如何在此特定场景中执行有效的Order By

本文关键字：执行 有效 By Order | 更新日期: 2023-09-27 18:17:36

所以我写这个查询，它工作得很好:

(from schools in context.Schools
                           // some kind of fancy joins
                           select new SomeLocalDTO()
                           {
                               SchoolId = schools.SchoolId,
                               FancySchoolName = schools.SchoolId + "**** -*****  " + schools.SchoolName
                            })
                        .AsQueryable();
/// I have some fancy code here which will aslso take care of take/skip.
// I WANT TO DO ORDER BY HERE, after the skip and take

问题是我想在完成所有花哨的代码后进行排序/跳过。但问题是我没有学校名称在选择语句，而是我有什么是fanyschoolname。我该怎么办?

注1:我不能改变someelocaldto，以在select中包含schoolname。
注2:根据我的业务需求，我不关心我从ABCDEF得到的结果是ABC还是FED。注3:我知道这是一个奇怪的要求，只是这是一个奇怪的业务要求。

如何在此特定场景中执行有效的Order By

你可以创建一个SomeLocalDTO的子类，它确实包括SchoolName，让你的LINQ创建这些对象，然后当你返回到调用者时，只是向下cast到SomeLocalDTO。

更新:

根据你所说的一切，我仍然是这样理解你想要什么…在初始查询之后的order/Take/Skip，但仍按SchoolName排序: 
public class MyDTO: SomeLocalDTO
{
   public string SchoolName {get;set;}
}
var result = (from schools in context.Schools
                           // some kind of fancy joins
                           select new MyDTO()
                           {
                               SchoolId = schools.SchoolId,
                               FancySchoolName = schools.SchoolId + "**** -*****  " + schools.SchoolName,
                               SchoolName = schools.SchoolName    
                            });
return result.OrderBy(s => s.SchoolName)
             .Skip(...)
             .Take(...)
             .Cast<SomeLocalDTO>();

这是一个非常奇怪的请求来排序，做/跳过，然后是不同的排序，但是:

var something=(from schools in context.Schools
  // some kind of fancy joins
  orderby schools.Name
  select schools);
// take/skip
var result=something.OrderBy(...).Select(schools=>
  new SomeLocalDTO()
  {
    SchoolId = schools.SchoolId,
    FancySchoolName = schools.SchoolId + "**** -*****  " + schools.SchoolName
  });

根据你的困惑，我怀疑这就是你想要的:

var something=context.Schools
  .OrderBy(schools=>schools.SchoolName)
  .Skip(...)
  .Take(...)
  .Select(schools=>
    new SomeLocalDTO()
    {
      SchoolId = schools.SchoolId,
      FancySchoolName = schools.SchoolId + "**** -*****  " + schools.SchoolName
    });
相关文章：