Ruby on Rails CRUD操作图解 _数据库操作

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。