Question

Updated to be more clear….

I have a main form, Form1, and an additional class, AslLib. Form1 contains a method that updates a dataGridView control it contains. A method in AslLib calls this method.

My problem is that the only way I can make AslLib call Form1‘s method is by creating an instance of Form1 in AslLib‘s calling method like so:

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();
    }

    public void updateDataGUI(int row, string url, string status, long time)
    {
        Console.WriteLine(status);
        foreach (DataGridViewRow dgvr in dataGridView1.Rows) dgvr.Cells[0].Value = status;
    }

}



static class AslLib
{
    public static async void makeRequest(string url, int row )
    {
        string result;
        Stopwatch sw = new Stopwatch(); sw.Start();

        try
        {
            using (HttpClient client = new HttpClient())
            {
                HttpResponseMessage response = new HttpResponseMessage();
                response = await client.GetAsync(url);

                if (response.IsSuccessStatusCode)
                {
                    result = ((int)response.StatusCode).ToString();
                }
                else
                {
                    result = ((int)response.StatusCode).ToString();
                }
            }
        }
        catch (HttpRequestException hre)
        {
            result = "Server unreachable";
        }

        sw.Stop();
        long time = sw.ElapsedTicks / (Stopwatch.Frequency / (1000L * 1000L));


        _form.updateDataGUI(row, url, result, time);

    }
}

I have tried passing parameters in both the constructor and the method, but because (i think) the makeRequest method is static, the compiler is giving errors:

AsyncURLChecker.AslLib._form: cannot declare instance members in a static class              AsyncURLChecker
Static classes cannot have instance constructors                AsyncURLChecker

The result of the above is that the Console.WriteLine(status); part of Form1‘s method correctly outputs status, but the dataGridView does not change.

My belief is that because I am creating a new instance of Form1, I am no longer referencing the original Form1 containing my dataGridView, rather an entirely new copy, so it is not changing.

Can anyone tell me how I might manipulate the original Form1’s dataGridView from another class? My preferred method would be to call a Form1 method that updates dataGridView rather than directly accessing dataGridGiew from AslLib if possible.

Answer 1

You should pass reference to existing form instead of creating new one:

// on Form1
Class1 c1 = new Class1();
c1.DoSomething(this);

// Class1
public void DoSomething(Form1 form)
{
    form.updateDataGUI(row, url, result, time);
}