How to reload (reset) the whole page in WPF?

Question

I have Request.xaml with button and with many comboxes, so I want reload it and put combox values to put it to default after button click. Of course I do some more staff.

My Request.xaml code has such parts of the code:

<TextBox x:Name="TxtBlock_numRequest" TextWrapping="Wrap" Height="23"/>

                <ComboBox  x:Name="CmbBox_lvlPriority" Width="160"> 
                   <ComboBoxItem Content="1" Name="High" />
                   <ComboBoxItem Content="2" Name="Medium" />
                   <ComboBoxItem Content="3"  Name="Low" />
                   </ComboBox>    

In addition, xaml code such event <Button Content="Next request" Width="160" VerticalAlignment="Bottom" Background="#FF339933" Click="Button_Click" />

And Request.xaml.cs file have just private void Button_Click(object sender, RoutedEventArgs e) function.

I display Request.xaml this way: first of all, MainWindow.xaml displays MainPage.xaml, <mui:Link DisplayName="Generation" Source="/Pages/MainPage.xaml" />, and finally MainPage.xaml dispays Request.xaml`

Is it possible to reset the whole page, because I need to give user opportunity to add new request's parameters to existing parameters, which eventually will be located in a .xml file?

May be it is possible to realize via OnNavigatedTo Method or by UIElement.InvalidateVisual Method (http://msdn.microsoft.com/en-us/library/system.windows.uielement.invalidatevisual.aspx)

Answer 1

Off course it's possible! But...do you databind the comboboxes to some underlying object instance?

Then you can easily do it the "hard" way and set

page.DataContext = null;
page.DataContext = new Foo();

Then all databinding will be re-initialized with the "default" values.

Answer 2

As far I don`t use MVVM/DataContext, so in that particulal case there is only one way out to set values to default, it is to do it by hand.

TxtBlock_numRequest.Text = "Default";

But this solution looks really bad, but at least it works.

Another way to solve this problem is to use MVVM and DataBinding. This solution was given by @ZeroART:

//XAML
<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        Title="MainWindow" Height="350" Width="525">
    <StackPanel>
        <TextBox x:Name="TextBox1" Width="200" HorizontalAlignment="Left" Text="{Binding TextValue, UpdateSourceTrigger=PropertyChanged}"></TextBox>
        <ComboBox x:Name="ComboBox1" HorizontalAlignment="Left" ItemsSource="{Binding Items}" SelectedValue="{Binding SelectedValue, UpdateSourceTrigger=PropertyChanged}" Width="200"/>
        <Button x:Name="Button1" HorizontalAlignment="Left" Content="Save" Command="{Binding ClickCommand}" Width="116"/>
    </StackPanel>
</Window>
//
//
//ViewModel
public class MainViewModel : INotifyPropertyChanged
    {
        private IList<string> _items;
        private bool _canExecute;
        private ICommand _clickCommand;
        private string _textValue;
        private string _selectedValue;

        public IList<string> Items
        {
            get { return _items; }
        }

        public string SelectedValue
        {
            get { return _selectedValue; }
            set 
            { 
                _selectedValue = value;
                OnPropertyChanged("SelectedValue");
            }
        }
        public string TextValue
        {
            get { return _textValue; }
            set { 
                _textValue = value;
            OnPropertyChanged("TextValue");}
        }
        public void Save()
        {
            SelectedValue = _items.FirstOrDefault();
            TextValue = "Значение по умолчанию";
        }

        public ICommand ClickCommand
        {
            get { return _clickCommand ?? (new RelayCommand(() => Save(), _canExecute)); }
        }

        public MainViewModel()
        {
            _items = new List<string> { "Test1", "Test2", "Test3" };
            _selectedValue = _items.First();
            _textValue = "Значение по умолчанию";
            _canExecute = true;
        }


        public event PropertyChangedEventHandler PropertyChanged;

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

    public class RelayCommand : ICommand
    {
        private Action _action;
        private bool _canExecute;
        public RelayCommand(Action action, bool canExecute)
        {
            _action = action;
            _canExecute = canExecute;
        }

        public bool CanExecute(object parameter)
        {
            return _canExecute;
        }

        public event EventHandler CanExecuteChanged;

        public void Execute(object parameter)
        {
            _action();
        }
    }

Plus we need this:

private readonly MainViewModel _viewModel;
public MainWindow()
        {
            InitializeComponent();
            _viewModel = new MainViewModel();
            this.DataContext = _viewModel;
        }

Answer 3

In the event you want to stay on the same page but clear all fields, such as if the page's DataContext needs to created with parameters, you can simply add a method like this to the page or user control's ...xaml.cs file:

    private void Clear(object sender, RoutedEventArgs e)
    {
        this.DataContext = null;
    }