Question

Question may need to be edited since I don’t think I necessarily know the best way to do this.

Current config of my WPF usercontrol.
I have a XmlDataProvider that contains some static XML Elements that I use to populate a TreeView control.
I currently use a HierarchicalDataTemplate to bind to a TreeViewItem

    <HierarchicalDataTemplate x:Key="SiteTemplate" ItemsSource="{Binding XPath=pci}">
        <TextBlock Text="{Binding XPath=@Name}"/>
    </HierarchicalDataTemplate>
    <Style TargetType="TreeViewItem">
        <Setter Property="IsExpanded" Value="True"/>
    </Style>

TreeView control

 <TreeView ItemsSource="{Binding Source={StaticResource SharePointSites}}" 
                              ItemTemplate="{StaticResource SiteTemplate}" 

I would like to replace the current static resource with data that is loaded from a xml file at runtime. Additionally I want the user to be able to modify the nodes of the treeview at runtime and have those values written back to the same xml file.
I have been reading up about using the MVVM pattern and creating an IObservable class. Can someone point me in the right direction?

Edit:
Perhaps I’ve asked this question in a sub-optimal way. Can anyone recommend improvements or make edits to improve the quality of the question in anyway?

Answer 1

I have no access to my Visual Studio environment so the code below will be full of compilation errors… So please treate this as a pseudo code…

Assuming your Xml structure is something like this….

<MyItem Name="Root"> 
    <MyItem Name="ABC"/> 
    <MyItem Name="PQR"> 
        <MyItem Name="IJK"/> 
    </MyItem> 
    <MyItem Name="XYZ"/> 
</MyItem> 

1. Bind your ItemsSource thru a converter , say MyXmlToObjectDataSourceConverter.

   <TreeView ItemsSource="{Binding Source={StaticResource SharePointSites},
          Converter={StaticResource MyXmlToObjectDataSourceConverter}}" ... />
   

2. In MyXmlToObjectDataSourceConverter.Convert() method return this…

   public object Convert(...) 
   { 
       return new ObservableCollection<XmlNodeWrapper>(
           ((XmlDataProvider)value).Document.SelectNodes("MyItem").Select( 
               d => new XmlNodeWrapper(d)).ToList()) 
   }
   

3. XmlNodeWrapper class will maintain the ‘node’ internally so that when updates take place thru property Setters,
   you can update the node based attribute back… like this…

   public class XmlNodeWrapper : INotifyPropertyChanged
   { 
       private XmlNode node; 
       private ObservableCollection<XmlNodeWrapper> children; 
   
       public XmlNodeWrapper(XmlNode node) 
       { 
           this.node = node; 
       } 
   
       public ObservaleCollection<XmlNodeWrapper> Children 
       { 
           get 
           { 
               if (children == null) 
               { 
                   this.children 
                       = new ObservableCollection<XmlNodeWrapper>( 
                           this.node.ChildNodes.Select( 
                               d => new XmlNodeWrapper(d)).ToList()); 
               } 
   
               return children; 
           } 
       } 
   
       public string Name 
       { 
           get 
           { 
               return node.Attributes["Name"]; 
           } 
   
           set 
           { 
               node.Attributes["Name"] = value; 
               this.PropertyChanged["Name"]; 
           } 
       } 
   
       public event PropertyChangedEventHandler PropertyChanged; 
   
       private void PropertyChanged(String info) 
       { 
           if (PropertyChanged != null) 
           { 
               PropertyChanged(this, new PropertyChangedEventArgs(info)); 
           } 
       }
   } 
   

4. Then replace all XPath attributes in your XAML with standard Path.

   <HierarchicalDataTemplate x:Key="SiteTemplate"
       ItemsSource="{Binding Path=Children}"> 
           <TextBlock Text="{Binding Path=Name}"/> 
   </HierarchicalDataTemplate>