WPF: DataTemplate and UserControl map not working

Question

I'm starting a WPF project. Trying to binding usercontrol by viewmodel. Where viewmodel define with dataType at DataTemplate in Application.Reousrces. But user control not bind. Any one can help me?

    <Application.Resources>
        <DataTemplate DataType="{x:Type vm:MatterPanelViewModel}">
            <uc:MatterPanel />
        </DataTemplate>
    </Application.Resources>

Main Window where will bind user control.

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:uc="clr-namespace:MyProject"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
        mc:Ignorable="d" x:Class="MyProject.MainWindow"
        Title="MyProject" WindowState="Maximized" d:DataContext="{d:DesignInstance Type=uc:MainWindowViewModel}">

    <Grid Grid.Row="2">
         <ContentControl Content="{Binding CurrentViewModel}" Margin="10,0,10,10" />
    </Grid>
</Window>

CurrentViewModel is the property of MainViewModel.

public class MainWindowViewModel:ViewModelBase
{
 private ViewModelBase _currentViewModel;
        public ViewModelBase CurrentViewModel
        {
            get { return this._currentViewModel; }
            set
            {
                if(this._currentViewModel == value) { return; }
                this._currentViewModel = value;
                this.NotifyOfPropertyChange(() => this.CurrentViewModel);
            }
        }

    public MatterPanelViewModel MatterPanelViewModel { get; set; }
public MainWindowViewModel()
        {
            this.MatterPanelViewModel = ServiceLocator.Current.GetService<MatterPanelViewModel>();
        }
}



 public class MatterPanelViewModel:ViewModelBase
        {
            public MatterPanelViewModel()
            {

            }
        }

ViewModelBase here,

public class ViewModelBase : INotifyPropertyChanged
    {
        public event PropertyChangedEventHandler PropertyChanged
        {
            add { this._propertyChanged += value; }
            remove { this._propertyChanged -= value; }
        }

        private event PropertyChangedEventHandler _propertyChanged = delegate{ };

        protected void NotifyOfPropertyChange<T>(Expression<Func<T>> property)
        {
            var lambda = (LambdaExpression)property;
            MemberExpression memberExpression;
            if(lambda.Body is UnaryExpression)
            {
                var unaryExpression = (UnaryExpression)lambda.Body;
                memberExpression = (MemberExpression)unaryExpression.Operand;
            }
            else
            {
                memberExpression = (MemberExpression)lambda.Body;
            }
            this.NotifyOfPropertyChange(memberExpression.Member.Name);
        }
        public void NotifyOfPropertyChange(string property)
        {
            this.RaisePropertyChanged(property, true);
        }
        private void RaisePropertyChanged(string property, bool verifyProperty)
        {
            var handler = this._propertyChanged;
            if(handler != null)
            {
                handler(this, new PropertyChangedEventArgs(property));
            }
        }
    }

This is only the DataTemplate, and it looks fine. You'll need to also provide us with your view model code along with the XAML control that's hosting it so we can see the binding. — Mark Feldman
are you getting any errors in the output window for this user control? — Shivani Katukota

Md. Abdul Alim Md. Abdul Alim · Accepted Answer · 2018-07-26T07:39:12

Finally I solve the problem. The viewmodel and usercontrol map should under the MainWindow but here under main app. I just code from main app

<Application.Resources>
        <DataTemplate DataType="{x:Type vm:MatterPanelViewModel}">
            <uc:MatterPanel />
        </DataTemplate>
    </Application.Resources>

to Main Window

<Window.Resources>
        <BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter"/>
        <DataTemplate DataType="{x:Type vm:MatterPanelViewModel}">
            <usc:MatterPanel/>
        </DataTemplate>
    </Window.Resources>

Then its working well.

WPF: DataTemplate and UserControl map not working

1 Answers