EF6 一对一或零关系（Fluent API）

Question

我有这样的类（简化）：

public class Transaction
{
    public int LocalId { get; set; }
    public int MachineId { get; set; }
    public virtual Machine Machine { get; set; }       
    public int? MoneyId { get; set; }
    public virtual TransactionMoney Money { get; set; }
}

public class Machine
{
    public int Id { get; set; }
    public string Name { get; set; }
}

public class TransactionMoney
{
    public int LocalId { get; set; }
    public int MachineId { get; set; }
    public virtual Machine Machine { get; set; }
    public int TransactionId { get; set; }
    public virtual Transaction Transaction { get; set; }
}

我想建立关系 Transaction 1 0...1 TransactionMoney，其中 Money 中的外键应该是 TransactionId 和 MachineId（连接到交易的 LocalId 和 MachineId）。我需要在 fluent API 中执行此操作。

我试过的是：

    modelBuilder.Entity<Transaction>()
                .HasOptional(t => t.Money)
                .WithRequired(t => t.Transaction)
                .HasForeignKey() <--- there is no such method

在另一边

modelBuilder.Entity<TransactionMoney>()
    .HasRequired(t => t.Transaction)
    .WithOptional(t => t.Money)
            .HasForeignKey() <--- there is no such method

Answer 1

你可以用这样的东西

modelBuilder.Entity<TransactionMoney>()
    .HasRequired(t => t.Transaction)
    .WithOptional(t => t.Money)
    .Map(a => a.MapKey("TransactionId", "MachineId"));

事实证明，您所针对的设计无法在 EF 中完成。我能够得到的最接近如下。但在我去之前，有一些事情需要注意。 MoneyId 字段已从 Transaction 中删除。 LocalId 字段已从 TransactionMoney 中删除。外键是用数据注释指定的。如果其中任何一个不可接受，请跳过其余部分。

实体：

public class Transaction
{
    public int LocalId { get; set; }
    public int MachineId { get; set; }
    public virtual Machine Machine { get; set; }
    public virtual TransactionMoney Money { get; set; }
}

public class Machine
{
    public int Id { get; set; }
    public string Name { get; set; }
    public virtual ICollection<Transaction> Transactions { get; set; }
    public virtual ICollection<TransactionMoney> Money { get; set; }
}

public class TransactionMoney
{
    public int MachineId { get; set; }
    public virtual Machine Machine { get; set; }
    public int TransactionId { get; set; }
    [ForeignKey("TransactionId,MachineId")]
    public virtual Transaction Transaction { get; set; }
}

配置

modelBuilder.Entity<Transaction>()
    .HasKey(t => new { t.LocalId, t.MachineId })
    .HasRequired(t => t.Machine)
    .WithMany(t => t.Transactions)
    .HasForeignKey(t => t.MachineId);

modelBuilder.Entity<TransactionMoney>()
    .HasRequired(t => t.Machine)
    .WithMany(t => t.Money)
    .HasForeignKey(t => t.MachineId);

modelBuilder.Entity<TransactionMoney>()
    .HasKey(t => new { t.TransactionId, t.MachineId })
    .HasRequired(t => t.Transaction)
    .WithOptional(t => t.Money);