Ruby on Rails CRUD

CRUD stands for Create, Read, Update and Delete data in a database. Active Record automatically allows an application to read and manipulate data stored within tables.

In this tutorial, we will create a Rails CRUD with MySQL database.

Step 1 Create a new Rails application.

Step 2 Change your directory to crud.

Step 3 Go to the Gemfile in your application and add the following.

Step 4 Go to the config/application.rb file in your application and add the following.

config.paths.add File.join('app', 'api'), glob: File.join('**', '*.rb')
config.autoload_paths += Dir[Rails.root.join('app', 'api', '*')]

Step 5 Run the following command:

Step 6 Go to app/views/layouts/application.html.erb and insert the following lines in head tag.

<%= stylesheet_link_tag??? 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css' %>
<%= stylesheet_link_tag??? 'https://cdn.datatables.net/s/dt/dt-1.10.10,r-2.0.0/datatables.min.css' %>

Step 7 Go to app/views/layouts/application.html.erb and insert the following lines before </body> tag.

<%= javascript_include_tag 'https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/js/bootstrap.min.js' %>
<%= javascript_include_tag 'https://cdn.datatables.net/s/dt/dt-1.10.10,r-2.0.0/datatables.min.js' %>

Step 8 In the above file, replace <%= yield %> with following code:

<div class="container">
<div><% if flash[:notice] %>
<div><%= flash[:notice] %></div>
<% end %> <%= yield %></div>
</div>
</div>

Step 9 Go to app/assets/javascripts/application.js and add the javascript code that loads jQuery DataTable:

var ready = function() {
 $('#products').DataTable({
  "columnDefs": [
     { "width": "19%", className: "dt-body-center", "targets": -1 },
     { "width": "10%", "targets": 0 },
     { "width": "7%", "targets": 1 },
     { "width": "20%", "targets": 2 },
     { "width": "20%", "targets": 3 },
    ]
   });
}
$(document).ready(ready);
$(document).on('page:load', ready);

Step 10 Create a controller from the console.

Step 11 Create a model from the console.

rails g model product name:string price:decimal short_description:text full_description:text

Step 12 Go to app/controllers/products_controller.rb and write the following code.

class ProductsController < ApplicationController 
 
  # GET method to get all products from database 
  def index 
    @products = Product.all 
  end 
 
  # GET method to get a product by id 
  def show 
    @product = Product.find(params[:id]) 
  end 
 
  # GET method for the new product form 
  def new 
    @product = Product.new 
  end 
 
  # POST method for processing form data 
  def create 
    @product = Product.new(product_params) 
    if @product.save 
      flash[:notice] = 'Product added!' 
      redirect_to root_path 
    else 
      flash[:error] = 'Failed to edit product!' 
      render :new 
    end 
  end 
 
   # GET method for editing a product based on id 
  def edit 
    @product = Product.find(params[:id]) 
  end 
 
  # PUT method for updating in database a product based on id 
  def update 
    @product = Product.find(params[:id]) 
    if @product.update_attributes(product_params) 
      flash[:notice] = 'Product updated!' 
      redirect_to root_path 
    else 
      flash[:error] = 'Failed to edit product!' 
      render :edit 
    end 
  end 
 
  # DELETE method for deleting a product from database based on id 
  def destroy 
    @product = Product.find(params[:id]) 
    if @product.delete 
      flash[:notice] = 'Product deleted!' 
      redirect_to root_path 
    else 
      flash[:error] = 'Failed to delete this product!' 
      render :destroy 
    end 
  end 
 
  # we used strong parameters for the validation of params 
  def product_params 
    params.require(:product).permit(:name, :price, :old_price, :short_description, :full_description) 
  end 
 
end

Step 13 Go to app/models/product.rb and make some validations on the name, price and description fields.

class Product < ApplicationRecord 
validates :name, presence: true 
validates :price, presence: true, numericality: {:greater_than => 0} 
validates :short_description, presence: true 
end 

Step 14 Go to config/routes.rb and add:

resources :products
root 'products#index'

Step 14 Go to config/routes.rb and add:

resources :products
root 'products#index'

Step 15 Now create a folder named api in app folder. Inside this folder create a folder named products. Now finally create app/api/products/products_api.rb file and add the following code.

module Products 
  class ProductsAPI < Grape::API 
 
    format :json 
 
    desc "Product List", { 
        :notes => <<-NOTE 
        Get All Products 
         __________________ 
        NOTE 
    } 
 
    get do 
      Product.all 
    end 
 
 
    desc "Product By Id", { 
        :notes => <<-NOTE 
        Get Product By Id 
         __________________ 
        NOTE 
    } 
 
    params do 
      requires :id, type: Integer, desc: "Product id" 
    end 
 
    get ':id' do 
      begin 
        product = Product.find(params[:id]) 
      rescue ActiveRecord::RecordNotFound 
        error!({ status: :not_found }, 404) 
      end 
    end 
 
    desc "Delete Product By Id", { 
        :notes => <<-NOTE 
        Delete Product By Id 
         __________________ 
        NOTE 
    } 
 
