Using bound data in DataTemplate - wpf

Question

I have a CustomWindow.cs that I'm decorating using a DataTemplate, as there are a large number of content variations. As per MVVM, the window's DataContext is bound to a ViewModel
Ideally, some of these decorations would be populated using data from the ViewModel.
The structure I would like to achieve is something like the following:
<CustomWindow DataContext="{Binding Main, Source={StaticResource Locator}}">
<Content>
</CustomWindow>
The DataTemplate may look something like:
<DataTemplate DataType="{x:Type CustomWindow}">
<ContentPresenter Content="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type viewModels:HmiViewModelBase}}}">
<ContentPresenter Content="{Binding Content}"/>
</ContentPresenter>
</DataTemplate>
I realise that the double definition of Content in ContentPresenter wouldn't work but can't think of an alternative.
How would I achieve something like this?
I feel like this would be a common issue.

Answer 1

first of all welcome to SO. Please look at the next concept: 1) One main view model contains a number of models in some observable collection (or based on binding and properties). 2) Each model in observable collection has its own logic and is supposed to be presented in some original way. 3) The main view model is presented by main view (let say list box).
4) Each mode inside the observable collection of the main view model is presented by content control which will select some original content template for its content (which is a model inside the observable collection). 5)Data template based on the model type can use every wpf control (or user custom control you made) and present data. Here is the code:
1. XAML code:
<Window x:Class="DataTemplateSOHelpAttempt.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:dataTemplateSoHelpAttempt="clr-namespace:DataTemplateSOHelpAttempt"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<dataTemplateSoHelpAttempt:MainViewModel/>
</Window.DataContext>
<Window.Resources>
<DataTemplate DataType="{x:Type dataTemplateSoHelpAttempt:OrangeObject}">
<TextBlock Text="{Binding Description}" Background="Orange"></TextBlock>
</DataTemplate>
<DataTemplate DataType="{x:Type dataTemplateSoHelpAttempt:GreenObject}">
<TextBlock Text="{Binding Description}" Background="GreenYellow"></TextBlock>
</DataTemplate>
<DataTemplate DataType="{x:Type dataTemplateSoHelpAttempt:BlueObject}">
<TextBlock Text="{Binding Description}" Background="CadetBlue"></TextBlock>
</DataTemplate>
</Window.Resources>
<Grid>
<ListBox ItemsSource="{Binding Objects}">
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Setter Property="ContentTemplate">
<Setter.Value>
<DataTemplate>
<ContentControl Content="{Binding }"/>
</DataTemplate>
</Setter.Value>
</Setter>
</Style>
</ListBox.ItemContainerStyle>
</ListBox>
</Grid></Window>
2. View model code:
public class MainViewModel:BaseObservableObject
{
public MainViewModel()
{
Objects = new ObservableCollection<BaseDataObject>(new List<BaseDataObject>
{
new BlueObject{Description = "Hello I'm blue object!!!"},
new OrangeObject{Description = "Hello I'm orange object!!!"},
new GreenObject{Description = "Hello I'm green object!!!"},
new OrangeObject{Description = "Hello I'm anoter orange object!!!"},
new BlueObject{Description = "Hello I'm another blue object!!!"},
new OrangeObject{Description = "Hello I'm another orange again object!!!"},
new GreenObject{Description = "Hello I'm another green object!!!"},
new OrangeObject{Description = "Hello I'm again another orange object!!!"},
});
}
public ObservableCollection<BaseDataObject> Objects { get; set; }
}
3. Models Code:
public abstract class BaseDataObject:BaseObservableObject
{
public abstract string Description { get; set; }
}
public class OrangeObject:BaseDataObject
{
private string _description;
public override string Description
{
get { return _description; }
set
{
_description = value;
OnPropertyChanged();
}
}
}
public class BlueObject:BaseDataObject
{
private string _description;
public override string Description
{
get { return _description; }
set
{
_description = value;
OnPropertyChanged();
}
}
}
public class GreenObject:BaseDataObject
{
private string _description;
public override string Description
{
get { return _description; }
set
{
_description = value;
OnPropertyChanged();
}
}
}
4. Basic INotifyPropertyChanged implementation (use 4.5 dotNet version for CallerMemberName):
public class BaseObservableObject : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
var handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
protected virtual void OnPropertyChanged<T>(Expression<Func<T>> raiser)
{
var propName = ((MemberExpression)raiser.Body).Member.Name;
OnPropertyChanged(propName);
}
protected bool Set<T>(ref T field, T value, [CallerMemberName] string name = null)
{
if (!EqualityComparer<T>.Default.Equals(field, value))
{
field = value;
OnPropertyChanged(name);
return true;
}
return false;
}
}
That's all, copy/past, debug and use. I'll be glad to help if you will have problems with the code. Please mark it as answered if the answer was helpful.
Regards,