WPF Validation: Clearing all validation errors

validationwpf

I have a WPF UserControl with many other controls inside of it.
TextBoxes are among these.
Every TextBox has its own validation:

<TextBox>
    <TextBox.Text>
        <Binding Path="MyPath" StringFormat="{}{0:N}" NotifyOnValidationError="True">
            <Binding.ValidationRules>
                <r:MyValidationRule ValidationType="decimal" />
            </Binding.ValidationRules>
        </Binding>
    <TextBox.Text>
<TextBox>

Now suppose the user types some invalid characters into them. They will all become highlighted red.

Now I want to reset all the validation errors (from the incorrect input) and set the recent correct values coming from DataContext.

I set the DataContext in the constructor and I don't want to change it (DataContext = null won't help me then):

DataContext = _myDataContext = new MyDataContext(..);

What I've already found are these classes:

Validation.ClearInvalid(..)
BindingExpression.UpdateTarget();

I think these classes could help me, but they require the Binding of a concrete FrameworkElement and I want to do it globally for all of them.

Should I anyhow iterate through the Visual Tree (which is really what I don't like) or is there any better solution for this?

Best Answer

This is what a BindingGroup is for... You'd set a BindingGroup on a container of all the controls, e.g. the panel that contains them. This would cause the updates to the DataContext to be held until you call UpdateSources on the BindingGroup. If you want to reset the user's input, you'd call CancelEdit instead, and the BindingGroup would reset all controls inside the container to the (still unchanged) values of the DataContext.

Related Solutions

C# – Binding a WPF ComboBox to a custom list

You set the DisplayMemberPath and the SelectedValuePath to "Name", so I assume that you have a class PhoneBookEntry with a public property Name.

Have you set the DataContext to your ConnectionViewModel object?

I copied you code and made some minor modifications, and it seems to work fine. I can set the viewmodels PhoneBookEnty property and the selected item in the combobox changes, and I can change the selected item in the combobox and the view models PhoneBookEntry property is set correctly.

Here is my XAML content:

<Window x:Class="WpfApplication6.Window1"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="Window1" Height="300" Width="300">
<Grid>
    <StackPanel>
        <Button Click="Button_Click">asdf</Button>
        <ComboBox ItemsSource="{Binding Path=PhonebookEntries}"
                  DisplayMemberPath="Name"
                  SelectedValuePath="Name"
                  SelectedValue="{Binding Path=PhonebookEntry}" />
    </StackPanel>
</Grid>
</Window>

And here is my code-behind:

namespace WpfApplication6
{

    /// <summary>
    /// Interaction logic for Window1.xaml
    /// </summary>
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();
            ConnectionViewModel vm = new ConnectionViewModel();
            DataContext = vm;
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            ((ConnectionViewModel)DataContext).PhonebookEntry = "test";
        }
    }

    public class PhoneBookEntry
    {
        public string Name { get; set; }

        public PhoneBookEntry(string name)
        {
            Name = name;
        }

        public override string ToString()
        {
            return Name;
        }
    }

    public class ConnectionViewModel : INotifyPropertyChanged
    {
        public ConnectionViewModel()
        {
            IList<PhoneBookEntry> list = new List<PhoneBookEntry>();
            list.Add(new PhoneBookEntry("test"));
            list.Add(new PhoneBookEntry("test2"));
            _phonebookEntries = new CollectionView(list);
        }

        private readonly CollectionView _phonebookEntries;
        private string _phonebookEntry;

        public CollectionView PhonebookEntries
        {
            get { return _phonebookEntries; }
        }

        public string PhonebookEntry
        {
            get { return _phonebookEntry; }
            set
            {
                if (_phonebookEntry == value) return;
                _phonebookEntry = value;
                OnPropertyChanged("PhonebookEntry");
            }
        }

        private void OnPropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }
        public event PropertyChangedEventHandler PropertyChanged;
    }
}

Edit: Geoffs second example does not seem to work, which seems a bit odd to me. If I change the PhonebookEntries property on the ConnectionViewModel to be of type ReadOnlyCollection, the TwoWay binding of the SelectedValue property on the combobox works fine.

Maybe there is an issue with the CollectionView? I noticed a warning in the output console:

System.Windows.Data Warning: 50 : Using CollectionView directly is not fully supported. The basic features work, although with some inefficiencies, but advanced features may encounter known bugs. Consider using a derived class to avoid these problems.

Edit2 (.NET 4.5): The content of the DropDownList can be based on ToString() and not of DisplayMemberPath, while DisplayMemberPath specifies the member for the selected and displayed item only.

C# – How to a WPF UserControl inherit a WPF UserControl

Ensure that you have changed the first tag in the xaml to also inherit from your new basetype

<UserControl x:Class="TestDependencyProperty827.DataTypes.DataTypeWholeNumber"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        
    xmlns:s="clr-namespace:System;assembly=mscorlib"
    >

becomes

<myTypes:BaseDataType x:Class="TestDependencyProperty827.DataTypes.DataTypeWholeNumber"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        
    xmlns:s="clr-namespace:System;assembly=mscorlib"
    xmlns:myTypes="clr-namespace:TestDependencyProperty827.DataTypes"
    >

So, to summarise the complete answer including the extra details from the comments below:

The base class should not include a xaml file. Define it in a single (non-partial) cs file and define it to inherit directly from Usercontrol.
Ensure that the subclass inherits from the base class both in the cs code-behind file and in the first tag of the xaml (as shown above).

Best Answer

Related Solutions

C# – Binding a WPF ComboBox to a custom list

C# – How to a WPF UserControl inherit a WPF UserControl

Related Topic