实体框架代码优先隐含复合键上的可选一对多关系

Question

更新：在 GitHub 上创建了 sample project。

在我现有的数据库中，我有一个没有键的通用审计表，但我想先用 EF 代码插入到这个审计表中。

现有报告根据 AffectedId 和 EntityId 提取审计，其中 EntityId 在很多地方被硬编码。
我对数据库进行了逆向工程，但这些表之间没有明确的关系......所以这里是基本 POCO 对象（我也无法建立关系，它是一个现有系统）

public class Audit
{
    public int Id { get; set; }
    public int EntityId { get; set; }
    public string AffectedId { get; set; }       
    public string NewValue { get; set; }
}

public class Action1
{
    public int Id { get; set; }
    public string Desc { get; set; }
}   

public class Action2
{
    public int Id { get; set; }
    public string Desc { get; set; }
}

我想我希望 POCO 对象看起来像这样

public class Audit
{
    public int Id { get; set; }
    public int EntityId { get; set; }
    public string AffectedId { get; set; }       
    public string NewValue { get; set; }
    public virtual Action1 Action1 { get; set; } // but I don't want this to change audit table
    public virtual Action2 Action2 { get; set; } // but I don't want this to change audit table
}

public class Action1
{
    public Action1() {this.Audits = new List<Audit>();}
    public int Id { get; set; }
    public string Desc { get; set; }
    public virtual ICollection<Audit> Audits { get; set; }
}   

public class Action2
{
    public Action2() {this.Audits = new List<Audit>();}
    public int Id { get; set; }
    public string Desc { get; set; }
    public virtual ICollection<Audit> Audits { get; set; }
}

但我似乎无法获得流畅的映射以允许我在审核中插入已填充 AffectedId 的操作（1 或 2）。这就是我在映射对象上的想法，但似乎无法让硬编码的 EntityId 键正常工作。

public class AuditMap : EntityTypeConfiguration<Audit>
{
    public AuditMap()
    {
        // Primary Key
        this.HasKey(t => t.Id);


        this.HasOptional(t => t.Action1)
            .WithMany(t => t.Audits)
            .HasForeignKey(t => new {EntityId = 3, AffectedId = t.Id});

        this.HasOptional(t => t.Action2)
            .WithMany(t => t.Audits)
            .HasForeignKey(t => new {EntityId = 5, AffectedId = t.Id});
    }
}

public class Action1 : EntityTypeConfiguration<Action1>
{
    public Action1Map()
    {
        // Primary Key
        this.HasKey(t => t.Id);
    }
}

public class Action2 : EntityTypeConfiguration<Action2>
{
    public Action2Map()
    {
        // Primary Key
        this.HasKey(t => t.Id);
    }
}

任何关于如何更改 C# 而不是 SQL 的建议将不胜感激。

Answer 1

映射不会处理这种情况，但您可以修改您的域模型和业务规则来执行此操作。并且为 EntityId 的魔法值设置一个枚举会更好。

public class Audit
{
    public int Id { get; set; }
    public int EntityId { get; set; }
    public string AffectedId { get; set; }       
    public string NewValue { get; set; }
}

public abstract class AuditableAction{

    public AuditableAction() {this.Audits = new List<Audit>();}

    public int Id { get; set; }
    public string Desc { get; set; }
    public virtual IList<Audit> Audits { get; set; }

    public void Audit(string description){
        this.Audits.Add(new Audit(){
            EntityId = this.GetEntityId(),
            AffectedId = this.Id,
            NewValue = description
        });
    }

    public abstract int GetEntityId();
}

public class Action1 : AuditableAction
{
    public override int GetEntityId(){
        return AuditCode.Magic3.GetHashCode();
    }
}   

public class Action2 : AuditableAction
{
    public override int GetEntityId(){
        return AuditCode.Magic5.GetHashCode();
    }
}

public enum AuditCode{
    Magic3 = 3,
    Magic5 = 5
}

基于GitHub代码转储使用

using (var context = new yunoworkContext())
{
    var a = new Action1() {Id = 4, Desc = Guid.NewGuid().ToString()};

    // This audit should insert an audit with EntityId = 3 and AffectedId = {primary key of the assiciated Action1}
    a.Audit("Console!");
    context.SaveChanges();
}