[英]How to update dependent table in Entity Framework in TPT mapping
我有这个模型:
public class Person
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public class Student : Person
{
public string Code { get; set; }
}
和这种情况:
public class Context : DbContext
{
public Context()
: base("Context")
{
Database.SetInitializer<Context>(null);
}
public DbSet<Student> Students { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Person>().ToTable("People");
modelBuilder.Entity<Student>().ToTable("Students");
}
}
而且我希望能够先插入一个不带代码的Student
实例,然后在以后的某个将来再更新该Student
的代码。 这是一个简单的代码说明:
var student = new Student
{
FirstName = "Saeed",
LastName = "Nemati",
};
using (var context = new Context())
{
context.Students.Add(student);
context.SaveChanges();
}
// A month later I want to update the code
var student2 = new Student
{
Id = student.Id,
Code = "something"
};
using (var context = new Context())
{
context.Students.Attach(student2);
context.Entry(student2).State = EntityState.Modified;
context.SaveChanges();
}
问题是,EF抱怨, FirstName
和LastName
应提供和不能为空。 我可以从Person
属性填充Student
继承的属性,但这听起来很臭。 EF中是否有任何方法或技术可以单独更新派生类(依赖表)?
这很简单。修改状态后, student2
实体框架会认为FirstName
和LastName
为null。 而是使用:
context.Entry(student2).State = EntityState.Modified;
您应该更改Property
:
context.Entry(student2).Property(x => x.Code).IsModified = true;
尝试这个:
using (var context = new Context())
{
var student2 = context.Students.SingleOrDefault(x=>x.Id == yourID);
student2.Code = "Something";
context.Students.Attach(student2);
context.Entry(student2).State = EntityState.Modified;
context.SaveChanges();
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.