如何在實體框架6中使用Fluent API來映射沒有外鍵屬性的一對多對象列表？

Question

我有以下的類（即我不能更新，添加屬性或添加註釋）：

public class ApprovalRuleset 
{ 
    public Guid Id { get; set; } 
    public List<ApprovalRule> ApprovalRules { get; protected internal set; } 
} 

public class ApprovalRule 
{ 
    public Guid Id { get; set; } 
    public string Value { get; protected internal set; } 
} 

我嘗試寫一些流利的API代碼與實體框架6將它們映射到兩張桌子。

這是ApprovalRule配置：

public class ApprovalRuleEntityConfiguration : EntityTypeConfiguration<ApprovalRule> 
{ 
    public ApprovalRuleEntityConfiguration() 
    { 
     HasKey(x => x.Id); 
     Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity); 
     Property(x => x.Value).IsRequired().HasMaxLength(450); 
    } 
} 

到目前爲止我有：

public class ApprovalRulesetEntityConfiguration : EntityTypeConfiguration<ApprovalRuleset> 
{ 
    public ApprovalRulesetEntityConfiguration() 
    { 
     HasKey(x => x.Id); 
     Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity); 
     HasMany(x => x.ApprovalRules); 
    } 
} 

上表的外鍵 'ApprovalRules' 的列 'ApprovalRuleset_Id' 不能因爲主鍵 列無法確定而創建。使用AddForeignKey fluent API至 完全指定外鍵。

public class ApprovalRulesetEntityConfiguration : EntityTypeConfiguration<ApprovalRuleset> 
{ 
    public ApprovalRulesetEntityConfiguration() 
    { 
     HasKey(x => x.Id); 
     Property(x => x.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity); 
     HasRequired(x => x.ApprovalRules) 
      .WithMany() 
      .HasForeignKey(x => x.Id); 
    } 
} 

多重衝突與在關係 「ApprovalRuleset_ApprovalRules的角色 'ApprovalRuleset_ApprovalRules_Target' 的引用約束。由於 從屬角色中的所有屬性都是不可空的，因此主體角色 的多重性必須爲'1'。

我錯過了什麼？我花了很多年尋找堆棧溢出和谷歌。

Answer 1

您需要在ApprovalRule類中添加兩個屬性。然後映射會是這樣 -

public class ApprovalRuleset 
{ 
    public Guid Id { get; set; } 
    public List<ApprovalRule> ApprovalRules { get; protected internal set; } 
} 

public class ApprovalRule 
{ 
    public Guid Id { get; set; } 
    public string Value { get; protected internal set; } 

    public int ApprovalRulesetId { get; set; } 
    public virtual ApprovalRuleset ApprovalRuleset { get; set; } 
} 

public class ApprovalRulesetEntityConfiguration : EntityTypeConfiguration<ApprovalRuleset> 
{ 
    public ApprovalRulesetEntityConfiguration() 
    { 
     HasKey(t => t.Id); 
    } 
} 

public class ApprovalRuleEntityConfiguration : EntityTypeConfiguration<ApprovalRule> 
{ 
    public ApprovalRuleEntityConfiguration() 
    { 
     HasKey(t => t.Id); 

     /*Property(t => t.Value) 
      .HasMaxLength(100);*/ 

     HasRequired(t => t.ApprovalRuleset) 
      .WithMany(t => t.ApprovalRules) 
      .HasForeignKey(d => d.ApprovalRulesetId); 
    } 
}