实体框架不更新 mySql 中计算键的自动增量字段答案

【问题标题】：Entity Framework does not update an auto-increment field of a computed key in mySql实体框架不更新 mySql 中计算键的自动增量字段
【发布时间】：2013-09-19 21:32:06
【问题描述】：

我正在尝试使用实体框架保存实体，尽管 EF 没有更新自动增量字段

public class Address
{
    public int Id { get; set; }
    public int DatacenterId { get; set; }
    public virtual Datacenter Datacenter { get; set; }
}

public class AddressMapping : EntityTypeConfiguration<Address>
{
    public AddressMapping()
    {
        this.HasKey(k => new { k.Id, k.DatacenterId });
        this.HasRequired(itr => itr.Datacenter)
            .WithMany()
            .HasForeignKey(fk => fk.DatacenterId);

        this.Property(p => p.Id)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
    }
}

using (var context = new MyContext())
{
    var address = new Address(); //Initialize and set all values. Include the FK
    context.Address.Add(address);
    context.SaveChanges();

    //address.Id is still 0
}

我从 mySql 分析了以下命令：

INSERT INTO `address`(
    `Id`, 
    `DatacenterId`, 
)VALUES(
    0, 
    1, 
)

【问题讨论】：

标签： mysql entity-framework ef-code-first

【解决方案1】：

我已经更改了映射命令的顺序并且它正在工作。我不知道 EF 映射命令会改变映射结果。

public class AddressMapping : EntityTypeConfiguration<Address>
{
    public AddressMapping()
    {
        this.Property(p => p.Id)
            .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);

        this.HasKey(k => new { k.Id, k.DatacenterId });

        this.HasRequired(itr => itr.Datacenter)
            .WithMany()
            .HasForeignKey(fk => fk.DatacenterId);
    }
}

最后它生成了正确的sql命令：

INSERT INTO `address`(
    `DatacenterId`, 
)VALUES(
    1, 
);
SELECT
    `Id`
FROM 
    `address`
WHERE  
     row_count() > 0 AND `Id` = last_insert_id() AND `DatacenterId` = 1

【讨论】：