This might be simple for you guys but am just starting in WPF, and always my mind thinks in terms of Winforms, and am wrong all the time.
Anyway here is my situation. I have label in my view like below:
UserControl
<UserControl.Resources>
<Converters:BooleanToVisibilityConverter x:Key="visibilityConverter"></Converters:BooleanToVisibilityConverter>
<!-- Error Handling -->
<Converters:BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
<Converters:ErrorConverter x:Key="errorConverter"/>
<ControlTemplate x:Key="ErrorTemplate">
<Border BorderBrush="Red" BorderThickness="2">
<AdornedElementPlaceholder />
</Border>
</ControlTemplate>
<Style x:Key="textBoxInError" TargetType="{x:Type TextBox}">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors), Converter={StaticResource errorConverter}}"/>
</Trigger>
</Style.Triggers>
</Style>
<Style x:Key="comboBoxInError" TargetType="{x:Type ComboBox}">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="true">
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors), Converter={StaticResource errorConverter}}"/>
</Trigger>
</Style.Triggers>
</Style>
</UserControl.Resources>
Label
<Label Name="IsImageValid" Content="Image Created" Margin="0,7,-1,0" Style="{StaticResource LabelField}"
Grid.ColumnSpan="2" Grid.Row="15" Width="90" Height="28" Grid.RowSpan="2"
Grid.Column="1" IsEnabled="True"
Visibility="{Binding IsImageValid,Converter={StaticResource BooleanToVisibilityConverter}}" />
I am trying to call the this label in my view model but not sure how.
I have t following method in the viewmodel, planning to use the label to display some message based on the condition like below.
ViewModel
public class MetadataViewModel : NotificationObject, IMetadataViewModel
{
#region :: Properties ::
private IEventAggregator eventAggregator;
private IImageResizerService imageResizer;
private string headerInfo;
public string HeaderInfo
{
get
{
return headerInfo;
}
set
{
if (this.headerInfo != value)
{
this.headerInfo = value;
this.RaisePropertyChanged(() => this.HeaderInfo);
}
}
}
public ICommand SaveCommand
{
get;
private set;
}
public ICommand CloseCommand
{
get;
private set;
}
public ICommand DeleteCommand
{
get;
private set;
}
public ICommand SubmitCommand
{
get;
private set;
}
public ICommand UnSubmitCommand
{
get;
private set;
}
public ICommand LocationSearchCommand
{
get;
private set;
}
public ICommand SubjectSearchCommand
{
get;
private set;
}
public ICommand RemoveLocationCommand
{
get;
private set;
}
public ICommand RemoveSubjectCommand
{
get;
private set;
}
private StoryItem selectedStory;
public StoryItem SelectedStory
{
get
{
return this.selectedStory;
}
set
{
if (this.selectedStory != value)
{
this.selectedStory = value;
this.RaisePropertyChanged(() => this.SelectedStory);
// raise dependencies
this.RaisePropertyChanged(() => this.CanSave);
this.RaisePropertyChanged(() => this.CanUnSubmit);
this.RaisePropertyChanged(() => this.CanDelete);
}
}
}
public List<Program> ProgramList
{
get;
private set;
}
public List<Genre> GenreList
{
get;
private set;
}
public List<Copyright> CopyrightList
{
get;
private set;
}
public bool CanSave
{
get
{
bool canSave = false;
if (this.SelectedStory.IsLockAvailable)
{
if (!this.SelectedStory.Submitted)
{
canSave = true;
}
}
return canSave;
}
}
public bool CanDelete
{
get
{
bool canDelete = false;
if (this.SelectedStory.IsLockAvailable)
{
if (!this.SelectedStory.Submitted)
{
canDelete = true;
}
}
return canDelete;
}
}
public bool CanUnSubmit
{
get
{
bool canUnSubmit = false;
if (this.SelectedStory.IsLockAvailable)
{
if (this.SelectedStory.Submitted)
{
canUnSubmit = true;
}
}
return canUnSubmit;
}
}
#endregion
#region :: Contructor ::
[ImportingConstructor]
public MetadataViewModel(
IMetadataController metadataController,
IGatewayService gateway,
INavigationService navigator,
IImageResizerService imageResizer,
IEventAggregator eventAggregator
)
{
this.eventAggregator = eventAggregator;
this.imageResizer = imageResizer;
// populate drop-down lists
this.ProgramList = gateway.GetPrograms(true);
this.GenreList = gateway.GetGenres();
this.CopyrightList = gateway.GetCopyrights();
// add dummy values so the user can de-select
this.ProgramList.Add(new Program());
this.GenreList.Add(new Genre());
this.CopyrightList.Add(new Copyright());
// commands
this.SaveCommand = metadataController.SaveCommand;
this.CloseCommand = metadataController.CloseCommand;
this.DeleteCommand = metadataController.DeleteCommand;
this.SubmitCommand = metadataController.SubmitCommand;
this.UnSubmitCommand = metadataController.UnSubmitCommand;
this.LocationSearchCommand = new DelegateCommand<string>(this.LocationSearch);
this.SubjectSearchCommand = new DelegateCommand<string>(this.SubjectSearch);
this.RemoveLocationCommand = new DelegateCommand<Topic>(this.RemoveLocation);
this.RemoveSubjectCommand = new DelegateCommand<Topic>(this.RemoveSubject);
// events
this.eventAggregator.GetEvent<StorySelectedEvent>().Subscribe(OnStorySelected, ThreadOption.UIThread);
this.eventAggregator.GetEvent<AddLocationEvent>().Subscribe(OnAddLocation, ThreadOption.UIThread);
this.eventAggregator.GetEvent<AddSubjectEvent>().Subscribe(OnAddSubject, ThreadOption.UIThread);
this.eventAggregator.GetEvent<CommandCompletedEvent>().Subscribe(OnCommandCompleted, ThreadOption.UIThread);
this.eventAggregator.GetEvent<ImageResizeCompletedEvent>().Subscribe(OnImageResizeCompleted, ThreadOption.UIThread);
this.Initialize();
}
#endregion
private void OnStorySelected(StoryItem selectedStory)
{
if (this.selectedStory != null)
{
this.Initialize();
// override the initialized values
this.SelectedStory = selectedStory;
this.SelectedStory.HaveChanged = false;
this.HeaderInfo = "Edit";
}
}
public void OnAddLocation(Topic topic)
{
if (topic != null)
{
if (!this.SelectedStory.Locations.Contains(topic))
{
this.SelectedStory.Locations.Add(topic);
this.RaisePropertyChanged(() => this.SelectedStory.Locations);
}
}
}
public void OnAddSubject(Topic topic)
{
if (topic != null)
{
if (!this.SelectedStory.Subjects.Contains(topic))
{
this.SelectedStory.Subjects.Add(topic);
this.RaisePropertyChanged(() => this.SelectedStory.Subjects);
}
}
}
private void OnCommandCompleted(string commandType)
{
if (commandType == CommandTypes.MetadataEntry)
{
this.Initialize();
}
}
private void OnImageResizeCompleted(bool isSuccessful)
{
IsImageValid = false;
if (isSuccessful)
{
this.SelectedStory.KeyframeImages = true;
IsImageValid = true;
}
else
{
this.SelectedStory.KeyframeImages = false;
IsImageValid=false;
}
}
private void Initialize()
{
this.SelectedStory = new StoryItem();
this.HeaderInfo = "Create";
}
private void LocationSearch(object topicType)
{
this.eventAggregator.GetEvent<LocationSearchEvent>().Publish(null);
}
private void SubjectSearch(object topicType)
{
this.eventAggregator.GetEvent<SubjectSearchEvent>().Publish(null);
}
private void RemoveLocation(Topic selected)
{
if (selected != null)
{
// remove the primary too
if (this.SelectedStory.PrimaryLocation != null)
{
if (string.Equals(this.SelectedStory.PrimaryLocation.FullName, selected.FullName, StringComparison.InvariantCultureIgnoreCase))
{
this.SelectedStory.PrimaryLocation = new Topic();
}
}
bool isSuccessful = this.SelectedStory.Locations.Remove(selected);
if (isSuccessful)
{
this.RaisePropertyChanged(() => this.SelectedStory.Locations);
}
}
}
private void RemoveSubject(Topic selected)
{
if (selected != null)
{
// remove the primary too
if (this.SelectedStory.PrimarySubject != null)
{
if (string.Equals(this.SelectedStory.PrimarySubject.FullName, selected.FullName, StringComparison.InvariantCultureIgnoreCase))
{
this.SelectedStory.PrimarySubject = new Topic();
}
}
bool isSuccessful = this.SelectedStory.Subjects.Remove(selected);
if (isSuccessful)
{
this.RaisePropertyChanged(() => this.SelectedStory.Subjects);
}
}
}
}
private booly _isImageValid;
public bool IsImageValid
{
get
{
return _isImageValid;
}
set
{
_isImageValid = value;
this.RaisePropertyChanged(() => this.IsImageValid);
}
}
}
Honestly i don’t know how view will understand the binding.
A standard approach is to have a boolean property like “IsImageValid” in your ViewModel…Then in your XAML, bind the Visibility property of your label to that property, with a BooleanToVisibilityConverter http://msdn.microsoft.com/en-us/library/system.windows.controls.booleantovisibilityconverter.aspx