Ask user to save before closing then exit the winform application

Question

My below code should ask the user before closing the form, if no then exit the application itself.

private void DataEntry_FormClosing(object sender, FormClosingEventArgs e)  
    {  
        try  
        {  
            String msg = "Confirm Save?";  
            String caption = "Save Record";  
            MessageBoxButtons buttons = MessageBoxButtons.YesNo;  
            MessageBoxIcon ico = MessageBoxIcon.Question;  
            DialogResult result;  
            result = MessageBox.Show(this, msg, caption, buttons, ico);  
            if (result == DialogResult.Yes)  
            {  
                this.Validate();  
                this.tool_ManagementBindingSource.EndEdit();  
                this.tableAdapterManager.UpdateAll(this.pINQCDataSet);  
                MessageBox.Show("The Record saved Successfully", "Save_Update",  
                    MessageBoxButtons.OK, MessageBoxIcon.Information);  
  
            }  
            else  
            {  
                Application.Exit();   
            }  
        }  
        catch (Exception ex)  
        {  
            MessageBox.Show("Saving Failed:" + ex.Message.ToString(), "Save",  
                MessageBoxButtons.OK, MessageBoxIcon.Error);  
        }  
    }  

But I am getting message box appeared twice even after clicking no , then the below error appears , please guide me how to solve this problem.
@Karen Payne MVP :pls help me.

Answer 1

Use

e.Cancel = true ;

instead of

Application.Exit( )

then in FormClosed try call

  Application.ExitThread();

Answer 2

Greetings, I took an existing code sample, added code to detect changes and then prompt for exit without saving or save and close.

It uses MS-Access but does not matter as all that matters is the DataTable in the DataSet.

Source code

Form code

using System;
using System.ComponentModel;
using System.Windows.Forms;
using Access1.Classes;
using static Access1.Classes.Dialogs;

namespace Access1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            Closing += OnClosing;
        }

        private void OnClosing(object sender, CancelEventArgs e)
        {
            if (dataSet1.Tables[0].HasChanges())
            {
                if (Question("Save before exiting"))
                {
                    SaveChanges();
                }
                else
                {
                    e.Cancel = false;
                }
            }

        }

        private void personBindingNavigatorSaveItem_Click(object sender, EventArgs e)
        {
            SaveChanges();
        }

        private void SaveChanges()
        {
            Validate();
            personBindingSource.EndEdit();
            tableAdapterManager.UpdateAll(dataSet1);
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            personTableAdapter.Fill(dataSet1.Person);
        }
    }
}

MessageBox

public static class Dialogs
{
    public static bool Question(string text)
    {
        return (MessageBox.Show(
            text,
            Application.ProductName,
            MessageBoxButtons.YesNo,
            MessageBoxIcon.Question,
            MessageBoxDefaultButton.Button2) == DialogResult.Yes);
    }
}

Detect changes (can be optimize, wrote it fast)

public static class ExtensionMethods
{
    public static bool HasChanges(this DataTable table)
    {
        var added = table.GetChanges(DataRowState.Added);
        if (added != null)
        {
            return true;
        }

        var deleted = table.GetChanges(DataRowState.Deleted);
        if (deleted != null)
        {
            return true;
        }

        var modified = table.GetChanges(DataRowState.Modified);
        if (modified != null)
        {
            return true;
        }

        return false;
    }

}