entity-framework - 保存时EF Core OwnsOne失败

Question

我有以下模型:

public class User
{
    public Guid Id {get;set;}
    public string Username {get;set;}
    public string Address Useraddress {get;set;}
}

public class Address
{
    public string Street {get;set;}
    public string Zipcode {get;set;}
}

我想将 Useraddress中的数据保存到同一 User表中。因此，我在上下文生成器中添加了 OwnsOne配置。

class UserEntityTypeConfiguration : IEntityTypeConfiguration<User>
{
    public void Configure(EntityTypeBuilder<User> builder)
    {
        builder.HasKey(x => x.Id);
        builder.OwnsOne(x => x.UserAddress);
    }
}

当我运行迁移工具时，一切似乎都很好。这是生成的迁移脚本的相关部分:

migrationBuilder.CreateTable(
    name: "Users",
    columns: table => new
    {
        Id = table.Column<Guid>(nullable: false),
        Username = table.Column<string>(nullable: false),
        Useraddress_Street = table.Column<string>(nullable: true),
        Useraddress_Zipcode = table.Column<string>(nullable: true)
    },
    constraints: table =>
    {
        table.PrimaryKey("PK_Users", x => x.Id);
    });

然后，当我稍后尝试添加 User时:

await _dbContext.Users.AddAsync(user);
await _dbContext.SaveChangesAsync();

然后，我得到以下错误:

The entity of 'User' is sharing the table 'Users' with 'User.Useraddress#Address', but there is no entity of this type with the same key value that has been marked as 'Added'

我做错了什么吗？

PS。
我正在使用Entity Framework Core 2.0。

Answer 1

由于EF Core 2.0支持表拆分，因此默认情况下EF Core 2.0会为其拥有的实体创建一个主键作为影子属性，因此UserAddress实例中User属性的值不能为null，必须对其进行定义。

var user = new User
{
    Id = Guid.NewGuid(),
    Username = "...",
    UserAddress = new Address
    {
        Street = "...",
        Zipcode = "..."
    }
};

await _dbContext.Users.AddAsync(user);
await _dbContext.SaveChangesAsync();

如果您希望拥有的实体的值为空，则只需定义一个默认实例，即:

var user = new User
{
    Id = Guid.NewGuid(),
    Username = "...",
    UserAddress = new Address()
};

您可以在此处阅读有关拥有实体隐式键的更多信息: https://docs.microsoft.com/en-us/ef/core/modeling/owned-entities#implicit-keys