Problem with DataBindings, please explain

Question

public partial class Form1 : Form { MyClass myClass = new MyClass("one", "two"); public Form1() { InitializeComponent(); textBox1.DataBindings.Add("Text", myClass, "Text1", false, DataSourceUpdateMode.Never); textBox2.DataBindings.Add("Text", myClass, "Text2", false, DataSourceUpdateMode.Never); } private void saveButton_Click(object sender, EventArgs e) { myClass.Text1 = textBox1.Text; myClass.Text2 = textBox2.Text; //textBox1.DataBindings["Text"].WriteValue(); //textBox2.DataBindings["Text"].WriteValue(); } } public class MyClass : INotifyPropertyChanged { private string _Text1; private string _Text2; public event PropertyChangedEventHandler PropertyChanged; public string Text1 { get { return _Text1; } set { _Text1 = value; OnPropertyChanged(new PropertyChangedEventArgs("Text1")); } } public string Text2 { get { return _Text2; } set { _Text2 = value; OnPropertyChanged(new PropertyChangedEventArgs("Text2")); } } public MyClass(string text1, string text2) { Text1 = text1; Text2 = text2; } protected void OnPropertyChanged(PropertyChangedEventArgs e) { if (PropertyChanged != null) PropertyChanged(this, e); } } 

I think I understand what I'm trying to achieve. I want my form to save the changes made in my two TextBox es to myClass . But whenever I press the save button after editing both text fields and saveButton_Click is called, the second textBox2 Text returns to the original text (“two”). I tried using the Binding WriteValue function, but the same thing happens. Using .net 4.0.

Edit Thanks for your answers, but I don't need workarounds. I can find them myself. I just need to understand a little better how binding works. I would like to understand why this is happening?

Answer 1

Apparently, updating any value in the data source will update all the bindings. This explains the behavior (setting myClass.Text1 causes myClass.Text1 be updated with the current value myClass.Text2 ). Unfortunately, a few posts I could find simply said, "how does it work."

One way to handle this is to create a BindingSource , set BindingSource.DataSource = myClass , and then bind your text fields to BindingSource .

BindingSource raises ListChanged events if the main data source is a list and items are added, deleted, etc., or if the properties of the DataSource changed. You can suppress these events by setting BindingSource.RaiseListChangedEvents to false , which allows you to set multiple properties on myClass without updating the data binding of the associated controls.

 public partial class Form1 : Form { MyClass myClass = new MyClass("one", "two"); BindingSource bindingSource = new BindingSource(); public Form1() { InitializeComponent(); bindingSource.DataSource = myClass; textBox1.DataBindings.Add("Text", bindingSource, "Text1", true, DataSourceUpdateMode.Never); textBox2.DataBindings.Add("Text", bindingSource, "Text2", true, DataSourceUpdateMode.Never); } private void button1_Click(object sender, EventArgs e) { bindingSource.RaiseListChangedEvents = false; myClass.Text1 = textBox1.Text; myClass.Text2 = textBox2.Text; bindingSource.RaiseListChangedEvents = true; } } 

NTN

Answer 2

You need to change the way data is bound. Try it.

 MyClass myClass = new MyClass("one", "two"); public Form1() { InitializeComponent(); textBox1.DataBindings.Add("Text", myClass, "Text1", false, DataSourceUpdateMode.OnPropertyChanged); textBox2.DataBindings.Add("Text", myClass, "Text2", false, DataSourceUpdateMode.OnPropertyChanged); } private void saveButton_Click(object sender, EventArgs e) { // your object should already have new text values entered. // Save your object! //myClass.Text1 = textBox1.Text; //myClass.Text2 = textBox2.Text; //textBox1.DataBindings["Text"].WriteValue(); //textBox2.DataBindings["Text"].WriteValue(); } 

The key is DataSourceUpdateMode, this will allow the text property of the text field to be cascaded into your custom object whenever the property changes. Hope this helps.

[change]

I believe what you need to do to achieve what you are asking for: TextBox1.DataBindings[0].ControlUpdateMode = ControlUpdateMode.Never This link should contain additional information.