[Rails] Implementation of category function

Target

Development environment

・ Ruby: 2.5.7 Rails: 5.2.4 ・ Vagrant: 2.2.7 -VirtualBox: 6.1 ・ OS: macOS Catalina

Premise

The following has been implemented.

・ Slim introduction ・ Introduction of Bootstrap3 ・ Implementation of posting function

Implementation

1. Model

** ① Create a category model table **

Terminal

$ rails g model Category name:string

Terminal

$ rails db:migrate

schema.rb

create_table "categories", force: :cascade do |t|
  t.string "name"
  t.datetime "created_at", null: false
  t.datetime "updated_at", null: false
end

** ② Add a column to the books table **

Terminal

$ rails g migration AddCategoryIdToBooks category_id:integer

Terminal

$ rails db:migrate

schema.rb

  create_table "books", force: :cascade do |t|
    t.integer "user_id"
    t.string "title"
    t.text "body"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.integer "category_id"
  end

** ③ Edit each model **

book.rb

#Postscript
has_many :categories, dependent: :destroy

dependent: :destroy ➡︎ When the corresponding category is deleted, the linked book is also deleted.

category.rb

#Postscript
belongs_to :book

2. Controller

** ① Create and edit categories_controller.rb **

Create index and edit views in advance.

Terminal

$ rails g controller categories index edit

categories_controller.rb

class CategoriesController < ApplicationController
  before_action :set_category, only: [:edit, :update, :destroy]

  def index
    @category = Category.new
    @categories = Category.all
  end

  def create
    @category = Category.new(category_params)
    if @category.save
      redirect_to categories_path
    else
      @categories = Category.all
      render 'index'
    end
  end

  def edit
  end

  def update
    if @category.update(category_params)
      redirect_to categories_path
    else
      render 'edit'
    end
  end

  def destroy
    @category.destroy
    redirect_to categories_path
  end

  private

    def set_category
      @category = Category.find(params[:id])
    end

    def category_params
      params.require(:category).permit(:name)
    end
end

** ② Add category_id to the strong parameter of books_controller.rb **

books_controller.rb

def book_params
  params.require(:book).permit(:title, :body, :category_id)
end

3. Routing

routes.rb

#Postscript
resources :categories, except: [:new, :show]

except: [:new, :show] ➡︎ Add actions other than new and show to the routing.

4. View

slim:categories/index.html.slim

.row

  .col-xs-3
    = form_with model: @category, local: true do |f|

      = f.label :name, 'Category name'
      br
      = f.text_field :name, class:'form-control'
      br

      = f.submit 'add to', class: 'btn btn-primary btn-block'

  .col-xs-9
    table.table
      thead
        tr
          th
            |Category name
          th
          th

      tbody
        - @categories.each do |category|
          tr
            td
              = category.name
            td
              = link_to 'Edit', edit_category_path(category), class: 'btn-sm btn-primary'
            td
              = link_to 'Delete', category_path(category), method: :delete, data: { confirm: '本当にDeleteしますか？' }, class: 'btn-sm btn-danger'

slim:categories/edit.html.slim

.row
  .col-xs-3

  .col-xs-6
    = form_with model: @category, local: true do |f|

      = f.label :name, 'Category name'
      br
      = f.text_field :name, class:'form-control'
      br

      = f.submit 'Save', class: 'btn btn-primary btn-block'

  .col-xs-3

slim:books/index.html.slim

.row
  .col-xs-3
    = form_with model: @book, local: true do |f|

      = f.label :title, 'title'
      br
      = f.text_field :title, class:'form-control'
      br

      = f.label :body, 'Text'
      br
      = f.text_area :body, class:'form-control'
      br

      /Postscript
      = f.label :category_id, 'Category'
      br
      = f.collection_select :category_id, Category.all, :id, :name, { prompt: 'Please select' }, class: 'form-control'
      br

      = f.submit 'Post', class: 'btn btn-primary btn-block'

  .col-xs-9
    table.table
      thead
        tr
          th
            |Contributor
          th
            |title
          th
            |Text
          /Postscript
          th
            |Category
          th

      tbody
        - @books.each do |book|
          tr
            td
              = link_to book.user  do
                = book.user.name
            td
              = link_to book.title, book_path(book)
            td
              = book.body
            /Postscript
            td
              = book.category.name
            td
              -if book.user == current_user
                = link_to 'Delete', book, method: :delete, data: { confirm: '本当にDeleteしてもよろしいですか？' }, class: 'btn-sm btn-danger'

= f.collection_select :category_id, Category.all, :id, :name ➡︎ The name of all categories is displayed in the pull-down menu, and the value is set to ʻid`.