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Dialog Chain In Microsoft Bot Framework

In this article, we will discuss the Dialog chain in the Microsoft Bot Framework.

What Is A Dialog Chain?

In the earlier article, we have created a dialog (inherited from the IDialog interface). We have few constraints with this approach

Strings are hard-coded.
The syntax is cumbersome (so many if and else).

To address the above 2 issues, we can use a dialog chain in the Bot framework. Dialog chain addresses the issue using the following

Dialog chains use regular expressions instead of the hard-coded string.
Uses fluent interface. Fluent interface means writing the code in a more readable form.

Example

In this example, we will follow these steps

Create a new class "MyDialogChain".
Add the following code inside the class.

using Microsoft.Bot.Builder.Dialogs;
using System.Linq;
using System.Text.RegularExpressions;

namespace Bot_Application1.Dialogs {
	public class MyDialogChain {
		public static readonly IDialog < string > dialog = Chain.PostToChain().Select(x = >x.Text).Switch(
		Chain.Case(
		new Regex("^hi", RegexOptions.IgnoreCase), (context, text) = >Chain.Return("Good day!!!").PostToUser()), 
    Chain.Case(
		new Regex("^how are you", RegexOptions.IgnoreCase), (context, text) = >Chain.Return("I am fine, thanks for asking. How may I help you?").PostToUser()), 
    Chain.Default < string, IDialog < string >> ((context, text) = >Chain.Return("I didn't get your question").PostToUser())).Unwrap();
	}
}

Call the class inside the "MessagesController".

Picture showing calling the MyDialogChain class inside the MessageController

Click to Enlarge

Output

Click to Enlarge

Posted By -	Karan Gupta

Posted On -	Monday, October 12, 2020

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