BotBuilder -Custom Dialog

MessagesController.cs

internal static IDialog MakeRootDialog()
{
     return new SandwichDialog(SandwichOrder.BuildForm);
}

public async Task<Message> Post([FromBody]Message message)
{
    if (message.Type == "Message")
    {
        return await Conversation.SendAsync(message, MakeRootDialog);
    }
    else
    {
        return HandleSystemMessage(message);
    }
}

SandwichDialog.cs

[Serializable]
public class SandwichDialog : IDialog
{
    private readonly BuildForm<SandwichOrder> SandwichOrderForm;

    internal SandwichDialog(BuildForm<SandwichOrder> SandwichOrderForm)
    {
        this.SandwichOrderForm = SandwichOrderForm;
    }

    public async Task StartAsync(IDialogContext context)
    {
        context.Wait(MessageReceivedAsync);
    }

    public async Task MessageReceivedAsync(IDialogContext context, IAwaitable<Message> argument)
    {
        var message = await argument;
        var sandwichForm = new FormDialog<SandwichOrder>(new SandwichOrder(), this.SandwichOrderForm, FormOptions.PromptInStart);
        context.Call<SandwichOrder>(sandwichForm, FormComplete);
    }

    private async Task FormComplete(IDialogContext context, IAwaitable<SandwichOrder> result)
    {
        SandwichOrder order = null;
        try
        {
            order = await result;
        }          
        catch (OperationCanceledException)
        {
            await context.PostAsync("You canceled the form!");
            return;
        }
        catch (Exception ex)
        {
            await context.PostAsync(ex.Message);
            return;
        }

        if (order != null)
        {
            await context.PostAsync(order.ToString());
        }
        else
        {
            await context.PostAsync("Form returned empty response!");
        }

        context.Wait(MessageReceivedAsync);
    }
}

SandwichOrder.cs

using Microsoft.Bot.Builder.FormFlow;
using System;
using System.Collections.Generic;
using System.Text;
#pragma warning disable 649

// The SandwichOrder is the simple form you want to fill out.  It must be serializable so the bot can be stateless.
// The order of fields defines the default order in which questions will be asked.
// Enumerations shows the legal options for each field in the SandwichOrder and the order is the order values will be presented 
// in a conversation.
namespace Bot_Application1
{
    public enum SandwichOptions
    {
        BLT, BlackForestHam, BuffaloChicken, ChickenAndBaconRanchMelt, ColdCutCombo, MeatballMarinara,
        OverRoastedChicken, RoastBeef, RotisserieStyleChicken, SpicyItalian, SteakAndCheese, SweetOnionTeriyaki, Tuna,
        TurkeyBreast, Veggie
    };
    public enum LengthOptions { SixInch, FootLong };
    public enum BreadOptions { NineGrainWheat, NineGrainHoneyOat, Italian, ItalianHerbsAndCheese, Flatbread };
    public enum CheeseOptions { American, MontereyCheddar, Pepperjack };
    public enum ToppingOptions
    {
        Avocado, BananaPeppers, Cucumbers, GreenBellPeppers, Jalapenos,
        Lettuce, Olives, Pickles, RedOnion, Spinach, Tomatoes
    };
    public enum SauceOptions
    {
        ChipotleSouthwest, HoneyMustard, LightMayonnaise, RegularMayonnaise,
        Mustard, Oil, Pepper, Ranch, SweetOnion, Vinegar
    };

    [Serializable]
    class SandwichOrder
    {
        public SandwichOptions? Sandwich;
        public LengthOptions? Length;
        public BreadOptions? Bread;
        public CheeseOptions? Cheese;
        public List<ToppingOptions> Toppings;
        public List<SauceOptions> Sauce;

        public static IForm<SandwichOrder> BuildForm()
        {
            return new FormBuilder<SandwichOrder>()
                    .Message("Welcome to the simple sandwich order bot!")                    
                    .Build();
        }

        public override string ToString()
        {
            var builder = new StringBuilder();
            builder.Append("You have place an order!!");
            return builder.ToString();
        }

    };
}