EF6：为实体配置复杂映射（代码优先）答案

【问题标题】：EF6: Configure complex mapping for entities (code first)EF6：为实体配置复杂映射（代码优先）
【发布时间】：2016-06-16 15:30:40
【问题描述】：

我有两个想要使用 EF6 fluent API 配置的数据库实体。

public class Account
{
    public Int32 Id { get; set; }

    public Int32? LastOperationId { get; set; }
    public virtual Operation LastOperation { get; set; }

    public virtual List<Operation> Operations { get; set; }
}

public class Operation
{
    public Int32 Id { get; set; }

    public Int32? AccountId { get; set; }
    public virtual Account Account { get; set; }
}

对于任何配置，在尝试将帐户实体实例插入数据库时，我总是会收到错误“无法确定相关操作的有效排序”：

var account = new Account();
var operation = new Operation();

account.Operations = new List<Operation>() { operation };
account.LastOperation = operation;

dbContext.Accounts.Add(account);
dbContext.SaveChanges();

【问题讨论】：

标签： c# sql .net entity-framework

【解决方案1】：

幸运的是，EF 推断出外键列 AccountId 和 LastOperationId，所以这对我有用：

modelBuilder.Entity<Operation>()
.HasKey(x => x.Id)
.HasOptional(x => x.Account)
.WithMany(x => x.Operations);

modelBuilder.Entity<Account>()
.HasKey(x => x.Id)
.HasOptional(x => x.LastOperation);

【讨论】：

【解决方案2】：

这正是您在 Code-First 中所需要的组合：

public class Account
{
    // One to one to one relationship (shared PK)
     public int Id { get; set; }

     // One to one to one relationship (shared PK)
     public virtual Operation Operation { get; set; }

    // One to many relationship foreign Key
    [InverseProperty("AccountForList")]
     public virtual List<Operation> Operations { get; set; }
   }

   public class Operation
   {
    // One to one to one relationship (shared PK)
    [ForeignKey("Account")]
     public Int32 Id { get; set; }

     // One to one to one relationship (shared PK)
     public virtual Account Account { get; set; }

     // One to many relationship foreign Key
     public Int32? AccountForListId { get; set; }

     // One to many relationship foreign Key
     [ForeignKey("AccountForListId")]
     public virtual Account AccountForList { get; set; }
     }

帐户表：列名：Id

操作表：列名Id(与Account共享)、AccountForListId(1..n)

【讨论】：