EntityFramework：如何映射零对一关系？

Question

我有以下数据库表：

FundAllocation {below two columns make a composite primary key}
       [CurrencyRefId] (int)  {FK to a table Currency.CurrencyId}
       [AllocationRefId] (int) {FK to Allocation.AllocationId}

Allocation
       [AllocationId] (int) {PK Identity Column}
       [AllocationTitle] (varchar)

以下是与上表对应的实体：

public class FundAllocation
{
    [Key]
    [Column(Order = 1)]
    public int CurrencyRefId { get; set; }
    [Key]
    [Column(Order = 2)]
    public int AllocationRefId { get; set; }

    [ForeignKey("AllocationRefId")]
    public Allocation Allocation { get; set; }
}

public class Allocation
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int AllocationId { get; set; }
    public string AllocationTitle { get; set; }
}

现在，当我从数据上下文中获取FundAllocation列表时，其Allocation属性设置为null。实现这种零对一关系还需要哪些其他配置？

Answer 1

要解决您的问题，您必须通过以下方式填充该属性：

• 启用延迟加载：
  • public virtual Allocation Allocation { get; set; }
• 急切加载：
  • eagerly loading