具有许多一对零或一关系的实体框架

Question

我想在一个实体中实现许多一对零或一对一的关系，但是我在让它工作然后为它生成迁移时遇到了问题。

public class Invoice
{
    public int Id { get; set; }
    public int? MorningExpenseId { get; set; }
    public int? EveningExpenseId { get; set; }
    public Expense MorningExpense { get; set; }
    public Expense EveningExpense { get; set; }
}

public class Expense
{
    public int Id { get; set; }
    public int InvoiceId { get; set; }
    public Invoice Invoice { get; set; }
}
modelBuilder.Entity<Invoice>()
    .HasOptional<Expense>(p => p.MorningExpense)
    .WithRequired(g => g.Invoice);

modelBuilder.Entity<Invoice>()
    .HasOptional<Expense>(p => p.EveningExpense)
    .WithRequired(g => g.Invoice);

但我收到Schema specified is not valid. Errors: The relationship '...' was not loaded because the type '...' is not available. 的错误。 我还尝试在“费用”类中使用主复合键，例如：

public enum ExpenseType { Morning, Evening };
public class Expense
{
    public int Id { get; set; }
    public ExpenseType ExpenseType { get; set; }
    public Invoice Invoice { get; set; }
}

但是让它工作也没有运气。这应该如何使用 Fluent API 来实现？

Answer 1

在实体框架中，应用程序类型必须与数据库类型匹配。关系必须具有虚拟键。

你必须这样编码

public class Invoice
{
    public int Id { get; set; }
    public int MorningExpenseId { get; set; }
    public int EveningExpenseId { get; set; }
    public virtual Expense MorningExpense { get; set; }
    public virtual Expense EveningExpense { get; set; }
}

public class Expense
{
    public int Id { get; set; }
    public int InvoiceId { get; set; }
    public virtual Invoice Invoice { get; set; }
}