Error using the generic type BaseUser requires 1 argument

Question

I have an interface

public interface  IIdentity<T>
{
    T GetUser();
}

I have a base class that implements the Interface as an abstract method

public abstract class BaseUser<T> : IIdentity<T>
{
    public string UserId { get; set; }
    public string AuthType { get; set; }
    public List<Claim> Claims { get; set; }
    public abstract T GetUser();
}

In the class that inherits the base class

 public class JwtUser : BaseUser
 {
     public string Sub { get; set; }
 }

I get an error using the generic type BaseUser requires 1 argument, what do i do here, basically I'd like my user to inherit shared properties from the base class which it does (i think) and to implement the generic method from the base class as I'm going to have different types of users (JWT/Windows etc) I need to abstract away the getUsers method, hope that makes sense ?

Why do you need `` in interface and base class? – Chetan Mar 18 '18 at 18:29 — Chetan, Mar 18 '18 at 18:29
Interface doesn't know what type of user ? – fuzzybear Mar 18 '18 at 18:33 — fuzzybear, Mar 18 '18 at 18:33

score 3 · Accepted Answer · answered Mar 18 '18 at 18:34

You have to ways to implement this, both require to set the generic in BaseUser.

You could expose that generic:

public class JwtUser<T> : BaseUser<T>
{
    public string Sub { get; set; }
}

Or, just set the generic:

public class JwtUser : BaseUser<JwtUser>
{
    public string Sub { get; set; }
}

Pranay Rana · Answer 2 · 2018-03-18T18:36:12.417

1

it should be like , for Ref : Generic Classes (C# Programming Guide)

public class JwtUser<User> : BaseUser<User>
 {
     public string Sub { get; set; }
 }

or

public class JwtUser<T> : BaseUser<T>
 {
     public string Sub { get; set; }
 }

and when create instace

var jwtUser =new JwtUser<User> ();

or

  class JwtUser: BaseUser<JwtUser> { }

In all way at the end you must need to specify value for T template as its generic.

For example if you take List<T> for using it you must need to intialize with proper type like if interger list then List<int> intlist = new List<int>();

edited Mar 18 '18 at 18:36

answered Mar 18 '18 at 18:31

Pranay Rana

175,020
35
237
263

I don't have a user class the JWTUser needs to inherit from baseUser and make a whole user – fuzzybear Mar 18 '18 at 18:34
1

@saj - but you have to to pass value for T , – Pranay Rana Mar 18 '18 at 18:34
1

@saj - its resolves your issue but i suggest go through generics once again for getting more clear picture... – Pranay Rana Mar 18 '18 at 18:45

Error using the generic type BaseUser requires 1 argument

2 Answers2