CODEWITHSUNDEEP
c#wpfmvvmmvvm-light
Eldho
Eldho

Reputation: 8273

Notify Collection changed across viewmodels

I have a scenario that Main-window has content control i switch user control of particular view through it and have View-Models respectively

In one of my User-Control has another user-control in it. Both have a View-Model

<UserControl DataContext="ViewModel1">

<Grid>

 <ListView ItemsSource="{Binding TimeSlotCollection}"  <!--This Collection is in ViewModel 1-->
                  ">
  </ListView>

  <UserControl DataContext="ViewModel2">
      <DataGrid x:Name="DataGrid" 
              CanUserAddRows="True"                 
              ItemsSource="{Binding TimeSlotCollection,Mode=TwoWay,
              UpdateSourceTrigger=PropertyChanged}"/>  <!--This Collection is in ViewModel 2-->
 </Grid>

</UserControl>

I want Notify the View-model 1 Collection when View-model 2 Collection is Changed

MyViewModel 1

    private ObservableCollection<AttendanceTimeSlotModel> _timeslotCollection;

    public ObservableCollection<AttendanceTimeSlotModel> TimeSlotCollection
    {
        get { return _timeslotCollection; }
        set
        {
            Set(TimeSlotCollectionPropertyName, ref _timeslotCollection, value);
        }
    }



    public const string EmployeesCollectionPropertyName = "Employees";

    private ObservableCollection<EmployeeModel> _employees;

    public ObservableCollection<EmployeeModel> Employees
    {
        get { return _employees; }
        set
        {
            Set(EmployeesCollectionPropertyName, ref _employees, value);
        }
    }


    public const string IsBusyPropertyName = "IsBusy";

    private bool _isBusy = false;
    public bool IsBusy
    {
        get
        {
            return _isBusy;
        }
        set
        {
            Set(IsBusyPropertyName, ref _isBusy, value);
        }
    }

MyViewModel 2

    public const string AttendanceTimeSlotCollectionPropertyName = "TimeSlotCollection";

    private ObservableCollection<AttendanceTimeSlotModel> _timeSlotCollection = null;

    public ObservableCollection<AttendanceTimeSlotModel> TimeSlotCollection
    {
        get
        {
            return _timeSlotCollection;
        }
        set
        {
            Set(AttendanceTimeSlotCollectionPropertyName, ref _timeSlotCollection, value);
        }
    } 

    /// What i trying 
     public void AddNewTimeSlot(AttendanceTimeSlotModel timeSlot)
    {


        _designdataService.InsertTimeSlot(timeSlot);
        var Vm = SimpleIoc.Default.GetInstance<ViewModels.AssignTimeSlotViewModel>();
        RaisePropertyChanged(Vm.TimeSlotCollection);
    }

What i'm trying to achieve when my collection inside View-model 2 is updated i want to notify in View-model 1.

Upvotes: 0

Views: 627

Answers (1)

Sheridan
Sheridan

Reputation: 69959

When using MVVM, I like to use just one view model to one view. If you simply take your inner UserControl to be part of its parent UserControl, then you'll only need one view model. Try re-arranging your code like this:

<UserControl DataContext="ViewModel1">
    <Grid>    
        <ListView ItemsSource="{Binding TimeSlotCollection}" />
        <UserControl DataContext="{Binding TimeSlotCollection}">
            ... 
            <!-- Then inside the inner control -->
            <DataGrid x:Name="DataGrid" ItemsSource="{Binding}" ... />
            ...
        </UserControl>
    </Grid>
</UserControl>

In this way, you just have to manage the one collection in the one view model and most of your problems will just disappear.

Upvotes: 2

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