Check if data has changed after setting binding source

Question

I use a binding source so that all my controls are bound to datasource. Like this:

var category = categoryRequest.Get(id);
bindingSource.DataSource = category;

This works fine.

I've also implemented INotifyPropertyChanged on the DTO classes (even though this should not be done), so that a change in the object's properties is reflected immediately in the corresponding controls. This also works.

However, if the user loads an object, changes some text in some controls and decides to close the form, I would like to determine if data has been changed and prompt a "Are you sure?" message.

Currently, the way I'm doing it is like this:

    public static bool DataChanged(this Form form)
    {
        bool changed = false;

        if (form == null)
            return changed;

        foreach (Control c in form.Controls)
        {
            switch (c.GetType().ToString())
            {
                case "TextBox":
                    changed = ((TextBox)c).Modified;
                    break;

                //Other control types here...
            }

            if (changed)
                break;
        }

        return changed;
    }

But I don't think this is the best way to do it because:

1. Each control type needs to the added manually
2. Checking if lists have changed won't work

Is there a better way to achieve what I need?

Answer 1

Do you want to check it only once? Like before closing the window.. If you do you can

declare public static bool changed=false; in the form class and change its value to true from where you have implimented the INotifyPropertychanged.

you can display a messagebox anywhere in the form as follows.

     if(changed)
     {
        if (MessageBox.Show("Are you sure?","some caption",MessageBoxButtons.YesNo)==DialogResult.Yes)
        {
                //Do this if user presses YES
        }
      }

Answer 2

Just subscribe to the BindingSource's ListChanged event and set an IsDirty flag based on the event.

categoryBindingSource.ListChanged += new System.ComponentModel.ListChangedEventHandler(categoryBindingSource_ListChanged);

and set IsDirty = true in the event method...

void customerAccountBindingSource_ListChanged(object sender, system.ComponentModel.ListChangedEventArgs e) { if (e.ListChangedType == System.ComponentModel.ListChangedType.ItemChanged) _isDirty = true;

    }

Answer 3

I realize this is an older thread, but I would suggest a simple solution:

if (YourTextBox.Modified)
{
    // Your code goes here.
}

I think it has been around since version 1.0. You will find further information here.