  { title: 'Why I love sushi', tag: ['food', 'Japan'], body: 'Sushi is one of my favorite foods and I love trying new sushi restaurants.', author_id: 1 },
  { title: 'Tips for traveling on a budget', tag: ['travel', 'budget'], body: 'Traveling doesn\'t have to be expensive. Here are some tips for traveling on a budget.', author_id: 2 },
  { title: 'Teaching in the age of technology', tag: ['education', 'technology'], body: 'Technology has changed the way we teach and learn.', author_id: 3 }
]

posts.each do |post|
  Post.create!(post)
end

In this seeds.rb file, we are first defining some sample data for the authors, author_details, and posts tables. Then, we are using the create! method to create records in the database for each of these models.

To run the seed file, use the following command in your terminal:

$ rails db:seed

This will populate the authors, author_details, and posts tables in your PostgreSQL database with the sample data.

• Then, help me to create CRUD routes of entering authors, author_details and posts.
  • sure! Here's an example of how you could define the CRUD routes for the authors, author_details, and posts models in your config/routes.rb file:

Rails.application.routes.draw do
  # Routes for Authors
  resources :authors do
    resources :author_details, only: [:new, :create, :edit, :update]
    resources :posts, only: [:new, :create, :edit, :update, :destroy]
  end
  
  # Routes for Author Details
  resources :author_details, only: [:show]
  
  # Routes for Posts
  resources :posts, only: [:show]
end

In this example, we're using nested resources to define the routes for the authors, author_details, and posts models. This means that each author can have multiple author details and multiple posts, and we can access these records through the author's ID.

The resources method generates seven standard RESTful routes for each resource: index, show, new, create, edit, update, and destroy. In this example, we're only defining specific actions for each resource:

• For authors, we're defining routes for creating, updating, and deleting posts, as well as creating and updating author_details.
• For author_details, we're only defining a show route, since we don't want to allow editing or deleting author details directly.
• For posts, we're only defining a show route, since we don't want to allow editing or deleting posts directly.

Of course, you can customize these routes to fit the needs of your specific application. Once you've defined your routes, you can use the rails routes command to see a list of all the routes that have been generated.