CODEWITHSUNDEEP
c#generics
Ray Suelzer
Ray Suelzer

Reputation: 4107

Using Generic Type T in a class property

In c#, how would I go about setting up a class that can return another class (of any type).

For example:

public class DataResponse {

public bool Success {get;set;}
public string ResponseMessage {get;set;}
public T Data {get;set;}

}

T should be any type of class.

var personData = new PersonClass() {
           FirstName= "John",
           LastName="Doe"
          };


var response = new DataResponse<EmployeeClass>() {
Success = true;
ResponseMessage = "OK";
Data = personData
}

then I can go and get

response.Data.FirstName

The data proprety will be of a changing class it could be a person or an employer for example.

Any help would be appreciated.

Upvotes: 0

Views: 434

Answers (4)

knightro
knightro

Reputation: 1

Make your class generic, as suggested by Sergey Berezovskiy and p.s.w.g. Additionally, you could require that T be of a type that implements FirstName and LastName:

public interface INamable
{
    string FirstName { get; set; }
    string LastName { get; set; }
}

public class DataReponse<T> where T : INamable
{
    public bool Success { get; set; }
    public string ResponseMessage { get; set; }
    public T Data { get; set; }
}

Upvotes: 0

Sergey Berezovskiy
Sergey Berezovskiy

Reputation: 236318

Make your class generic:

public class DataResponse<T> // class is parametrized with T
{
    public bool Success {get;set;}
    public string ResponseMessage {get;set;}
    public T Data {get;set;}
}

Now your code will work - create class parametrized with some specific type and Data property will have that type:

var response = new DataResponse<EmployeeClass> {
                  Success = true;
                  ResponseMessage = "OK";
                  Data = personData
               };

NOTE: I like to create extension methods which create response objects based on data I have:

public static DataResponse<T> ToSuccessResult<T>(this T data)
{
    return new DataResponse<T> {
                  Success = true;
                  ResponseMessage = "OK";
                  Data = data
               };
}

Now type of T can be inferred from your data type and response creation will look like:

var response = personData.ToSuccessResult();

Upvotes: 6

David Heffernan
David Heffernan

Reputation: 613451

Only methods and types can be generic. Which means that you cannot declare a generic property. The best you can do is make the class that contains the property generic.

public class DataResponse<T>
{
    public T Data { get; set; }
}

Upvotes: 2

p.s.w.g
p.s.w.g

Reputation: 149050

You need to declare the generic type parameter at the class level:

public class DataResponse<T> // <-- here
{
    public bool Success {get;set;}
    public string ResponseMessage {get;set;}
    public T Data {get;set;}
}

So now, as long as EmployeeClass has a property named FirstName, this will work:

var personData = new PersonClass() {
    FirstName = "John",
    LastName = "Doe"
};

var response = new DataResponse<EmployeeClass>() {
    Success = true;
    ResponseMessage = "OK";
    Data = personData
};
Console.WriteLine(response.Data.FirstName); // John

Upvotes: 3

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