我正在開發(fā)一個(gè)有兩個(gè)類和一個(gè)基類的項(xiàng)目?；悡碛?Projects 和 Programs 模型之間的所有公共屬性。項(xiàng)目通過 ProgramID 列與 Programs 相關(guān)聯(lián)。Projects 有一個(gè) ProgramID 的可編輯字段，讓用戶選擇他們想要將項(xiàng)目關(guān)聯(lián)到的程序（并非所有項(xiàng)目都有程序，這就是它可以為空的原因）。本質(zhì)上，我希望項(xiàng)目能夠讀取和寫入數(shù)據(jù)庫，而程序只能讀?。ㄎ丛O(shè)置）。這可以通過 TPC 繼承實(shí)現(xiàn)嗎？歡迎任何建議。如果需要更多信息，我很樂意提供。預(yù)先感謝您的幫助！基類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}程序類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}項(xiàng)目類public class Project : PMBase{ [Display(Name = "Program Number & Name")] [DatabaseGenerated(DatabaseGeneratedOption.None)] public override int? ProgramID { get; set; } //Omitted rest of Model}數(shù)據(jù)庫上下文映射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);看到的錯(cuò)誤消息在嘗試各種事情時(shí)會(huì)看到這些錯(cuò)誤。當(dāng)我看到UNION錯(cuò)誤時(shí)，我覺得我很接近，但似乎無法克服它。無法修改列 \"PMGroupID\"，因?yàn)樗怯?jì)算列或 UNION 運(yùn)算符的結(jié)果。覆蓋外鍵組件“ProgramID”不是類型“Project”上的聲明屬性。驗(yàn)證它沒有被明確地從模型中排除并且它是一個(gè)有效的原始屬性。無法確定相關(guān)操作的有效順序。由于外鍵約束、模型要求或存儲(chǔ)生成的值，可能存在依賴性。
1 回答
慕田峪9158850
TA貢獻(xiàn)1794條經(jīng)驗(yàn) 獲得超8個(gè)贊
在采納了 Rattles 的建議后，我能夠讓模型按預(yù)期工作。
通過創(chuàng)建一個(gè)抽象的 getter，我能夠成功地將它用作我搜索函數(shù)的一個(gè)屬性。通過 getter 只讀取具體屬性，它使模型更易于使用/維護(hù)。然后我只能在 Project 中使用 ProgramID 屬性。謝謝拉特的建議！
基類
public abstract class PMBase
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public virtual int ProjectID { get; set; }
[NotMapped]
public virtual int? PMGroupID { get { return ProgramIDGetter(); } }
public abstract int? ProgramIDGetter();
//Omitted rest of Model
}
程序類
public class Program : PMBase
{
public override int? ProgramIDGetter()
{
return this.ProjectID;
}
//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<Project> Projects { get; set; }
//Omitted rest of Model
}
項(xiàng)目類
public class Project : PMBase
{
public override int? ProgramIDGetter()
{
return this.ProgramID;
}
[Display(Name = "Program Number & Name")]
public override int? ProgramID { get; set; }
//Omitted rest of Model
}
數(shù)據(jù)庫上下文映射
modelBuilder.Entity<Project>()
.Map(prj =>
{
prj.MapInheritedProperties();
prj.ToTable("Projects");
});
modelBuilder.Entity<Program>()
.Map(pgm =>
{
pgm.MapInheritedProperties();
pgm.ToTable("Programs");
});
modelBuilder.Entity<Project>()
.HasOptional(prj => prj.Program)
.WithMany(pgm => pgm.Projects)
.HasForeignKey(prj => prj.ProgramID);
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