services.AddMvc()
        // ------
        .ConfigureForms(typeof(Startup).Assembly) // specify each assembly that contains form models
        .EnableFormsController(typeof(Startup).Assembly) // optionally generates a Controller for each form under /forms/<form-slug>
        // ------
        .SetCompatibilityVersion(CompatibilityVersion.Version_2_2);

    [Info("Kitchen sink")]
    public class KitchenSink
    {
        // Simple, single line text box
        [Text]
        public string StringField { get; set; }

        // Multi-line text box
        [MultilineText]
        [HintLabel("Optional")] // "hint text" can be rendered via a TagHelper within a component view
        public string MultilineStringField { get; set; }

        // Renders as a HTML5 number field
        [Numeric]
        public int NumericField { get; set; }

        // A boolean (Yes/No) checkbox
        [Boolean]
        public bool BooleanField { get; set; }

        [Date]
        [HintLabel("Must be a valid date")]
        public DateTime DateField { get; set; }

        [Date]
        [HintLabel("Optional date that can be empty")]
        public DateTime? DateField { get; set; }

        // Presents a basic file upload input
        [Upload]
        [HintLabel("Maximum file size of 5MB")]
        public IFormFile UploadField { get; set; }

        // A "Choice" presents a list of possible values and text labels, the presentation depends on the type definition

        // A nullable type will present all available options along with a default "empty" option
        [Choice]
        public DayOfWeek? OptionalSingleSelect { get; set; }

        // Using an Enum type like `DayOfWeek` will render each item from the Enum
        [Choice]
        public DayOfWeek RequiredSingleSelect { get; set; }

        // Using an Enumerable type will present a multi-select box where more than 1 item can be selected
        [Choice]
        public IEnumerable<DayOfWeek> MultiSelect { get; set; }

        [Choice]
        [HintLabel("Be colourful!")]
        public ConsoleColor ColourSelect { get; set; }

        // The `ChoiceDataSource` allows dynamic values to be presented for a given choice field, see examples below

        [Choice]
        [ChoiceDataSource(typeof(ListOfPostcodesDataSource))]
        public string Postcode { get; set; }

        [Choice]
        [ChoiceDataSource(typeof(ListOfOptionsDataSource))]
        public int? FromListOfOptions { get; set; }
    }

    ///
    /// <summary>Creates a simple list of choices</summary>
    ///
    public class ListOfOptionsDataSource : IChoiceDataSource
    {
        public async Task<IEnumerable<ChoiceItem>> GetAsync()
        {
            return await Task.FromResult(new List<ChoiceItem> { 
                new ChoiceItem("1", "Option 1"), 
                new ChoiceItem("2", "Option 2"), 
                new ChoiceItem("3", "Option 3"), 
            });
        }
    }

    ///
    /// <summary>Dynamically retrieves a list of postcodes to present as choices</summary>
    ///
    public class ListOfPostcodesDataSource : IChoiceDataSource
    {
        private readonly string postcode;
        private readonly HttpClient client;

        public ListOfPostcodesDataSource(IHttpClientFactory httpClientFactory)
        {
            postcode = "eh6";
            client = httpClientFactory.CreateClient();
        }

        public async Task<IEnumerable<ChoiceItem>> GetAsync()
        {
            try
            {
                var data = await client.GetStringAsync($"https://api.postcodes.io/postcodes?q={postcode}&limit=100");
                var result = JsonConvert.DeserializeObject<Root>(data);
                if (result.status == 200)
                {
                    return result.result.Select(c => new ChoiceItem(c.postcode, c.postcode));
                }
            }
            catch
            {
                // argh, testing!
            }

            return Enumerable.Empty<ChoiceItem>();
        }

        public class Root
        {
            public int status { get; set; }
            public Result[] result { get; set; }
        }

        public class Result
        {
            public string postcode { get; set; }
            public string nhs_ha { get; set; }
            public string primary_care_trust { get; set; }

        }
    }