I have a datagrid. One column is a checkbox and I would like to handle when the checkbox of a row is modified.

I have seen this code, that at first it looks what I am looking for, but I have some doubts.

public ObservableCollection<YourDataType> Items
{
    get { return items; }
    set { items = value; NotifyPropertyChanged("Items"); }
}

public YourDataType SelectedItem
{
    get { return selectedItem; }
    set { selectedItem = value; NotifyPropertyChanged("SelectedItem"); }
}

In the view model constructor:

SelectedItem.PropertyChanged  = SelectedItem_PropertyChanged;

In the view model:

private void SelectedItem_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    // this will be called when any property value of the SelectedItem object changes
    if (e.PropertyName == "YourPropertyName") DoSomethingHere();
    else if (e.PropertyName == "OtherPropertyName") DoSomethingElse();
}

My doubt is that in the constructor it is subscribe to the event of the selected item, but the selected item is changed when I select another row in the datagrid. So is it subscribe only once? To which item?

Also, the selected item is null at constructor time, so I guess I will get an null error, I guess.

So I really I am not sure if this really a good solution, and if it is, I don't understand why it can work.

There is another solution to can handle when a property of one of the items in the datagrid is changed? But at first, this solution seems clear and simple.

The solution is from here.

Thanks.

CodePudding user response：

You would have to attach and detach the event handler in the SelectedItem property setter:

public YourDataType SelectedItem
{
    get { return selectedItem; }
    set
    { 
        if (selectedItem != null)
        {
            selectedItem.PropertyChanged -= SelectedItem_PropertyChanged;
        }
        selectedItem = value;
        if (selectedItem != null)
        {
            selectedItem.PropertyChanged  = SelectedItem_PropertyChanged;
        }
        NotifyPropertyChanged(nameof(SelectedItem));
    }
}