    params do 
      requires :id, type: Integer, desc: "Product id" 
    end 
 
    delete ':id' do 
      begin 
        product = Product.find(params[:id]) 
        { status: :success } if product.delete 
      rescue ActiveRecord::RecordNotFound 
        error!({ status: :error, message: :not_found }, 404) 
      end 
    end 
 
    desc "Update Product By Id", { 
        :notes => <<-NOTE 
        Update Product By Id 
                        __________________ 
        NOTE 
    } 
 
    params do 
      requires :id, type: Integer, desc: "Product id" 
      requires :name, type: String, desc: "Product name" 
      requires :price, type: BigDecimal, desc: "Product price" 
      optional :old_price, type: BigDecimal, desc: "Product old price" 
      requires :short_description, type: String, desc: "Product old price" 
      optional :full_description, type: String, desc: "Product old price" 
    end 
 
    put ':id' do 
      begin 
        product = Product.find(params[:id]) 
        if product.update({ 
                              name: params[:name], 
                              price: params[:price], 
                              old_price: params[:old_price], 
                              short_description: params[:short_description], 
                              
                          }) 
          { status: :success } 
        else 
          error!({ status: :error, message: product.errors.full_messages.first }) if product.errors.any? 
        end 
 
 
      rescue ActiveRecord::RecordNotFound 
        error!({ status: :error, message: :not_found }, 404) 
      end 
    end 
 
 
    desc "Create Product", { 
        :notes => <<-NOTE 
        Create Product 
         __________________ 
        NOTE 
    } 
 
    params do 
      requires :name, type: String, desc: "Product name" 
      requires :price, type: BigDecimal, desc: "Product price" 
      optional :old_price, type: BigDecimal, desc: "Product old price" 
      requires :short_description, type: String, desc: "Product old price" 
    
    end 
 
    post do 
      begin 
        product =  Product.create({ 
                                      name: params[:name], 
                                      price: params[:price], 
                                      old_price: params[:old_price], 
                                      short_description: params[:short_description], 
                                      
                                  }) 
        if product.save 
          { status: :success } 
        else 
          error!({ status: :error, message: product.errors.full_messages.first }) if product.errors.any? 
        end 
 
 
      rescue ActiveRecord::RecordNotFound 
        error!({ status: :error, message: :not_found }, 404) 
      end 
    end 
  end 
end

Step 16 Go to config/routes.rb and add the following code.

Step 17 Run following command in your console.

Step 18 In app/views/products/ file, write the following code.

index.html.erb

<!DOCTYPE html> 
<html> 
<body> 
 <div class="container"> 
    <h3>STOCK LIST</h3> 
   
      <div> 
        <%= link_to 'Add Product', new_product_path %> 
      </div> 
      <br> 
    <table border="2"> 
      <thead> 
      <tr> 
        <th>Name</th> 
        <th>Price</th> 
        <th>Description</th> 
        <th>Actions</th> 
      </tr> 
      </thead> 
      <tbody> 
      <% @products.each do |product| %> 
          <tr> 
            <td><%= product.name %></td> 
            <td><%= product.price %></td> 
            <td><%= truncate(product.short_description, :length => 75) %></td> 
               <div> 
               <td> 
                <%= link_to 'Show', product_path(product) %> 
                <%= link_to 'Edit', edit_product_path(product) %> 
                <%= link_to 'Delete', product_path(product), method: :delete %> 
              </div> 
            </td> 
          </tr> 
      <% end %> 
      </tbody> 
    </table> 
    </div> 
  </body> 
</html>

new.html.erb

<div class="container"> 
  <%= form_for @product, url: {action: :create} do |f| %> 
      <div> 
        <h3>Add a Product</h3> 
      </div> 
      <div> 
        <p> 
          <%= "<div>#{@product.errors.full_messages.first}</div>".html_safe if @product.errors.any? %> 
        <div> 
            <label>Product Name</label> 
              <%= f.text_field :name %> 
        </div> 

        <div> 
             <label>Price</label> 
             <%= f.text_field :price %> 
        </div> 

        <div> 
           <label>Description</label> 
              <%= f.text_field :short_description %> 
        </div> 
		 </p> 
      </div> 
      <div> 
        <%= link_to 'Back', { controller: 'products', action: 'index'} %> 
        <%= f.submit 'Create Product' %> 
      </div> 
  <% end %> 
</div>

edit.html.erb

show.html.erb

<div class="container">      
        <h3>Add a Product</h3> 
     
            <div> 
              <label>Product Name</label> 
              <%= @product.name %> 
            </div> 

            <div> 
              <label>Price</label> 
              <%= @product.price %> 
            </div> 
          
            <div> 
              <label>Description</label> 
              <%= @product.short_description %> 
            </div> 
       
      <div> 
        <%= link_to 'Back', { controller: 'products', action: 'index'} %> 
      </div> 
</div>

Step 19 Start the server from the command line.

Step 20 Run the application on your localhost.

Following page will appear. Here we have already inserted some data in the table.