Question

CodeFirst中DbContext能够动态添加DbSet么

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.Entity;
using System.ComponentModel.DataAnnotations;
using System.Data.Entity.ModelConfiguration;
using System.Data.Entity.ModelConfiguration.Configuration;
namespace CodeFirstDemo
{
/// <summary>
/// 实体注册Helper接口
/// </summary>
public interface IEntityRegstHelper
{
void RegTo(ConfigurationRegistrar confRegistrar);
}
// 客户
public class Customer
{
public int CustomerID { get; set; }
public String CustomerName { get; set; }
public string Address { get; set; }
}
// 客户实体的注册Helper
public class CustomerRegstHelper : IEntityRegstHelper
{
public void RegTo(ConfigurationRegistrar confRegistrar)
{
confRegistrar.Add<Customer>(new EntityTypeConfiguration<Customer>());
}
}
public class MyDbContext : DbContext
{
List<IEntityRegstHelper> entityRegstHelperlist;
// 添加实体注册
public void AddEntityRegHelper(IEntityRegstHelper r)
{
if (entityRegstHelperlist == null)
entityRegstHelperlist = new List<IEntityRegstHelper>();
entityRegstHelperlist.Add(r);
}
//public DbSet<Customer> Customers { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
// 动态地加入实体
if (entityRegstHelperlist != null)
{
foreach (IEntityRegstHelper r in entityRegstHelperlist)
r.RegTo(modelBuilder.Configurations);
}
}
}
class Program
{
static void Main(string[] args)
{
using (var db = new MyDbContext())
{
db.AddEntityRegHelper(new CustomerRegstHelper());
var c = new Customer()
{
CustomerName = "长沙市大风通讯有限公司",
Address = "长沙市"
};
db.Set<Customer>().Add(c);
db.SaveChanges();
var query = from customer in db.Set<Customer>()
select customer;
foreach (var cq in query)
{
Console.WriteLine("客户: {0}, 地址：{1}", cq.CustomerName, cq.Address);
}
Console.WriteLine("按任意键退出");
Console.ReadKey();
}
}
}
}