Startup.cs

public class Startup
{
    private readonly IHostingEnvironment _hostingEnvironment;

    public Startup(IHostingEnvironment hostingEnvironment)
    {
        _hostingEnvironment = hostingEnvironment;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc()
            .SetCompatibilityVersion(CompatibilityVersion.Version_2_2)
            .AddJsonOptions(options =>
            {
                options.SerializerSettings.Formatting = _hostingEnvironment.IsDevelopment() 
                    ? Formatting.Indented 
                    : Formatting.None;
            });
    }
    // Other code ommitted for brevity
}