Question

I have made a tree View in wpf Using MVVM .

it is working fine but here is one problem that leaf node contains some checkboxes and user have only two options either to select one or none .

So here how i can restricted user to select maximum only one cold drink.

I did one trick but it didn’t work that when i have already selected a drink and then i select another one than i set the last selected value in the observable collection to false but it doesn’t affect on view and selected check boxes remains selected although in collection only one option’s value is true.

I cant use radio button instedof checkbox becasue user can select none of the options and i cant give an additional option for none of the above.

If any one have any solution so please let me know I’ll be very thankful.

updated question:
i think i didn’t define my problem in a proper way so i am giving my code snipperts here hope by this i’ll get the solution o f my problem…

My View Model Class

namespace TestViewModels
{
 public class ViewModel :ViewModelBase

{

    private ObservableCollection<AvailableProducts> _MyTreeViewProperty

    public ObservableCollection<AvailableProducts> MyTreeViewProperty
    {
        get { return _MyTreeViewProperty
        set { _MyTreeViewProperty value; 
        RaisePropertyChanged("MyTreeViewProperty");}
    }

}

public class AvailableProducts

{

     private string _BrandName;

    public string BrandName
    {
        get { return _BrandName
        set { _BrandName = value; }
    }


    private bool _IsExpanded;
    public bool IsExpanded
    {
        get
        {
            return _IsExpanded;

        }
        set
        {
            _IsExpanded = value;

        }
    }

    private ObservableCollection<ProductTypes> _MyProductTypes

    public ObservableCollection<ProductTypes> MyProductTypes
    {
        get { return _MyProductTypes}
        set { _MyProductTypes= value; }
    }


}

public class ProductTypes
{
    private string _ProductTypeName;

    public string ProductTypeName
    {
        get { return _ProductTypeName;
        set { _ProductTypeNamevalue; }
    }



    private ObservableCollection<ProductSubTypes> _ProdSubTypes;

    public ObservableCollection<ProductSubTypes> ProdSubTypes
    {
        get { return _ProdSubTypes;}
        set { _ProdSubTypes;= value; }
    }


}


public class ProductSubTypes
{
    private string _ProductSubTypeName;

    public string ProductSubTypeName
    {
        get { return _ProductSubTypeName;
        set { _ProductSubTypeName;}
    }

    private int _ParentID;

    public int ParentID
    {
        get { return _ParentID;}
        set { _ParentID;= value; }
    }


    private bool _IsAssigned;

    public bool IsAssigned
    {
        get { return _IsAssigned; }
        set
        {
            _IsAssigned = value;

            if _ParentID;!= 0)
            {
               //updating data in database
               //Calling and setting new collection value in property

              //issue : updated collection sets in setter of MyTreeViewProperty but before calling getter
            // it comes to IsAssigned getter so view doesnt get updated  collection of MyTreeViewProperty 

            }
            RaisePropertyChanged("IsAssigned");
        }
    }


}

}

View

<Page x:Class="ShiftManagerViews.Pages.ProductTreeSelection
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"  
  DataContext="{Binding ProductsTree, Source={StaticResource Locator}}"
  mc:Ignorable="d"  Width="870" Height="665"

>

     <TreeView  Margin="10,10,0,13" ItemsSource="{Binding MyTreeViewProperty, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"  HorizontalAlignment="Left"

VerticalAlignment="Top" Width="800" Height="Auto" MinHeight="400" MaxHeight="800">
                <TreeView.ItemContainerStyle>

                    <Style TargetType="{x:Type TreeViewItem}">
                        <Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
                     </Style>
                </TreeView.ItemContainerStyle>

                <TreeView.Resources>

                        <HierarchicalDataTemplate DataType="{x:Type local:AvailableProducts}"
                                      ItemsSource="{Binding MyProductTypes}"> 
                        <WrapPanel>
                            <Image Width="20" Height="20" Source="/ShiftManagerViews;component/Images/12.bmp"/>
                            <Label Content="{Binding BrandName}" FontSize="14"/>
                        </WrapPanel>
                    </HierarchicalDataTemplate>

                        <HierarchicalDataTemplate DataType="{x:Type local:ProductTypes}"
                                      ItemsSource="{Binding ProdSubTypes}">
                        <WrapPanel>
                            <Image Width="18" Height="15" Source="/ShiftManagerViews;component/Images/12.bmp"/>
                            <Label Content="{Binding ProductTypeName}" FontSize="13"/>
                        </WrapPanel>
                    </HierarchicalDataTemplate>
                        <!-- the template for showing the Leaf node's properties-->
                        <DataTemplate DataType="{x:Type local:ProductSubTypes}">
                            <StackPanel>

                                <CheckBox IsChecked="{Binding IsAssigned, Mode=TwoWay}" Content="{Binding ProductSubTypeName}" Height="25">

                            </CheckBox>
                            </StackPanel>
                        </DataTemplate>
                    </TreeView.Resources>
                </TreeView>

Answer 1

Finally i am succeeded to solve my problem.

on Is Assigned property i am updating my database values and calling a method in view using MVVM Light messaging and passing currently selected leaf’s parent id in it as a parameter…

Added a property in class Product Types to expand the parent node of the last selected leaf..

In view’s method i am refreshing data context’s source and passing currently selected leaf’s parent id tO the VM to set its Is Expanded property value to true…

By this my view is working perfectly as same as i want…
If any body have solution better than this than I’ll be happy to know.