Question

I’ve been trying to get this to work for a while but can’t (I am fairly new to C# and OOP in general).

Basically, I have this piece of code on a second form:

private void button1_Click(object sender, EventArgs e)
{
    if (charCount > 2 && charCount < 30)
    {
        try
        {
            conn.Open();
        }
        catch (Exception ex)
        {
        //Error handling code here
        }
        finally
        {
            conn.Close();
        }
        //Run the SQL statements
        try
        {

        //SQL insert data is here

        }
        catch (Exception ie)
        {
            MessageBox.Show(ie.Message);
        }
        finally
        {
            //Close the connection
            if (conn.State != ConnectionState.Closed)
            {
                conn.Close();
            }

            mainForm.refreshCall();

            this.Close();
        }

    }
    else
    {
        MessageBox.Show("Part numbers can be between 2 and 30 characters.\n Yours was " + charCount + " characters long.", "Error");
    }

}

It all runs fine and does what it’s supposed to, which is insert some data into a SQL database (I took that code out to make it a little cleaner). So after all that happens, I try to execute mainForm.refreshCall(). This refreshCall method exists on my first form, or mainForm, and looks like this:

public static void refreshCall()
{
    SqlConnection conn = new SqlConnection("Data Source=DSERVER\\NEW_SQL;Initial Catalog=AWSoftware;Integrated Security=True");
    try
    {
        conn.Open();
        DataSet ds = new DataSet();
        SqlDataAdapter adapter = new SqlDataAdapter("SELECT part_num from dbo.CustomParts", conn);
        adapter.Fill(ds);
        this.listParts.DataSource = ds.Tables[0];
        this.listParts.DisplayMember = "part_num";
        conn.Close();
    }

    catch (SqlException odbcEx)
    {
        MessageBox.Show("There was an error connecting to the data source\nError Code: 1001", "Database Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
}

However, this.listParts.DataSource and this.listParts.DisplayMember both tell me that they are not valid static properties Error, static method, or static field initialize. I am absolutely baffled by what that means. If someone would be so kind as to shed some light on this for me, I would greatly appreciate it!

Answer 1

Your refreshCall is marked as static, but you are referencing instantiated variables, in this case, your ListBox, so that won’t work. You either have to pass in the ListBox as a parameter reference, or just remove the static attribute.

Simplest way:

public void refreshCall() {
  // blah-blah
}

then the method call changes to:

this.refreshCall();