I've been trying to figure out how to translate the following LINQ query syntax to method syntax, but I just don't get it:

from exa in _context.Exams
from stu in exa.Class.Students
where exa.Id == 1
select new StudentFullName
{
    Id = stu.Id,
    FullName = stu.Person.FirstName   " "   stu.Person.LastName
}

The property ICollection<Student> Students from the table Classes for the many-to-many relationship with Students is causing my confusion.

I tried this:

_context.Exams
.Where(exa => exa.Id == id)
.Select(exa => new StudentFullName
{
    Id = exa.Class.Students.Select(stu => stu.Id),
    FullNamee = exa.Class.Students.Select(stu => stu.Person.FirstName   " "   stu.Person.LastName)
}).ToList();

But I can't create the class StudentFullName because the query returns IEnumerable<int> instead of int for each property.

That's what I get: https://imgur.com/a/Tp5hPHE

That's what I should get: https://imgur.com/a/PyWYQh5

EDIT: Tweaked the solution from tymtam and it worked

_context.Exams
.Where(exa => exa.Id == id)
.SelectMany(exa => exa.Class.Students
  .Select(stu => new StudentFullNameViewModel
  {
      Id = stu.Id,
      FullName = stu.Person.FirstName   " "   stu.Person.LastName
  })
).ToList()

CodePudding user response：

It's very suspicious that:

1. there is no join between students and exams
2. exa is not used in the result object

A 1-to-1 translation is I think this:

var students2 = exams
  .Where(exa => exa.Id == id)
  .SelectMany(exa => exa.Class.Students
    .Select(stu => new StudentFullName
    {
        Id = stu.Id,
        FullNamee = stu.Person.FirstName   " "   stu.Person.LastName
    }))
  .ToList();