C# and Generics: how can I handle processing based on type?

Question

I'm new to generics and I'm trying to make a generic HTTP GET method for my project (and possibly expand it to handle POST/PUT also). The following seems to work OK when the response is string based:

private async Task<T> HttpGetAsync<T>(Uri uri)
{
    var httpRequestMessage = new HttpRequestMessage()
    {
        Method = HttpMethod.Get,
        RequestUri = uri,
        Headers =
        {
            { "Authorization", $"Basic {encodedCredentials}"},
            { "Cache-Control", "no-cache" }
        }
    };

    var response = await _httpClient.SendAsync(httpRequestMessage);
    var content = await response.Content.ReadAsStringAsync();
    return JsonConvert.DeserializeObject<T>(content);
}

But in some cases, based on the type, I would like the response to be read using ReadAsByteArrayAsync() or ReadAsStreamAsync() instead of ReadAsStringAsync().

I think that I could probably do a getType() within the method, and read the response using the appropriate method, but I'm wondering if maybe there is a better way to do this?

Is this a bad idea/a bad usage of generics in general? Thanks for any information!

Answer 1

Use an interface:

interface IContentReader<T>
{
    T ReadAsync(HttpResponseMessage response);
}

private async Task<T> HttpGetAsync<T>(Uri uri, IContentReader<T> reader)
{
    var httpRequestMessage = new HttpRequestMessage()
    {
        Method = HttpMethod.Get,
        RequestUri = uri,
        Headers =
        {
            { "Authorization", $"Basic {encodedCredentials}"},
            { "Cache-Control", "no-cache" }
        }
    };

    var response = await _httpClient.SendAsync(httpRequestMessage);
    return await reader.ReadAsync(response);
}

And you can have different implementations of IContentReader<T>. You can determine which implementation to use based on T.