Question

以下是现有记录的保存例程。这有什么问题？我正在使用independent association

没有发出错误，但是Person表上的Country_CountryId字段没有更改，其他所有字段都被正确保留。以下代码/方法有什么问题？

public JsonResult SaveUpdate(Person p)
{
    p.Country = new Country { CountryId = new Guid("EF0CD98E-7138-4757-866E-ADC3C8D216DA") };

    using (var db = new TheDbContext())
    {
        db.Entry(p).State = System.Data.EntityState.Modified;                
        db.SaveChanges();       
    }

}

这是我的映射器：

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    base.OnModelCreating(modelBuilder);

    modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();

    modelBuilder.Entity<Person>().HasRequired(x => x.Country)
        .WithMany(x => x.Persons)
        .Map(x => x.MapKey("Country_CountryId"));

    modelBuilder.Entity<Person>().Property(x => x.RowVersion).IsRowVersion();


    modelBuilder.Entity<Country>().HasKey(x => x.CountryId);

}

这是我的模特：

public class Country
{
    public virtual Guid CountryId { get; set; }

    public virtual string CountryCode { get; set; }
    public virtual string CountryName { get; set; }

    public virtual IList<Person> Persons { get; set; }
}


public class Person
{
    public virtual Guid PersonId { get; set; }
    public virtual string Username { get; set; }

    public virtual string Firstname { get; set; }
    public virtual string Lastname { get; set; }
    public virtual byte[] RowVersion { get; set; }


    public virtual Country Country { get; set; }
}

Answer 1

使用它代替，它将起作用：

public JsonResult SaveUpdate(Person p)
{
    var country = new Country { CountryId = new Guid("EF0CD98E-7138-4757-866E-ADC3C8D216DA") };

    using (var db = new TheDbContext())
    {
        db.People.Attach(p);
        db.Countries.Attach(country);
        db.Entry(p).State = System.Data.EntityState.Modified;                
        p.Country = country;
        db.SaveChanges();       
    }
}

独立关联需要特别小心，因为每个关联本身都有自己必须配置的状态。

在EF 4.1上使用独立关联方法时，不保存导航属性

1 个答案: