Calling a T Method and converting results to string C#

Question

I have the following generic method:

        public T GetUserPreference<T>(string keyName, string programName)
        {
            string json = preferencesRepository.GetUserPreference(keyName, programName);
            if (json != null)
            {
                try
                {
                    return JsonSerializer.Deserialize<T>(json);
                }
                catch (Exception ex)
                {
                    Logger.LogError(ex, nameof(GetUserPreference));
                }
            }
            return default(T);
        }

Here is the code for my GetUserPreference method:

        public string GetUserPreference(string key, string programName)
        {
            string query = { Retrieving data from a varbinary field in SQL }
            List<SqlParameter> sqlParams = new List<SqlParameter>
            {
                new SqlParameter("@Username", SqlDbType.VarChar) { Value = GlobalUserName },
                new SqlParameter("@ProgramName", SqlDbType.VarChar) { Value = programName },
                new SqlParameter("@KeyName", SqlDbType.VarChar) { Value = key }
            };
            try
            {
                object preferenceResult = Data.ExecuteScalar(query, SqlServerConnectionString, sqlParams.ToArray());
                return preferenceResult == null ? null : Encoding.UTF8.GetString((byte[])preferenceResult);
            }
            catch (Exception ex)
            {
                logger.LogError(ex, "");
            }
            return null;
        }

I tried calling it like this: string preference = preferencesService.GetUserPreference(key, programName);

But I get the following error:

The type arguments for method 'PreferencesService.GetUserPreference(string, string)' cannot be inferred from the usage. Try specifying the type arguments explicitly.

The Method it is being called from is as follows:

        [ApiVersion("1.0")]
        [HttpGet("v{version:apiVersion}/Preferences", Name = "Get User Preference")]
        public IActionResult Get(string key, string programName)
        {
            string preference = preferencesService.GetUserPreference<T>(key, programName);
            if (preference == null)
            {
                return new NoContentResult();
            }
            return Content(preference);
        }

How do I call this generic method ?

Answer 1

You can explicitly specify the type argument of a generic method by adding it like in the definition:

string preference = preferencesService.GetUserPreference<TheActualTypeYouKnowItIs>(key, programName);

C# compiler can't guess it in this context, basically since it would return string for any type argument.