Question

在我的数据库模型中，我向表中添加了第二列，该表之前已经有一个链接到同一个表。我的更改之前的模型如下所示：

[Table("RepairProcesses", Schema = "Data")]    
public class RepairProcess : DatabaseBase
{
    [DataMember]
    [Column("SerialNumberID")]
    public Guid SerialNumberID { get; set; }

    [ForeignKey("SerialNumberID")]
    public virtual SerialNumber SerialNumber { get; set; }
}

现在我将第二个链接添加到表中，模型现在看起来如下：

[Table("RepairProcesses", Schema = "Data")]    
public class RepairProcess : DatabaseBase
{
    [DataMember]
    [Column("SerialNumberID")]
    public Guid SerialNumberID { get; set; }

    [DataMember]
    [Column("ReplacementSerialNumberID")]
    public Guid? ReplacementSerialNumberID { get; set; }

    [ForeignKey("SerialNumberID")]
    public virtual SerialNumber SerialNumber { get; set; }

    [ForeignKey("ReplacementSerialNumberID")]
    public virtual SerialNumber ReplacementSerialNumber { get; set; }
}

当我现在尝试创建迁移脚本时，EntityFramework会删除foreingn键并创建一个名为SerialNumber_ID的新列。

    public override void Up()
    {
        DropForeignKey("Data.RepairProcesses", "SerialNumberID", "Data.SerialNumbers");
        AddColumn("Data.RepairProcesses", "SerialNumber_ID", c => c.Guid());
        AddColumn("Data.RepairProcesses", "ReplacementSerialNumberID", c => c.Guid());
        CreateIndex("Data.RepairProcesses", "SerialNumber_ID");
        CreateIndex("Data.RepairProcesses", "ReplacementSerialNumberID");
        AddForeignKey("Data.RepairProcesses", "ReplacementSerialNumberID", "Data.SerialNumbers", "ID");
        AddForeignKey("Data.RepairProcesses", "SerialNumber_ID", "Data.SerialNumbers", "ID");
    }

    public override void Down()
    {
        DropForeignKey("Data.RepairProcesses", "SerialNumber_ID", "Data.SerialNumbers");
        DropForeignKey("Data.RepairProcesses", "ReplacementSerialNumberID", "Data.SerialNumbers");
        DropIndex("Data.RepairProcesses", new[] { "ReplacementSerialNumberID" });
        DropIndex("Data.RepairProcesses", new[] { "SerialNumber_ID" });
        DropColumn("Data.RepairProcesses", "ReplacementSerialNumberID");
        DropColumn("Data.RepairProcesses", "SerialNumber_ID");
        AddForeignKey("Data.RepairProcesses", "SerialNumberID", "Data.SerialNumbers", "ID");
    }

问题是这是一个高效的数据库，当EF为SerialNumber创建一个新的字段时，我丢失了指向正确字段的链接。

当我只删除创建新列的向上/向下脚本中的行时，我遇到了问题，因为EF期望名为SerialNumber_ID的列。

感谢您的帮助，迈克尔

Answer 1

尝试以这种方式更改SerialNumber课程：

public class SerialNumber 
{
    //other stuff....

    [InverseProperty("SerialNumber")]
    public virtual ICollection<RepairProcess> SerialNumbers {get;set;}

    [InverseProperty("ReplacementSerialNumber")]
    public virtual ICollection<RepairProcess> ReplacementSerialNumbers {get;set;}
}

c＃EntityFramework CodeFirst迁移为现有列创建新列

1 个答案: