getter setter 无法在 Winform 中更改 textBox.Text 控件值 c#

Question

Why textBox3.text do not shows value _TextBoxRequestMsg. MessageBox opens and shows _TextBoxRequestMsg value OK, console prints too.

public partial class F_Main : Form
{
    private string _TextBoxRequestMsg;

    public string TextBoxRequestMsg
    {
        get { return textBox3.Text; }
        set
        {
            _TextBoxRequestMsg = value;
            MessageBox.Show(_TextBoxRequestMsg);       
            Console.WriteLine(_TextBoxRequestMsg);    
            textBox3.Text = _TextBoxRequestMsg;         
        }
    }

    public F_Main()
    {
        InitializeComponent();
    }
}

public class CdataController : ApiController
{
    F_Main mainForm = new F_Main();

    public async Task<HttpResponseMessage> PostPayloadEventsOp(string SN, string table, string OpStamp)
    {
        using (var contentStream = await this.Request.Content.ReadAsStreamAsync())
        {
            contentStream.Seek(0, SeekOrigin.Begin);
            using (var sr = new StreamReader(contentStream))
            {
                string results = sr.ReadToEnd();
                mainForm.TextBoxRequestMsg = results;                    
            }
        }
        HttpResponseMessage response = Request.CreateResponse(HttpStatusCode.OK);
        response.Content = new StringContent("OK", System.Text.Encoding.UTF8);
        response.Headers.CacheControl = new CacheControlHeaderValue()
        {
            MaxAge = TimeSpan.FromMinutes(2)
        };
        return response;
    }
}

Answer 1

Your question states that your goal is to change textBox.Text control value in Winform and your code indicates that you want to do this by processing an HttpResponseMessage . Consider that the Form that owns the textBox3 control could await the response so that it can meaningfully process its content and assign the value to the text box.

---

For a minimal example, mock the API request:

public class MockCdataController : ApiController
{
    public async Task<HttpResponseMessage> MockPostPayloadEventsOp(string SN, string table, string OpStamp)
    {
        using (HttpClient client = new HttpClient())
        {
            HttpResponseMessage response = await client.GetAsync("https://stackoverflow.com/q/75310027/5438626"); 
            response.Content = new StringContent("OK", System.Text.Encoding.UTF8);
            response.Headers.CacheControl = new CacheControlHeaderValue()
            {
                MaxAge = TimeSpan.FromMinutes(2)
            };
            return response;
        }
    }
}

---

The Form that is in possession of textBox3 could invoke something like this:

public partial class MainForm : Form
{
    public MainForm()
    {
        InitializeComponent();
        buttonPost.Click += onPost;
    }
    private async void onPost(object? sender, EventArgs e)
    {
        try
        {
            UseWaitCursor = true;
            buttonPost.BackColor = Color.LightGreen;
            var response = await _controller.MockPostPayloadEventsOp("38D6FF5-F89C", "records", "Asgard");
            if((response.Headers != null) && (response.Headers.CacheControl != null))
            {
                textBox3.Text = $"{response.Headers.CacheControl.MaxAge}";
            }  
        }
        finally
        {
            UseWaitCursor = false;
            Cursor.Position = new Point(Cursor.Position.X + 1, Cursor.Position.Y);
        }
    }
    MockCdataController _controller = new MockCdataController();
}