C# Winforms - Data Bindings with Same Property Name for Different Controls

Question

I am using data bindings in my Winforms application to connect the UI elements to an underlying object. My UI has several ComboBoxes in it, each pertaining to a different property of the class. Take the following simplified code, for example:

Object which implements INotifyPropertyChange

class MyObject : INotifyPropertyChange
{
    // Custom logic in setters calls OnPropertyChanged
    public int Property1 { get; set; }
    public string Property2 { get; set; }
}

Assigning the data source

BindingSource MyDataSource = new BindingSource(this.components);
MyDataSource.Add(instanceOfMyObject);

Creating bindings

Binding binding1 = new Binding("SelectedIndex", MyDataSource, "Property1",
                                false, DataSourceUpdateMode.OnPropertyChanged);
binding1.Format += FormatForBinding1();
comboBox1.DataBindings.Add(binding1);

Binding binding2 = new Binding("SelectedIndex", MyDataSource, "Property2"
                                false, DataSourceUpdateMode.OnPropertyChanged);
binding2.Format += FormatForBinding2();
comboBox2.DataBindings.Add(binding2);

My issue is that when comboBox2.SelectedIndex changes, both Format handlers are called, which is not desired, when I only want FormatForBinding2() to be invoked. Is there a way to solve this? Am I misunderstanding something about bindings in that I cannot have multiple bindings with the same property name and the same data source, although the controls are different?

Answer 1

I think the issue was with the code being executed in the Format handlers. The Format handler should only be used to do what it's name implies -- format the value. Adding extra logic can lead to undesirable behavior, as I found out. One thing to consider is, along with the Format handler, also including a SelectedIndexChanged or SelectedValueChanged handler for the desired ComboBox and doing the other logic in there.