Clear code: SRP and Open / Closed when retrieving data from web services

Question

When I develop, I usually try to follow the principles of SOLID . Usually you have an interface that is implemented by all affected classes, and then use the interface as a parameter in further calculations.

My question is: how can this be achieved when calling, for example, a web service? The code below is not very skinny and really does NOT correspond to a single template of responsibility and the principle of open / closed.

How would you reverse engineer the following code to follow SRP and O / C:

    public class Fetch
    {
        public void Run()
        {
            var url = "https://api.nasa.gov/planetary/apod?api_key=NNKOjkoul8n1CH18TWA9gwngW1s1SmjESPjNoUFo";
            var client = new HttpClient();
            var response = client.GetAsync(url).Result;
            var data = response.Content.ReadAsStringAsync().Result;
            var parsedData = JsonConvert.DeserializeObject<Nasa>(data);

            if(parsedData.media_type.Equals("image"))
            {
                CreateImage(parsedData);
            }

            if (parsedData.media_type.Equals("video"))
            {
                CreateVideo(parsedData);
            }

            if (parsedData.media_type.Equals("text"))
            {
                CreateText(parsedData);
            }
        }
    }

    public class Nasa
    {
        public string copyright { get; set; }
        public string date { get; set; }
        public string explanation { get; set; }
        public string hdurl { get; set; }
        public string media_type { get; set; }
        public string service_version { get; set; }
        public string title { get; set; }
        public string url { get; set; }
    }

(The Api key is taken from the Nasa example site, so don’t worry about exposure. The asynchronous part using .Resultis for this example only)

Answer 1

, CreateVideo(item) CreateImage(item), .

, (, Simple Injector, !), ​​.

public class Nasa
{
    public string copyright { get; set; }
    public string date { get; set; }
    public string explanation { get; set; }
    public string hdurl { get; set; }
    public string media_type { get; set; }
    public string service_version { get; set; }
    public string title { get; set; }
    public string url { get; set; }
}

public interface ITransformFetch<in T>
{
    void Transform(T data);
}

public interface IFetch<T> 
{
    T Fetch();
}

public class NasaFetcher : IFetch<Nasa>
{
    private const string NasaUrl = "https://api.nasa.gov/planetary/apod?api_key=NNKOjkoul8n1CH18TWA9gwngW1s1SmjESPjNoUFo";

    private readonly IHttpClientWrapper _client;

    public NasaFetcher(IHttpClientWrapper client)
    {
        _clientFactory = client;
    }

    public Nasa Fetch()
    {
        var response = _client.GetAsync(NasaUrl).Result;
        var data = response.Content.ReadAsStringAsync().Result;
        return JsonConvert.DeserializeObject<Nasa>(data);
    }
}

public class NasaFetchImageTransformer : ITransformFetch<Nasa>
{
    public void Transform(Nasa data)
    {
        // transform data
    }
}

public class NasaFetchVideoTransformer : ITransformFetch<Nasa>
{
    public void Transform(Nasa data)
    {
        // transform data
    }
}

public class NasaFetcherTransformerDecorator : IFetch<Nasa>
{
    private readonly IFetch<Nasa> _fetcher;

    public NasaFetcherTransformerDecorator(IFetch<Nasa> fetcher)
    {
        _fetcher = fetcher;
    }

    public Nasa Fetch()
    {
        var result = _fetcher.Fetch();
        if (result != null)
        {
            switch (result.media_type)
            {
                case "image":
                    var nasaFetchImageTransformer = new NasaFetchImageTransformer();
                    nasaFetchImageTransformer.Transform(result);
                    break;

                case "video":
                    var nasaFetchVideoTransformer = new NasaFetchVideoTransformer();
                    nasaFetchVideoTransformer.Transform(result);
                    break;
            }
        }

        return result;
    }
}

public class Test
{
    public void TestNasaFetcher()
    {
        var data = new NasaFetcherTransformerDecorator(new NasaFetcher(new HttpClientWrapper()));
        var nasa = data.Fetch();
    }
}