6 - Criando Seeders

Para criarmos seeders para preencher nossas tabelas automaticamente podemos fazer como nas migrations. Gere o seeder com o comando abaixo:

npx sequelize-cli seed:generate --name seed-categories-table

Agora vamos preencher o seeder da tabela categories:
- Obs.: O seeder utiliza a mesma estrutura da migration, um objeto com um método up para quando for executar e um método down para quando for reverter os seeds.

// src/database/seeders/XXXXXXXXXXXXXX-seed-categories-table.js

'use strict';

module.exports = {
  async up(queryInterface, Sequelize) {
    await queryInterface.bulkInsert('categories', [
      { name: 'Tecnologias Back-end', position: 1, created_at: new Date(), updated_at: new Date() },
      { name: 'Tecnologias Front-end', position: 2, created_at: new Date(), updated_at: new Date() },
      { name: 'Ferramentas de Desenvolvimento', position: 3, created_at: new Date(), updated_at: new Date() },
      { name: 'Soft-skills', position: 4, created_at: new Date(), updated_at: new Date() },
      { name: 'Carreira', position: 5, created_at: new Date(), updated_at: new Date() },
    ], {})
  },

  async down(queryInterface, Sequelize) {
    await queryInterface.bulkDelete('categories', null, {})
  }
};

Depois disso vamos criar um seeder para a tabela courses:

npx sequelize-cli seed:generate --name seed-courses-table

E então vamos adicionar o seu conteúdo, primeiro obtendo as categorias existentes e então criando cursos para cada uma delas:

// src/database/seeders/XXXXXXXXXXXXXX-seed-courses-table.js

'use strict';

module.exports = {
  async up (queryInterface, Sequelize) {
    const [categories] = await queryInterface.sequelize.query('SELECT id FROM categories;')

    await queryInterface.bulkInsert('courses', [
      { name: 'Programador Full-stack Javascript', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', featured: true, category_id: categories[0].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Dominando a Linguagem Ruby', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', category_id: categories[0].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Micro-serviços com Node.js', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', featured: true, category_id: categories[0].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Criando APIs Profissionais com Ruby on Rails', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', featured: true, category_id: categories[0].id, created_at: new Date(), updated_at: new Date() },
      { name: 'TDD na Prática: Testando APIs Node.js', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', featured: true, category_id: categories[0].id, created_at: new Date(), updated_at: new Date() },
      { name: 'TDD na Prática: Testando Aplicações React', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', featured: true, category_id: categories[1].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Especialista Front-end: Vue.js', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', category_id: categories[1].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Criando Sites e Apps 3D com Three.js', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', category_id: categories[1].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Dominando o Bootstrap 5', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', category_id: categories[1].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Visual Studio Code para Programadores Javascript', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', category_id: categories[2].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Comandos do Terminal Linux: Um Guia Completo', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', category_id: categories[2].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Comunicação e Trabalho em Equipe', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', category_id: categories[3].id, created_at: new Date(), updated_at: new Date() },
      { name: 'Programador Nômade', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', featured: true, category_id: categories[4].id, created_at: new Date(), updated_at: new Date() },
      { name: 'O Guia do Programador Freelancer', synopsis: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.', category_id: categories[4].id, created_at: new Date(), updated_at: new Date() },
    ])
  },

  async down (queryInterface, Sequelize) {
    await queryInterface.bulkDelete('courses', null, {})
  }
};

Por fim, só precisamos rodar os seeder com o comando:

npx sequelize-cli db:seed:all

Esses seeds não irão incluir as capas dos cursos, mas você pode fazer isso através do painel do AdminJS.