[英]Entity Framework complex type inserting
我的代码有一个烦人的问题。 我的模特:
public class Option
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Conference> Conference { set; get; }
}
public partial class Conference
{
[Key, ForeignKey("User")]
public int UserId { get; set; }
public virtual Option Option { set; get; }
public virtual User User { get; set; }
}
public partial class User
{
public int Id {get; set; }
public string Name { get; set; }
public virtual Conference Conference { get; set; }
}
现在我通过dbSet.Find(id)(RepositoryFactory)从Db获取Option对象,我想要做的是保存新创建的User,但是选择了Option。
如果我这样做:
var option = dbSet.Find(id);
var user = new User()
{
Name = "Name",
Conference = new Conference
{
Option = option
}
};
//...
context.SaveChanges();
我遇到一个例外:IEntityChangeTracker的多个实例不能引用一个实体对象。
我做错了什么?
编辑:我试图创建映射,但这似乎也不起作用。
modelBuilder.Entity<Conference>()
.HasKey(x => x.UserId)
.HasRequired(x => x.User)
.WithOptional(user => user.Conference);
modelBuilder.Entity<Option>()
.HasMany(option => option.Conferences)
.WithRequired(conference => conference.Option)
.HasForeignKey(conference => conference.UserId);
您是否要实现用户与会议之间的1:1关系? 如果是这样,则需要向用户添加一个Id(键)属性。 请参阅我在下面的代码示例中添加的有关1:1关系的注释。 我建议您进一步评估您的域层,以确保这是您要实现的目标...
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Entity;
namespace Stackoverflow
{
public class EntityContext : DbContext
{
public IDbSet<Conference> Conferences { get; set; }
public IDbSet<Option> Options { get; set; }
public IDbSet<User> Users { get; set; }
}
public class Option
{
public int Id { get; set; }
public string Name { get; set; }
public virtual ICollection<Conference> Conference { set; get; }
}
public class Conference
{
// In one-to-one relation one end must be principal and second end must be dependent.
// User is the one which will be inserted first and which can exist without the dependent one.
// Conference end is the one which must be inserted after the principal because it has foreign key to the principal.
[Key, ForeignKey("User")]
public int UserId { get; set; }
public int OptionId { get; set; }
public virtual Option Option { set; get; }
public virtual User User { get; set; }
}
public class User
{
// user requires a key
public int Id { get; set; }
public string Name { get; set; }
public virtual Conference Conference { get; set; }
}
class Program
{
static void Main(string[] args)
{
using (var entityContext = new EntityContext())
{
// added to facilitate your example
var newOption = new Option {Name = "SomeOptionName"};
entityContext.Options.Add(newOption);
entityContext.SaveChanges();
var option = entityContext.Options.Find(newOption.Id);
var user = new User
{
Name = "Name",
Conference = new Conference
{
Option = option
}
};
// need to add the user
entityContext.Users.Add(user);
//...
entityContext.SaveChanges();
}
}
}
}
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