Ruby on Rails CRUD操作图解

CRUD代表创建, 读取, 更新和删除数据库中的数据。 Active Record自动允许应用程序读取和操作表中存储的数据。

在本教程中, 我们将使用MySQL数据库创建一个Rails CRUD。

步骤1创建一个新的Rails应用程序。

rails new crud

步骤2将目录更改为crud。

cd crud

步骤3转到应用程序中的Gemfile并添加以下内容。

gem 'grape'

步骤4转到应用程序中的config / application.rb文件, 然后添加以下内容。

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

步骤5运行以下命令：

bundle install

步骤6转到app / views / layouts / application.html.erb并将以下行插入head标签。

<%= 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' %>

步骤7转到app / views / layouts / application.html.erb并将以下行插入</ body>标记之前。

<%= 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' %>

步骤8在上面的文件中, 将<％= yield％>替换为以下代码：

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

步骤9转到app / assets / javascripts / application.js并添加加载jQuery DataTable的javascript代码：

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);

步骤10从控制台创建一个控制器。

rails g controller products index show new create edit update destroy

步骤11从控制台创建模型。

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

步骤12转到app / controllers / products_controller.rb并编写以下代码。

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

步骤13转到app / models / product.rb并在名称, 价格和描述字段中进行一些验证。

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

步骤14转到config / routes.rb并添加：

resources :products
root 'products#index'

步骤14转到config / routes.rb并添加：

resources :products
root 'products#index'

步骤15现在在应用程序文件夹中创建一个名为api的文件夹。在此文件夹中, 创建一个名为product的文件夹。现在, 终于创建了app / api / products / products_api.rb文件并添加以下代码。

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

步骤16转到config / routes.rb并添加以下代码。

mount Products::ProductsAPI => '/api/products'

步骤17在控制台中运行以下命令。

rake db:migrate

步骤18在app / views / products /文件中, 编写以下代码。

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

<div class =” container”> <％= form_for @product, 网址：{action：：update} do | f | ％> <h3>添加产品</ h3> <％=” <div>＃{@ product.errors.full_messages.first} </ div>”。html_safe, 如果@ product.errors.any？ ％> <p> <div> <label>产品名称</ label> <％= f.text_field：name％> </ div> <div> <label> Price </ label> <％= f.text_field：price ％> </ div> <div> <label>描述</ label> <％= f.text_field：short_description％> </ div> </ p> <div> <％= link_to’Back’, {controller：’产品”, 操作：’index’}％> <％= f。提交’Update Product’％> </ div> <％end％> </ div>

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>

步骤19从命令行启动服务器。

rails s

步骤20在本地主机上运行该应用程序。

localhost:3000/products

将出现以下页面。在这里, 我们已经在表中插入了一些数据。

插入资料

要插入数据, 请单击以上快照中所示的”添加产品”。如下所示填写详细信息。

读取资料

要读取数据, 请单击操作显示。在这里, 我们将单击”跳伞表演”动作。

更新资料

要更新数据, 请单击”编辑操作”。在这里, 我们将编辑从男式正装衬衫到女式正装衬衫的衬衫描述。

删除资料

要删除数据, 请单击”删除”操作。在这里, 我们将从上表中删除产品牛仔裤。

下载

下载此示例