how to return multiple items from linq query - linq

Question

Hi I have a method which i am calling to get the list of email of users , i am returning that list and my calling method is using these emails , I want to get the program title as well to pass with the list how to achieve that.
public static List<string> GetAllStudents(int? year,int? program,int? module,int? block)
{
var res = (from s in std.Student_courses
join p in std.Programs
on s.Program_Id equals p.Id
join sc in std.Students
on s.Student_id equals sc.Student_Id
where s.Program_Id == program && s.Year_Id == year && s.Module_Id==module && s.Block_Id==block
select new
{
Email = sc.Student_Email,
Program=p.Program_Title
}).ToList();
List<string> EmailList = new List<string>();
foreach (var item in res)
{
EmailList.Add(item.Email);
}
return EmailList;
//var result = from userDistrict in std.Student_courses
// from district in std.Students
// where (userDistrict.Student_id == district.Student_Id)
// select district.Student_Email;
// return std.Student_courses.Where(x => x.Program_Id == program && x.Year_Id == year && x.Module_Id == module && x.Block_Id == block ).ToList();
}

Answer 1

Using new {} creates an anonymous type which cannot be passed to a method or returned out of the method scope (even if it's inside a list).
You are returning a list of string values. I recommend you change this to a list of a new class that contains both the email and the Program properties.
public class EmailInfo
{
public string Email { get; set; }
public string Program { get; set; }
}
You can then return this class from your method:
public static List<EmailInfo> GetAllStudents(int? year, int? program, int? module, int? block)
{
var results =
from s in std.Student_courses
join p in std.Programs on s.Program_Id equals p.Id
join sc in std.Students on s.Student_id equals sc.Student_Id
where s.Program_Id == program && s.Year_Id == year && s.Module_Id == module && s.Block_Id == block
select new EmailInfo
{
Email = sc.Student_Email,
Program = p.Program_Title
};
return results.ToList();
}
And use both values (as an example I've printed the values to the console):
var emails = GetAllStudents();
emails.ForEach(x => Console.WriteLine($"'{x.Email}', '{x.Program}'"));
This could print the following to the console:
'email1#domain.com', 'title 1'
'email2#domain.com', 'title 2'