How to Update a WinForm GUI From a Route?

[Milkate]

Hello, I know this is not a Grapevine problem, but how can I update a Winform GUI?

[RestResource]
public class MyResource
{
    [RestRoute("Get", "/api/test")]
    public async Task Test(IHttpContext context)
    {
        await context.Response.SendResponseAsync("Successfully hit the test route!");
        //UpdateGUI
    }

    private void UpdateGui(string text)
    {
        labelx.Text = text;
    }
}

[scottoffen]

You are correct, this is absolutely outside the scope of Grapevine. That being said, I'm sure many people will have this same question, so it's a good idea to address this here. Keep in mind that this is not necessarily the most optimal way to approach doing this, but rather a concise, working example to get you up and running on the right path.

In order to update your WinForms GUI, you have to get a handle to the open form and the specific control you want to update on it. If, for example, you have a form named Form1 that contains a text box named textBox1, and you want to update the textbox, you would import System.Windows.Forms into your route class, and use something like this:

var form = Application.OpenForms["Form1"] as Form1;
var tb = form?.Controls["textBox1"] ?? null;

If you try to interact with that control directly, you will get an System.InvalidOperationException with the message Cross-thread operation not valid: Control 'textBox1' accessed from a thread other than the thread it was created on.

Instead, you want to invoke a delegate:

tb?.Invoke(new MethodInvoker(delegate { tb.Text = "I have updated the value in this text box"; }));

That should get you headed in the right direction!

[scottoffen]

Furthermore, here is the recommended way to add a rest server to your WinForms application, assuming you want the server running throughout your entire application lifecycle.

using System;
using System.Windows.Forms;
using Grapevine;

namespace YourApplication
{
    static class Program
    {
        /// <summary>
        ///  The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            // Configure your server in the Startup class
            var server = RestServerBuilder.From<Startup>().Build();
            server.Start();

            Application.SetHighDpiMode(HighDpiMode.SystemAware);
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());

            server.Stop();
        }
    }
}

Most of that is boilerplate when you create a new WinForm application. The idea is that you create and start your server before the application starts. The line Application.Run(...) will block the thread until the form is exited, at which point you can stop your server.

DO NOT USE server.Run() with a WinForms application, as this blocks the thread until the server is stopped.

[Milkate]

Thanks for tips. I have trying another method you give who work good (with v4):

private void Form1_Load(object sender, EventArgs e)
{
    mServer = new RestServer();
    mServer.Properties.Add("CurrentForm", this);
}

private void UpdateGuil(string newText)
{
    this.Invoke(new MethodInvoker(() => textBox1.Text = newText));
}

and

var form = context.Server.GetPropertyValueAs<Form1>("CurrentForm");
form.UpdateGui("message");

[Milkate]

Now i need to find how to invoke UpdateGui with Grapevine 5 :)

[scottoffen]

I do not understand your response.