I have the following method that returns the output of the LINQ query. The method works perfectly fine but I have dynamic as a return type because the following 2 didn't work: List & IEnumerable. What should be the correct return type be for a LINQ query output? My method:
public dynamic GetUserFollowers(Guid user_gd)
{
var listOfFollowers = from users in _context.Users
from userFollowing in _context.UserFollowings.Where(
uf => uf.User2 != users.Gd && uf.User2 == user_gd && uf.User1 == users.Gd
)
select new { users.Gd, users.Firstname, users.Lastname, users.Username, users.Email };
return listOfFollowers;
}
User model:
public class User
{
[Key]
public Guid Gd { get; set; }
public string Firstname { get; set; }
public string Lastname { get; set; }
public string Username { get; set; }
public string Email { get; set; }
public byte[] PasswordHash { get; set; }
public byte[] PasswordSalt { get; set; }
}
Error when using List< User >:
Cannot implicitly convert type 'System.Linq.IQueryable<<anonymous type: System.Guid Gd, string Firstname, string Lastname, string Username, string Email>>' to 'System.Collections.Generic.List<CosialAPI.Authorization.Entities.User>'. An explicit conversion exists (are you missing a cast?)
Error when using IEnumerable< User >:
Cannot implicitly convert type 'System.Linq.IQueryable<<anonymous type: System.Guid Gd, string Firstname, string Lastname, string Username, string Email>>' to 'System.Collections.Generic.IEnumerable<CosialAPI.Authorization.Entities.User>'. An explicit conversion exists (are you missing a cast?)
Help would be appreciated!
Return value for the current code is in the error message:
IQueryable<<anonymous type: System.Guid Gd, string Firstname, string Lastname, string Username, string Email>>
Change this line
select new { users.Gd, users.Firstname, users.Lastname, users.Username, users.Email };
with this one
select new User() { Gd = users.Gd, Firstname = users.Firstname, Lastname = users.Lasname, Username = users.Username };
Then you can change dynamic
with IEnumerable<User>
.
If you want to change the return type to List<User>
, add a ToList()
as @juharr said in the comments.
Another option is to create a new class with only the properties you want to expose. Eg
public class UserDto
{
public Guid Gd { get; set; }
public string Firstname { get; set; }
public string Lastname { get; set; }
public string Username { get; set; }
public string Email { get; set; }
}
then use it in the query
select new UserDto
{
Gd = users.Gd,
Firstname = users.Firstname,
Lastname = users.Lastname,
Username = users.Username,
Email = users.Email
};
and use either .AsEnumerable()
or .ToList()
to get a return type of IEnumerable<UserDto>
or List<UserDto>
.
return listOfFollowers.ToList(); // or .AsEnumerable()
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