Entity Framework 自动生成CodeFirst代码

前言

在前面的文章中我们提到Entity Framework的“Code First”模式也同样可以基于现有数据库进行开发。今天就让我们一起看一下使用Entity Framework Power Tools如何基于现有数据库生成数据类和数据库上下等。

Entity Framework Power Tools

基于现有数据库生成POCO数据类和数据库上下文需要借助Visual Studio一个扩展插件-- Entity Framework Power Tools（一个Code First反向工程工具）。

 

通过点击上图的扩展和更新，得到如下图所示的界面

安装完之后只要在项目上右键选择Entity Framework->Reverse Engineer Code First（项目中首先需要安装Entity Framework 包，否则会有错误），然后在弹出的窗口中输入相关的数据库连接信息即可（我们这里使用“NorthWind”数据库）。

当然当你在操作的时候你首先还是要先引用Entity Framework。然后点击Reverse Engineer Code First

配置好数据库链接，

确认之后，我们首先来看一下配置文件的变化

"1.0" encoding="utf-8"?>              "entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />           "NorthwindContext" connectionString="Data Source=.;Initial Catalog=Northwind;Integrated Security=True;MultipleActiveResultSets=True"       providerName="System.Data.SqlClient" />           "v4.0" sku=".NETFramework,Version=v4.5" />           "System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">                "v11.0" />

 于此同时生成了NorthWindContext数据库操作上下文

using System.Data.Entity; using System.Data.Entity.Infrastructure; using CodeFirstPowerTools.Models.Mapping;   namespace CodeFirstPowerTools.Models {     public partial class NorthwindContext : DbContext     {         static NorthwindContext()         {             Database.SetInitializer(null);         }           public NorthwindContext()             : base("Name=NorthwindContext")         {         }           public DbSet Categories { get; set; }         public DbSet CustomerDemographics { get; set; }         public DbSet Customers { get; set; }         public DbSet Employees { get; set; }         public DbSet Order_Details { get; set; }         public DbSet Orders { get; set; }         public DbSet Products { get; set; }         public DbSet Regions { get; set; }         public DbSet Shippers { get; set; }         public DbSet Suppliers { get; set; }         public DbSet Territories { get; set; }         public DbSet Alphabetical_list_of_products { get; set; }         public DbSet Category_Sales_for_1997 { get; set; }         public DbSet Current_Product_Lists { get; set; }         public DbSet Customer_and_Suppliers_by_Cities { get; set; }         public DbSet Invoices { get; set; }         public DbSet Order_Details_Extendeds { get; set; }         public DbSet Order_Subtotals { get; set; }         public DbSet Orders_Qries { get; set; }         public DbSet Product_Sales_for_1997 { get; set; }         public DbSet Products_Above_Average_Prices { get; set; }         public DbSet Products_by_Categories { get; set; }         public DbSet Sales_by_Categories { get; set; }         public DbSet Sales_Totals_by_Amounts { get; set; }         public DbSet Summary_of_Sales_by_Quarters { get; set; }         public DbSet Summary_of_Sales_by_Years { get; set; }           protected override void OnModelCreating(DbModelBuilder modelBuilder)         {             modelBuilder.Configurations.Add(new CategoryMap());             modelBuilder.Configurations.Add(new CustomerDemographicMap());             modelBuilder.Configurations.Add(new CustomerMap());             modelBuilder.Configurations.Add(new EmployeeMap());             modelBuilder.Configurations.Add(new Order_DetailMap());             modelBuilder.Configurations.Add(new OrderMap());             modelBuilder.Configurations.Add(new ProductMap());             modelBuilder.Configurations.Add(new RegionMap());             modelBuilder.Configurations.Add(new ShipperMap());             modelBuilder.Configurations.Add(new SupplierMap());             modelBuilder.Configurations.Add(new TerritoryMap());             modelBuilder.Configurations.Add(new Alphabetical_list_of_productMap());             modelBuilder.Configurations.Add(new Category_Sales_for_1997Map());             modelBuilder.Configurations.Add(new Current_Product_ListMap());             modelBuilder.Configurations.Add(new Customer_and_Suppliers_by_CityMap());             modelBuilder.Configurations.Add(new InvoiceMap());             modelBuilder.Configurations.Add(new Order_Details_ExtendedMap());             modelBuilder.Configurations.Add(new Order_SubtotalMap());             modelBuilder.Configurations.Add(new Orders_QryMap());             modelBuilder.Configurations.Add(new Product_Sales_for_1997Map());             modelBuilder.Configurations.Add(new Products_Above_Average_PriceMap());             modelBuilder.Configurations.Add(new Products_by_CategoryMap());             modelBuilder.Configurations.Add(new Sales_by_CategoryMap());             modelBuilder.Configurations.Add(new Sales_Totals_by_AmountMap());             modelBuilder.Configurations.Add(new Summary_of_Sales_by_QuarterMap());             modelBuilder.Configurations.Add(new Summary_of_Sales_by_YearMap());         }     } }

 最终来查看一下生成的文件

代码调用实例

 

using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; using CodeFirstPowerTools.Models;   namespace CodeFirstPowerTools {     class Program     {         static void Main(string[] args)         {             using (var db = new NorthwindContext())             {                 IQueryable orders = from order in db.Orders                                            where order.OrderID < 10256                                            select order;                 foreach (Order order in orders)                 {                     Console.WriteLine(order.ShipCity);                 }             }             Console.ReadLine();         }     } }

 执行后结果如下

 

 

简单的使用到此为止。