如何在构建Microsoft Bot Framework Form Builder表单前及流程中获取用户输入？

Great question! Catching user inputs like "exit" at any point in a FormFlow process and acting on them is a common requirement, and it's straightforward to implement with FormBuilder's extensibility features. Here's how to do it step by step:

1. Capture User Input & Store in State #

First, you'll need to intercept every user message sent to the form, save it to a state variable, and check if it matches your exit command. Use the MessageReceived method on FormBuilder to inject this custom logic.

Example Form Class #

Let's start with a simple sample form to work with:

public class UserProfileForm
{
    [Prompt("Please enter your full name: {||}")]
    public string FullName { get; set; }

    [Prompt("What's your email address? {||}")]
    public string Email { get; set; }

    [Prompt("How many years of experience do you have? {||}")]
    public int ExperienceYears { get; set; }
}

Add Custom Message Handling #

When building your form, add the MessageReceived handler to capture input, save it to state, and handle the exit command:

public static IForm<UserProfileForm> BuildUserProfileForm()
{
    return new FormBuilder<UserProfileForm>()
        .MessageReceived(async (dialogContext, formState) =>
        {
            // Get and normalize the user's input
            string userInput = dialogContext.Activity.Text?.Trim().ToLower();
            
            // Save input to user-specific state (persists across conversations for this user)
            dialogContext.UserData.SetValue("LastUserInput", userInput);

            // Check if the input is the exit command
            if (userInput == "exit")
            {
                // Send a confirmation message to the user
                await dialogContext.PostAsync("You've exited the form process successfully.");
                
                // Return null to terminate the FormFlow immediately
                return null;
            }

            // If not an exit command, let FormFlow continue processing normally
            return formState;
        })
        .Build();
}

2. Handle Form Termination in Your Dialog #

When the user exits the form, the FormDialog will either return null or throw an OperationCanceledException—you can handle both cases in the resume method:

public async Task StartAsync(IDialogContext context)
{
    // Launch the form dialog
    var formDialog = FormDialog.FromForm(BuildUserProfileForm(), FormOptions.PromptInStart);
    context.Call(formDialog, AfterFormCompletion);
}

private async Task AfterFormCompletion(IDialogContext context, IAwaitable<UserProfileForm> result)
{
    try
    {
        var completedForm = await result;
        // Logic for when the form is filled out successfully
        await context.PostAsync($"Thanks {completedForm.FullName}! We've saved your details.");
    }
    catch (OperationCanceledException)
    {
        // This catches cases where the form was canceled (including our exit command)
        await context.PostAsync("Form process was canceled. Feel free to start again anytime!");
    }
    // End the dialog
    context.Done<object>(null);
}

Key Notes #

• Normalize Input: Using Trim().ToLower() ensures commands like "Exit", "EXIT", or " exit " are all recognized.
• State Storage: Use dialogContext.UserData for user-specific state, or dialogContext.ConversationData if you need the input stored per conversation.
• Flexible Logic: You can extend this handler to support other custom commands (like "help" or "restart") by adding more condition checks.

内容的提问来源于stack exchange，提问作者Loai Tayem