No suitable method to override in C#

Question

I have the following method in my code, which takes a Guid as a parameter. I want to override this method with one that takes a string as a parameter:

public class SendEmailApi: ISendEmailApi
{

     public async Task<EmailTemplate> GetTemplateByIdAsync(Guid templateId)
     {
         var response = await _emailClient.RequestAsync(EmailClient.Method.GET, urlPath: $"templates/{templateId}");

         return JsonConvert.DeserializeObject<EmailTemplate>(await response.Body.ReadAsStringAsync());
     }
}

However when I try to implement, I get the error that there is no suitable method to override.

public async override Task<EmailTemplate> GetTemplateByIdAsync(string templateId)
{
     var response = await _emailClient.RequestAsync(EmailClient.Method.GET, urlPath: $"templates/{templateId}");

     return JsonConvert.DeserializeObject<EmailTemplate>(await response.Body.ReadAsStringAsync());
}

The interface looks like this:

public interface ISendEmailApi
{
    Task<EmailTemplate> GetTemplateByIdAsync(Guid templateId);
}

I am relatively new to C# and .NET and any advice would be appreciated - I am sure I am missing something obvious? Thanks

You don´t need to override the method. As you inherit from an interface just add a new method to the interface `Task GetTemplateByIdAsync(string templateId);` — Martin E, Jun 16 '20 at 14:09
What you want is a new overload. [override](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/override) is used "to extend or modify the abstract or virtual implementation of an inherited method, property, indexer, or event" — Broots Waymb, Jun 16 '20 at 14:09

score 3 · Accepted Answer · answered Jun 16 '20 at 14:10

3

The other method you want is not an override, override means you're overriding a virtual method in the base class. And you have no base class.

Remove the override keyword in your function and it will work as you want.

answered Jun 16 '20 at 14:10

Blindy

65,249
10
91
131

But as he is already using an interface he should add the method overload to it. – Martin E Jun 16 '20 at 14:13
4

You generally don't change public interfaces to suit your needs, but you can do whatever you wish. – Blindy Jun 16 '20 at 14:14
you are right. but he could simply change the type parameter to **object** so he wouldn´t need an overload at all :) – Martin E Jun 16 '20 at 14:16
4

@MartinE - I hope you're being sarcastic. That sounds like an awful approach. – Broots Waymb Jun 16 '20 at 14:22

score 0 · Answer 2 · answered Jun 16 '20 at 14:11

The error is correct. In order to override an existing method it has to have the exact same signature as the method it is overriding. Since your method takes in a string it can't override a method that takes in a Guid. Instead I think you want to overload the method (Overloading and overriding.)

No suitable method to override in C#

2 Answers2