我在Entity Framework中使用每层次表(TPH)继承.现在我希望得到一个列表 – 在这个例子中 – 部门可以是子类型.我希望集合中的项目包含自己的自定义属性,而不仅仅是基本模型的属性.
我怎样才能做到这一点？
public class Department
{
public Department()
{
DepartmentType = this.GetType.Name;
}
public int Id {get; set;}
public string DepartmentType {get; set;}
}
public class Finance : Department
{
public virtual Manager Manager {get; set;}
}
public class Sports : Department
{
public virtual Coach Coach {get; set;}
}
// This obvIoUsly crashes instantly
// How can I include Manager if type is Finance and Coach if type is Sports?
context.Departments
.Include(c => (c is Finance) ? c.Manager : null)
.Include(c => (c is Sports) ? c.Coach : null);
我甚至试图返回IEnumerable< object>并为每个子类型添加一个多态方法,如下所示：
public class Sports : Department
{
public Coach Coach {get; set;}
public object Export()
{
return new
{
this.Id,this.DepartmentType,this.Coach
}
}
}
然后做这样的事情：
context.Departments.Select(c => c.Export())
但这也不起作用.
期望的JSON用法
[
{ Id: 1,DepartmentType: "Finance",Manager: { Name: "John" } },{ Id: 2,Manager: { Name: "Harold" } },{ Id: 3,DepartmentType: "Sport",Coach: { Name: "Fred",SportType: "Soccer" } },{ Id: 4,Manager: { Name: "Hank" } },{ Id: 5,Coach: { Name: "Mark",SportType: "Football" } }
]
解决方法
通过这种方式,您可以找到财务和体育部门并包括他们的财产：
var financeDeparments = context.Departments.OfType<Finance>().Include(p => p.Manager).ToList(); var sportDepartments = context.Departments.OfType<Sports>().Include(p => p.Coach).ToList();
