Question

对于TestType，我想包括导航道具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，这很有效：

我将TestType包括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的，有两个.Include（t =＆gt; 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();

如果在SQL事件探查器中看到查询结果，则查询是您假装的，而不重复包含到TestType（仅与该表连接1次）

你有另一种方法可以做到这一点，但我更喜欢以前的方式！

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

Answer 2

如果这种类型的包含在您的代码库中很常见，那么创建几个扩展方法可能是有用的：

test 1 false + test 2 false: case 1 -- no user interaction available
test 1  true + test 2 false: case 2 -- interact via XWindows
test 1 false + test 2  true: case 3 -- interact via STDIN/console
test 1  true + test 2  true: case 4 -- XWindows or STDIN/console, whichever is preferred

通过此操作，您可以将查询更改为

"sort": {
  "_script" : {
    "script" : {
     "source" : "params._source.participants[0].participantEmail.toLowerCase()",
     "lang" : "painless"
   },
   "type" : "string",
   "order" : "desc"
 }

尽管这不支持深度超过2个级别。

Answer 3

为什么不两次使用Include？

  var myVar= ((MyContext) _context)
            .MasterEntity
            .Include(x => x.FirstChild)
            .Include(x=>x.FirstChild.FirstGrandChild)
            .Include(x=>x.FirstChild.SecondGrandChild)
            .Where(x => x.Id== input)
            .ToList();

如何在One Include之后执行多个ThenInclude导航道具

3 个答案: