change data grid based on combobox selection WPF - wpf

Question

I am trying to populate a datagrid based on the selection from a combobox, I am new to wpf so I am not sure if my issue is the the databinding or what. Here is my VM:
namespace WasteTracker
{
public class MenuItemViewModel : INotifyPropertyChanged
{
DataSource data = new DataSource();
private ObservableCollection<StationList> stationlistcb = new
ObservableCollection<StationList>();
private ObservableCollection<MenuItem> menuitemdg = new
ObservableCollection<MenuItem>();
//methods to populate combobox of stations and datagrid of menu items
for that station
#region Load Stations and Menu Methods
public void LoadStationList()
{
stationlistcb = new ObservableCollection<StationList>
(data.Stations());
}
public void LoadMenuItems(int stationid)
{
menuitemdg = new ObservableCollection<MenuItem>
(from onemenuitem in data.MenuItems()
where onemenuitem.StationId.Equals(stationid)
select onemenuitem);
OnPropertyChanged("MenuItemData");
}
#endregion
public ObservableCollection<StationList> StationList
{
get
{
return stationlistcb;
}
}
public ObservableCollection<MenuItem> MenuItemList
{
get
{
return menuitemdg;
}
}
/// <summary>
/// Called when [property changed].
/// </summary>
/// <param name="PropertyName">Name of the property.</param>
protected void OnPropertyChanged(string PropertyName)
{
VerifyPropertyName(PropertyName);
if (PropertyChanged != null)
{
PropertyChanged(this, new
PropertyChangedEventArgs(PropertyName));
}
}
#region Propertychange Methods
/// <summary>
/// Warns the developer if this object does not have
/// a public property with the specified name. This
/// method does not exist in a Release build.
/// </summary>
[Conditional("DEBUG")]
[DebuggerStepThrough]
private void VerifyPropertyName(string propertyName)
{
// Verify that the property name matches a real,
// public, instance property on this object.
if (TypeDescriptor.GetProperties(this)[propertyName] == null)
{
string msg = "Invalid property name: " + propertyName;
throw new Exception(msg);
}
}
#endregion
public event PropertyChangedEventHandler PropertyChanged;
}
}
And here is the XAML for the page:
<TextBlock Grid.Row="0" Grid.ColumnSpan="3" FontSize="35"
HorizontalAlignment="Center" VerticalAlignment="Top" Text="Microsoft
SVMT Waste Tracker" Height="50" Width="480" Margin="44,0" />
<TextBlock Grid.Row="1" Grid.ColumnSpan="3" FontSize="30"
HorizontalAlignment="Center" VerticalAlignment="Top" Text="Waste
Entry" Height="50" Width="166" Margin="10,0,44,0" />
<TextBlock Grid.Row="2" Grid.Column="0" Text="Station" FontSize="30"
HorizontalAlignment="Center" VerticalAlignment="top" />
<TextBlock Grid.Row="2" Grid.Column="3" Text="Date" FontSize="30"
HorizontalAlignment="Center" VerticalAlignment="top" />
<DatePicker Grid.Row="3" Grid.Column="2" Grid.RowSpan="2" FontSize="30"
HorizontalAlignment="Center" VerticalAlignment="Center"
Width="290" Height="42" Margin="0,19,10,22" />
<ComboBox Name="StationBox" Grid.Row="3" Grid.Column="0"
Grid.RowSpan="2" FontSize="30" ItemsSource="{Binding StationList}"
DisplayMemberPath="StationName" HorizontalAlignment="Center"
VerticalAlignment="Center" Width="300" Height="42"
Margin="0,19,0,23"
SelectionChanged="Station_SelectionChanged" />
<DataGrid ItemsSource="{Binding MenuItemList}"
DisplayMemberPath="MenuItemText" AutoGenerateColumns="False"
Grid.Row="5" Grid.ColumnSpan="3" CanUserAddRows="True"
AlternatingRowBackground="AliceBlue"
IsSynchronizedWithCurrentItem="True" >
<DataGrid.Columns>
<DataGridTextColumn Header="Menu Item" Binding="{Binding
MenuItemText}" HeaderStyle="{StaticResource CenterGridHeader}"
CellStyle="{StaticResource CenterCellText}"
IsReadOnly="True" CanUserResize="False"
FontSize="36" Width="*"/>
<DataGridTextColumn Header="UoM" Binding="{Binding UoM}"
HeaderStyle="{StaticResource CenterGridHeader}" CellStyle="
{StaticResource CenterCellText}"
IsReadOnly="True" FontSize="36"
CanUserResize="False" Width="*" />
<DataGridTextColumn Header="Left Over" Binding="{Binding
UserInput}" HeaderStyle="{StaticResource CenterGridHeader}"
CellStyle="{StaticResource CenterCellText}"
FontSize="36" IsReadOnly="False"
CanUserResize="False" Width="*"/>
<DataGridTextColumn Header="UoM" Binding="{Binding UoM}"
HeaderStyle="{StaticResource CenterGridHeader}" CellStyle="
{StaticResource CenterCellText}"
IsReadOnly="True" FontSize="36"
CanUserResize="False" Width="*" />
<DataGridTextColumn Header="Par" Binding="{Binding Par}"
HeaderStyle="{StaticResource CenterGridHeader}" CellStyle="
{StaticResource CenterCellText}"
IsReadOnly="True" FontSize="36"
CanUserResize="False" Width="*"/>
<DataGridTextColumn Header="UoM" Binding="{Binding UoM}"
HeaderStyle="{StaticResource CenterGridHeader}" CellStyle="
{StaticResource CenterCellText}"
IsReadOnly="True" FontSize="36"
CanUserResize="False" Width="*" />
</DataGrid.Columns>
</DataGrid>
</Grid>
this is the xaml.cs:
public MenuItemViewModel _objViewModel = new MenuItemViewModel();
public EnterWaste()
{
InitializeComponent();
SourceContext();
InitialOperations();
}
private void Station_SelectionChanged(object sender,
SelectionChangedEventArgs e)
{
_objViewModel.LoadMenuItems((StationBox.SelectedItem as
MenuItem).StationId);
}
With this code currently the combobox is currently populated with the correct info, however when I make a selection from the combobox the datagrid will not display the correct info. Being new to wpf I have done a lot googling however the closest thing I can find in cascading comboboxes, and that solution really didn't help. Any suggestions would be appreciated.