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
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=5.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
</configSections>
<connectionStrings>
<add name="NorthwindContext" connectionString="Data Source=.;Initial Catalog=Northwind;Integrated Security=True;MultipleActiveResultSets=True"
providerName="System.Data.SqlClient" />
</connectionStrings>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
<parameters>
<parameter value="v11.0" />
</parameters>
</defaultConnectionFactory>
</entityFramework>
</configuration>
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<NorthwindContext>(null);
}
public NorthwindContext()
: base("Name=NorthwindContext")
{
}
public DbSet<Category> Categories { get; set; }
public DbSet<CustomerDemographic> CustomerDemographics { get; set; }
public DbSet<Customer> Customers { get; set; }
public DbSet<Employee> Employees { get; set; }
public DbSet<Order_Detail> Order_Details { get; set; }
public DbSet<Order> Orders { get; set; }
public DbSet<Product> Products { get; set; }
public DbSet<Region> Regions { get; set; }
public DbSet<Shipper> Shippers { get; set; }
public DbSet<Supplier> Suppliers { get; set; }
public DbSet<Territory> Territories { get; set; }
public DbSet<Alphabetical_list_of_product> Alphabetical_list_of_products { get; set; }
public DbSet<Category_Sales_for_1997> Category_Sales_for_1997 { get; set; }
public DbSet<Current_Product_List> Current_Product_Lists { get; set; }
public DbSet<Customer_and_Suppliers_by_City> Customer_and_Suppliers_by_Cities { get; set; }
public DbSet<Invoice> Invoices { get; set; }
public DbSet<Order_Details_Extended> Order_Details_Extendeds { get; set; }
public DbSet<Order_Subtotal> Order_Subtotals { get; set; }
public DbSet<Orders_Qry> Orders_Qries { get; set; }
public DbSet<Product_Sales_for_1997> Product_Sales_for_1997 { get; set; }
public DbSet<Products_Above_Average_Price> Products_Above_Average_Prices { get; set; }
public DbSet<Products_by_Category> Products_by_Categories { get; set; }
public DbSet<Sales_by_Category> Sales_by_Categories { get; set; }
public DbSet<Sales_Totals_by_Amount> Sales_Totals_by_Amounts { get; set; }
public DbSet<Summary_of_Sales_by_Quarter> Summary_of_Sales_by_Quarters { get; set; }
public DbSet<Summary_of_Sales_by_Year> 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<Order> 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。
