1、创建新项目并引入Entity Framework
然后就可以开始使用EF了
开始使用一对多
Users 用户类,UserDetail用户详情类:一个用户对应多个详情(仅用于测试)
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1 public class UserDetail 2 { 3 public int DetailId { get; set; } 4 public string NAME { get; set; } 5 public int uid { get; set; } 6 public string remark { get; set; } 7 public virtual Users user { get; set; } 8 } 9 public class Users 10 { 11 public int id { get; set; } 12 public string Name { get; set; } 13 public int Age { get; set; } 14 public DateTime Birth { get; set; } 15 public virtual ICollection<UserDetail> detail { get; set; } 16 17 }
ObjectContext类:
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1 public class ObjectContext : DbContext 2 { 3 public ObjectContext() 4 : base("server=.;uid=xx;pwd=xxx;database=XXX") 5 { 6 7 } 8 protected override void OnModelCreating(DbModelBuilder modelBuilder) 9 { 10 base.OnModelCreating(modelBuilder); 11 modelBuilder.Entity<Users>().HasKey(p => p.id); 12 modelBuilder.Entity<UserDetail>().ToTable("UserDetail"); 13 modelBuilder.Entity<UserDetail>().HasKey(p => p.DetailId); 14 modelBuilder.Entity<UserDetail>().Property(p => p.NAME).HasColumnName("NAME"); 15 modelBuilder.Entity<UserDetail>().HasRequired(p => p.user).WithMany(p => p.detail).HasForeignKey(p => p.uid); 16 } 17 public DbSet<Users> users { get; set; } 18 public DbSet<UserDetail> userdetail { get; set; } 19 20 }
查询方法:
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1 public void GetAll() 2 { 3 using (ObjectContext db = new ObjectContext()) 4 { 5 var users = (from a in db.users select a).ToList<Users>(); 6 for (int i = 0; i < users.Count; i++) 7 { 8 Console.WriteLine("ID:"+users[i].id+",Name:"+users[i].Name); 9 foreach (var item in users[i].detail) 10 { 11 Console.WriteLine(" id:" + item.DetailId + ",NAME" + item.NAME); 12 } 13 } 14 } 15 }
删除和修改子集同时进行方法
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1 public void Update() 2 { 3 using (ObjectContext db = new ObjectContext()) 4 { 5 var users = (from a in db.users where a.id == 1 select a).First(); 6 //删除子集 7 var detailitem=users.detail.Where(p=>p.DetailId==7).FirstOrDefault(); 8 db.Entry(detailitem).State = System.Data.Entity.EntityState.Deleted; 9 users.detail.Remove(detailitem); 10 //修改子集 11 var detailitem2 = users.detail.Where(p=>p.DetailId==2).FirstOrDefault(); 12 detailitem2.NAME = "这是修改后的数据"; 13 db.Entry(detailitem2).State = System.Data.Entity.EntityState.Modified; 14 db.SaveChanges(); 15 } 16 }
然后是对多对
新增一个角色类 Roles
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1 public class Roles 2 { 3 public Roles() 4 { 5 users = new HashSet<Users>(); 6 } 7 public int RoleID { get; set; } 8 public string RoleName { get; set; } 9 public string Remark { get; set; } 10 public virtual ICollection<Users> users { get; set; } 11 }
修改ObjectContext类:
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1 modelBuilder.Entity<Roles>().HasKey(p => p.RoleID); 2 //modelBuilder.Entity<UserRoles>().HasKey(p => p.ID); 3 modelBuilder.Entity<Roles>().HasMany(p => p.users).WithMany(p => p.roles).Map( 4 p => 5 { 6 p.MapLeftKey("RoleId"); 7 p.MapRightKey("UserId"); 8 p.ToTable("UserRoles"); 9 });
写测试方法:
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1 public static void AddUserRole() 2 { 3 using (ObjectContext db = new ObjectContext()) 4 { 5 //添加一个用户 两个角色 6 var user = new Users() { Name = "Test用户1", Age = 20, Birth = DateTime.Now }; 7 var role1 = new Roles() { RoleName = "Test角色1" }; 8 var role2 = new Roles() { RoleName = "Test角色2" }; 9 user.roles.Add(role1); 10 user.roles.Add(role2); 11 db.users.Add(user); 12 db.SaveChanges(); 13 } 14 }
查询:
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1 public static void GetAllUserRoles() 2 { 3 using (ObjectContext db = new ObjectContext()) 4 { 5 var users = (from a in db.users select a).ToList<Users>(); 6 if (users != null) 7 { 8 Console.WriteLine("User查询结果:"); 9 foreach (var item in users) 10 { 11 Console.WriteLine("UserID:" + item.id + ",UserName:" + item.Name + ",Birth:" + item.Birth); 12 if (item.roles != null) 13 { 14 foreach (var role in item.roles) 15 { 16 Console.WriteLine(" RoleId:" + role.RoleID + ",RoleNmae:" + role.RoleName + ",UserId:" + item.id); 17 } 18 } 19 } 20 } 21 var roles = (from a in db.roles select a).ToList<Roles>(); 22 if (roles != null) 23 { 24 Console.WriteLine("Role查询结果:"); 25 foreach (var item in roles) 26 { 27 Console.WriteLine("RoleID:" + item.RoleID + ",RoleName:" + item.RoleName); 28 if (item.users != null) 29 { 30 foreach (var user in item.users) 31 { 32 Console.WriteLine(" UserID:" + user.id + ",UserName:" + user.Name + ",Birth:" + user.Birth + ",RoleID:" + item.RoleID); 33 } 34 } 35 } 36 } 37 } 38 }
然后写完测试。。。
源代码:EFDemo