c# - 如何在一个 Include 之后执行多个 ThenIninclude 导航 Prop

Question

对于 TestType，我想包含导航 Prop Schoolclass 和 subject。

我可以做:

.Include(t => t.TestType)
 .ThenInclude(x => x.Subject)

但不是:

.Include(t => t.TestType)
.ThenInclude(x => x.Subject)
.ThenInclude(x => x.Schoolclass)

因此我尝试了一个小技巧并且成功了:

我包含了 TestType 2 次...

var test = await context.Tests.Where(t => t.SchoolyearId == schoolyearId)
                                          .Include(t => t.TestType)
                                          .ThenInclude(x => x.Subject)
                                           .Include(t => t.TestType)
                                          .ThenInclude(x => x.Schoolclass)
                                           .AsNoTracking()
                                          .ToListAsync();

这是官方方法还是有更好的方法？

更新

   public class TestType
    {
        public TestType()
        {
            Tests = new HashSet<Test>();
        }

        public int Id { get; set; }
        public string Name { get; set; }
        public int Weight { get; set; }
        public ISet<Test> Tests { get; set; }
        public Schoolyear Schoolyear { get; set; }  
        public Schoolclass Schoolclass { get; set; }   
        public Subject Subject { get; set; }
        public int SchoolyearId { get; set; }
    }

Answer 1

最好的方法是你之前写，用两个.Include(t => t.TestType)

var test = await context.Tests.Where(t => t.SchoolyearId == schoolyearId)
                                      .Include(t => t.TestType)
                                      .ThenInclude(x => x.Subject)
                                       .Include(t => t.TestType)
                                      .ThenInclude(x => x.Schoolclass)
                                       .AsNoTracking()
                                      .ToListAsync();

如果您在 SQL Profiler 中看到查询结果，则该查询是您假装的，没有重复包含到 TestType(仅与该表有 1 个联接)

你还有另一种方法可以做到这一点，但我更喜欢以前的方法!

.Include("TestType.Subject") 
.Include("TestType.Schoolclass")