AIChatControl.MessageSending Event

Fires when a user submits a message to the chat.

Namespace: DevExpress.AIIntegration.WinForms.Chat

Assembly: DevExpress.AIIntegration.WinForms.Chat.v26.1.dll

NuGet Package: DevExpress.AIIntegration.WinForms.Chat

Declaration

C#

[DXCategory("Events")]
public event EventHandler<AIChatControlMessageSendingEventArgs> MessageSending

VB.NET

<DXCategory("Events")>
Public Event MessageSending As EventHandler(Of AIChatControlMessageSendingEventArgs)

Event Data

The MessageSending event's data class is DevExpress.AIIntegration.Blazor.Chat.WebView.AIChatControlMessageSendingEventArgs.

Remarks

Handle the MessageSending event to process a user message before the control adds it to chat history and sends it to the AI service. For example, you can log a message to a database, remove personally identifiable information (PII) from the message text, add system instructions, or apply custom logic.

Set the e.Cancel event parameter to true to block automatic message delivery. After cancellation, call the SendMessageAsync method to submit a message manually.

Example

The following example blocks the default delivery flow and sends a modified message to the AI service:

C#

using DevExpress.AIIntegration.Blazor.Chat.WebView;
using Microsoft.Extensions.AI;

public Chat() {
    InitializeComponent();
    aiChatControl1.MessageSending += AiChatControl1_MessageSending;
}

async void AiChatControl1_MessageSending(object sender, AIChatControlMessageSendingEventArgs e) {
    e.Cancel = true;

    StringBuilder sb = new StringBuilder();
    sb.AppendLine("Your message:");
    sb.AppendLine(e.Text);
    e.Text = sb.ToString();
    await e.Chat.SendMessageAsync(sb.ToString());
}

VB.NET

Imports DevExpress.AIIntegration.Blazor.Chat.WebView
Imports Microsoft.Extensions.AI

Public Sub New()
    InitializeComponent()
    AddHandler aiChatControl1.MessageSending, AddressOf AiChatControl1_MessageSending
End Sub

Private Async Sub AiChatControl1_MessageSending(sender As Object, e As AIChatControlMessageSendingEventArgs)
    e.Cancel = True

    Dim sb As New StringBuilder()
    sb.AppendLine("Your message:")
    sb.AppendLine(e.Text)
    e.Text = sb.ToString()
    Await e.Chat.SendMessageAsync(sb.ToString())
End Sub

Use the e.Files and e.Contexts event parameters to access files and AI resources attached to the message.

Refer to the following help topic for additional information: AI Chat Control