TPC 继承 1 个基类，继承 2 个子项，计算 1 个类属性，未计算其他类属性

Question

我正在开发一个有两个类和一个基类的项目。基类拥有 Projects 和 Programs 模型之间的所有公共属性。项目通过 ProgramID 列与 Programs 相关联。Projects 有一个 ProgramID 的可编辑字段，让用户选择他们想要将项目关联到的程序（并非所有项目都有程序，这就是它可以为空的原因）。

本质上，我希望项目能够读取和写入数据库，而程序只能读取（未设置）。这可以通过 TPC 继承实现吗？欢迎任何建议。如果需要更多信息，我很乐意提供。预先感谢您的帮助！

基类

public abstract class PMBase

{

    [Key]

    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]

    public virtual int ProjectID { get; set; }

    public virtual int? ProgramID { get; set; }

    public virtual Program Program { get; set; }

    //Omitted rest of Model

}

程序类

public class Program : PMBase

{

    [Column("PMGroupID")]

    [DatabaseGenerated(DatabaseGeneratedOption.Computed)]

    public override int? ProgramID { get { return ProjectID; } set { value = null; } }

    //NOTE: Database column names were from legacy changes.  I wish we could change this, but we do not have time.

    [Column("ProgramID")]

    public override int ProjectID { get; set; }

    public virtual ICollection<PMBase> Projects { get; set; }

    //Omitted rest of Model

}

项目类

public class Project : PMBase

{

    [Display(Name = "Program Number & Name")]

    [DatabaseGenerated(DatabaseGeneratedOption.None)]

    public override int? ProgramID { get; set; }

    //Omitted rest of Model

}

数据库上下文映射

modelBuilder.Entity<Project>()

  .Map(prj =>

  {

    prj.MapInheritedProperties();

    prj.ToTable("Projects");

  });

modelBuilder.Entity<Program>()

  .Map(pgm =>

  {

    pgm.MapInheritedProperties();

    pgm.ToTable("Programs");

  });

modelBuilder.Entity<PMBase>()

  .HasOptional(prj => prj.Program)

  .WithMany(pgm => pgm.Projects)

  .HasForeignKey(prj => prj.ProgramID);

看到的错误消息

在尝试各种事情时会看到这些错误。当我看到UNION错误时，我觉得我很接近，但似乎无法克服它。

无法修改列 \"PMGroupID\"，因为它是计算列或 UNION 运算符的结果。

覆盖外键组件“ProgramID”不是类型“Project”上的声明属性。验证它没有被明确地从模型中排除并且它是一个有效的原始属性。

无法确定相关操作的有效顺序。由于外键约束、模型要求或存储生成的值，可能存在依赖性。

Answer 1

在采纳了 Rattles 的建议后，我能够让模型按预期工作。通过创建一个抽象的 getter，我能够成功地将它用作我搜索函数的一个属性。通过 getter 只读取具体属性，它使模型更易于使用/维护。然后我只能在 Project 中使用 ProgramID 属性。谢谢拉特的建议！基类public abstract class PMBase{&nbsp; &nbsp; [Key]&nbsp; &nbsp; [DatabaseGenerated(DatabaseGeneratedOption.Identity)]&nbsp; &nbsp; public virtual int ProjectID { get; set; }&nbsp; &nbsp; [NotMapped]&nbsp; &nbsp; public virtual int? PMGroupID { get { return ProgramIDGetter(); } }&nbsp; &nbsp; public abstract int? ProgramIDGetter();//Omitted rest of Model}程序类public class Program : PMBase{&nbsp; &nbsp; public override int? ProgramIDGetter()&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; return this.ProjectID;&nbsp; &nbsp; }&nbsp; &nbsp; //NOTE: Database column names were from legacy changes.&nbsp; I wish we could change this, but we do not have time.&nbsp; &nbsp; [Column("ProgramID")]&nbsp; &nbsp; public override int ProjectID { get; set; }&nbsp; &nbsp; public virtual ICollection<Project> Projects { get; set; }&nbsp; &nbsp; //Omitted rest of Model}项目类public class Project : PMBase{&nbsp; &nbsp; public override int? ProgramIDGetter()&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; return this.ProgramID;&nbsp; &nbsp; }&nbsp; &nbsp; [Display(Name = "Program Number & Name")]&nbsp; &nbsp; public override int? ProgramID { get; set; }&nbsp; &nbsp; //Omitted rest of Model}数据库上下文映射modelBuilder.Entity<Project>()&nbsp; .Map(prj =>&nbsp; {&nbsp; &nbsp; prj.MapInheritedProperties();&nbsp; &nbsp; prj.ToTable("Projects");&nbsp; });modelBuilder.Entity<Program>()&nbsp; .Map(pgm =>&nbsp; {&nbsp; &nbsp; pgm.MapInheritedProperties();&nbsp; &nbsp; pgm.ToTable("Programs");&nbsp; });modelBuilder.Entity<Project>()&nbsp; .HasOptional(prj => prj.Program)&nbsp; .WithMany(pgm => pgm.Projects)&nbsp; .HasForeignKey(prj => prj.ProgramID);