WPF - Observable Collection new record from xml binding - wpf

Question

I have a page with tabcontrol.
I am binding a list of locations a tabitem in the control.
The records are listed in a listview.
I am able to edit records by binding input controls to the listview.selecteditem.
My problem is when I want to add a new record. I want to minimise code behind.
ViewModel:
private ObservableCollection<LocationViewModel> _locations;
public ObservableCollection<LocationViewModel> Locations
{
get { return _locations; }
}
public LocationListViewModel()
{
_locations = new ObservableCollection<LocationViewModel>();
foreach (Service.Location l in service.GetLocationList().OrderBy(l => l.Building).ThenBy(l => l.Floor))
{
_locations.Add(new LocationViewModel
{
id = l.id,
Building = l.Building,
Floor = l.Floor,
RoomNo = l.RoomNo,
MapTitle = l.MapTitle,
MapExtension = l.MapExtension,
Map = l.Map,
DateCreated = l.DateCreated,
CreatedByID = l.CreatedByID,
CreatedByDesc = l.CreatedByDesc,
DateEdited = l.DateEdited,
EditedByID = l.EditedByID,
EditedByDesc = l.EditedByDesc
}
);
}
}
XML:
<TabItem x:Name="tabSettingsLocations" x:Uid="tabSettingsLocations"
Header="Locations"
DataContext="{StaticResource ResourceKey=LocationList}"> .....
Example of successful binding to listview for edits
<TextBox x:Name="txtSettingLocationBuildingEdit"
Margin="90,17,0,0" Style="{DynamicResource SettingsTextBoxStyle}"
Text="{Binding SelectedItem.Building, ElementName=lvwSettingsLocations,
Mode=TwoWay}" />
Example of unsuccessful binding for new record (uses different set of input controls)
<TextBox x:Name="txtSettingLocationBuildingAdd"
Margin="90,17,0,0" Style="{DynamicResource SettingsTextBoxStyle}"
Text="{Binding Building, ElementName=lvwSettingsLocations,
Mode=OneWayToSource}"/>
I also tried to bind the child tab item to the same data source
<TabItem x:Name="tbSettingsLocationsAdd" x:Uid="tbSettingsLocationsAdd"
Header="Add New"
DataContext="{StaticResource ResourceKey=LocationList}">
<TextBox x:Name="txtSettingLocationBuildingAdd"
Margin="90,17,0,0" Style="{DynamicResource SettingsTextBoxStyle}"
Text="{Binding Building}"/>
To no avail.
I also tried creating a new child dataview but I want it all to be bound together so that the interface updates whatever I do add or edit.
Anyone help?

Answer 1

Okay so I nailed this in the end. Just wanted to share ... thanks to Silvermind for a good tip on best practice.
Command:
class Location_Add : ICommand
{
private ObservableCollection<LocationViewModel> _llvm;
public ObservableCollection<LocationViewModel> llvm
{
get { return _llvm; }
}
public Location_Add(ObservableCollection<LocationViewModel> passedllvm)
{
_llvm = passedllvm;
}
public bool CanExecute(object parameter)
{
LocationViewModel lvw = parameter as LocationViewModel;
return lvw != null;
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
LocationViewModel lvm = parameter as LocationViewModel;
llvm.Add(lvm);
AddLocation(lvm);
}
public void RaiseCanExecuteChanged()
{
var handler = CanExecuteChanged;
if (handler != null)
{
handler(this, EventArgs.Empty);
}
}
public void AddLocation(LocationViewModel lvm)
{
try
{
Service.SchoolMonitorServiceClient service = new Service.SchoolMonitorServiceClient();
Service.Location loc = new Service.Location();
loc.Building = lvm.Building.Trim();
loc.Floor = lvm.Floor.Trim();
loc.RoomNo = lvm.RoomNo.Trim();
loc.MapTitle = lvm.MapTitle;
loc.MapExtension = lvm.MapTitle.Substring(lvm.MapTitle.IndexOf("."));
loc.Map = lvm.Map;
loc.DateCreated = DateTime.Now;
loc.CreatedByID = (Int32)Application.Current.Resources["UserID"];
loc.DateEdited = lvm.DateEdited;
service.AddLocation(loc);
MessageBox.Show("Your new Location was entered successfully", "Success", MessageBoxButton.OK);
}
catch (Exception e)
{
.....
}
}
}
ViewModel:
class LocationListViewModel
{
Service.SchoolMonitorServiceClient service = new Service.SchoolMonitorServiceClient();
#region Members
private ObservableCollection<LocationViewModel> _locations;
private Location_Add _AddCommand;
#endregion
#region Properties
public ObservableCollection<LocationViewModel> Locations
{
get { return _locations; }
}
#endregion
public LocationListViewModel()
{
_locations = new ObservableCollection<LocationViewModel>();
foreach (Service.Location l
in service.GetLocationList()
.OrderBy(l => l.Building).ThenBy(l => l.Floor))
{
_locations.Add(new LocationViewModel
{
id = l.id,
Building = l.Building,
Floor = l.Floor,
RoomNo = l.RoomNo,
MapTitle = l.MapTitle,
MapExtension = l.MapExtension,
Map = l.Map,
DateCreated = l.DateCreated,
CreatedByID = l.CreatedByID,
CreatedByDesc = l.CreatedByDesc,
DateEdited = l.DateEdited,
EditedByID = l.EditedByID,
EditedByDesc = l.EditedByDesc
}
);
}
_AddCommand = new Location_Add(_locations);
}
public ICommand AddCommand
{
get
{
return _AddCommand;
}
}
}
XML:
xmlns:local="clr-namespace:SchoolMonitor_WPF.ViewModels"
<Page.Resources>
<local:LocationListViewModel x:Key="LocationList" />
<local:LocationViewModel x:Key="NewLocation" />
</Page.Resources>
<TextBox x:Name="txtSettingLocationBuildingAdd" x:Uid="txtSettingLocationBuildingAdd"
Margin="90,17,0,0" Style="{DynamicResource SettingsTextBoxStyle}"
DataContext="{StaticResource ResourceKey=NewLocation}"
Text="{Binding Path=Building}"/>
<Button x:Name="btnSettingsLocationSaveAdd" Content="Submit" Margin="0,80,10,0"
VerticalAlignment="Top" Style="{DynamicResource ButtonStyle}"
HorizontalAlignment="Right" Width="75"
DataContext="{StaticResource ResourceKey=LocationList}"
CommandParameter="{StaticResource ResourceKey=NewLocation}"
Command="{Binding AddCommand}">
Hope this helps someone.