Question

I have the following Controllers (in diagram) which Call the Static method to get the data. As I am going to use the data at many other pages , I dont want to requets for the data again and again. That’s why I am checking whether data is null and then returning the value appropriately.

private static IEnumerable<MovieDetails> GetJsonData(string jsonRequestURL)
{
    try
    {
        using (var wc = new WebClient())
        {
            var json = wc.DownloadString(jsonRequestURL);
            var rootObj = JsonConvert.DeserializeObject<MoviesListRootObject>(json);

            var responseObject = rootObj.movieResponse;

            var movieDetails = responseObject.Select(movieDetail =>
                                                        new MovieDetails
                                                        {
                                                            Description = movieDetail.description,
                                                            MovieURI = movieDetail.formats.res150p,
                                                            Thumbnail = movieDetail.image,
                                                            Title = movieDetail.title,
                                                            ID = movieDetail.id
                                                        });
            return movieDetails;
        }
    }

    catch (Exception exception)
    {
        //Error Handling
    }
}

This is perfect till the time, GetJsonData is Desrializng to only One type(Currently MoviesListRootObject what If I want to ConvertTo AnotherType of Root object ex: FeaturedlistRootObject).

But how in the same method I can Desirialing to other types?

Are generics the only option or there exist some better design/feature I can use (not sure how helpful dynamic will be)?

Again, if I am only left with generics, can I avoid writing code based on different types?

Answer 1

There seem to be two parts of your code that can change:

1. the type of the root object (e.g. MoviesListRootObject) and the type of the result (e.g. IEnumerable<MovieDetails>)
2. how is the result created from the root object

Generics are the perfect solution for #1, but they won’t help you much with #2, you need some other mechanism for that. Depending on the structure of your code, the best solution for #2 may differ. I think you pretty much have two choices here:

1. make the method generic and use a delegate to create the result
2. make the whole type generic and create the result by calling an abstract method

Choice 1 could look something like this:

private static TResult GetJsonData<TRoot, TResult>(
    string jsonRequestURL, Func<TRoot, TResult> resultSelector)
{
    using (var wc = new WebClient())
    {
        var json = wc.DownloadString(jsonRequestURL);
        var rootObj = JsonConvert.DeserializeObject<TRoot>(json);
        return resultSelector(rootObj);
    }
}

private static IEnumerable<MovieDetails> GetMovieDetails(string jsonRequestURL)
{
    return GetJsonData<MoviesListRootObject, IEnumerable<MovieDetails>>(
        jsonRequestURL,
        rootObj =>
        {
            var responseObject = rootObj.movieResponse;

            var movieDetails = responseObject.Select(
                movieDetail =>
                    new MovieDetails
                    {
                        Description = movieDetail.description,
                        MovieURI = movieDetail.formats.res150p,
                        Thumbnail = movieDetail.image,
                        Title = movieDetail.title,
                        ID = movieDetail.id
                    });
            return movieDetails;
        });
}

This way, the general code for downloading JSON data is separated from the specific code for downloading movie details.