Calling a method on an instance of an object in WPF is not as easy to figure out, but with the help of this Internet thing I managed it.
Say you have a DataTemplate that renders a WorkItemType as a button that is selectable:
1 1: <DataTemplate DataType="{x:Type tfswitc:WorkItemType}">
1 2: <DockPanel>
1 3: <Image DockPanel.Dock="Left"
1 4: x:Name="wiImage"
1 5: Width="16"
1 6: Height="16"
1 7: Source="pack://application:,,/Resources/Images/WorkItems/unknown.gif">
1 8: </Image>
1 9: <Button x:Name="wiButton"
1 10: Content="{Binding Name}"
1 11: Style="{DynamicResource WelcomeButtonStyle}"
1 12: CommandParameter="{Binding}"
1 13: Command="Controlers:TeamSystemCommands.ChangeWorkItemTypeCommand">
1 14: </Button>
1 15: </DockPanel>
1 16: </DataTemplate>
Now, if I wanted to call a method on an instance of that WorkItemType and perform some action, then I would need a DataTrigger:
1 1: <DataTemplate DataType="{x:Type tfswitc:WorkItemType}">
1 2: <DockPanel>
1 3: <Image DockPanel.Dock="Left"
1 4: x:Name="wiImage"
1 5: Width="16"
1 6: Height="16"
1 7: Source="pack://application:,,/Resources/Images/WorkItems/unknown.gif">
1 8: </Image>
1 9: <Button x:Name="wiButton"
1 10: Content="{Binding Name}"
1 11: Style="{DynamicResource WelcomeButtonStyle}"
1 12: CommandParameter="{Binding}"
1 13: Command="Controlers:TeamSystemCommands.ChangeWorkItemTypeCommand">
1 14: </Button>
1 15: </DockPanel>
1 16: <DataTemplate.Triggers>
1 17: <DataTrigger Value="False">
1 18: <DataTrigger.Binding>
1 19: <Binding>
1 20: <Binding.Source>
1 21: <ObjectDataProvider ObjectType="{x:Type tfswitc:WorkItemType}"
1 22: MethodName="SupportedByHeat" />
1 23: </Binding.Source>
1 24: </Binding>
1 25: </DataTrigger.Binding>
1 26: <Setter TargetName="wiButton"
1 27: Property="IsEnabled"
1 28: Value="False" />
1 29: <Setter TargetName="wiButton"
1 30: Property="ToolTip"
1 31: Value="You will need to add the 'HeatITSM.Ref' field to use this work item." />
1 32: </DataTrigger>
1 33: </DataTemplate.Triggers>
1 34: </DataTemplate>
This will Call the method and if it returns false, it will disable the button and set a tooltip.
Now, this should work, but my SupportedByHeat method is an Extension method defined as:
1 1: Imports Microsoft.TeamFoundation.WorkItemTracking.Client
1 2:
1 3: Namespace TeamFoundationExtensions
1 4:
1 5:
1 6: Module WorkItemTypeExtensions
1 7:
1 8: <System.Runtime.CompilerServices.Extension()> _
1 9: Public Function SupportedByHeat(ByVal wit As WorkItemType) As Boolean
1 10: Dim c As Controlers.TeamSystemControler(Of MainWindow)
1 11: c = Application.ControlerFactory.GetControler(Of Controlers.TeamSystemControler(Of MainWindow))()
1 12: Return c.CheckWorkItemField(wit)
1 13: End Function
1 14:
1 15: End Module
1 16:
1 17: End Namespace
And this does not seam to work even if I import the namespace in the XAML:
1 1: <UserControl x:Class="SelectWorkItemType"
1 2: xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
1 3: xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
1 4: xmlns:d="http://schemas.microsoft.com/expression/blend/2006"
1 5: xmlns:tfs="clr-namespace:Microsoft.TeamFoundation.Client;assembly=Microsoft.TeamFoundation.Client"
1 6: xmlns:tfswitc="clr-namespace:Microsoft.TeamFoundation.WorkItemTracking.Client;assembly=Microsoft.TeamFoundation.WorkItemTracking.Client"
1 7: xmlns:tfse="clr-namespace:Hinshelwood.TFSHeatITSM.TeamFoundationExtensions"
1 8: xmlns:local="clr-namespace:Hinshelwood.TFSHeatITSM"
1 9: xmlns:Controlers="clr-namespace:Hinshelwood.TFSHeatITSM.Controlers"
1 10: xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
1 11: mc:Ignorable="d">
The error message that is received is:
System.Windows.Data Error: 34 : ObjectDataProvider: Failure trying to invoke method on type; Method=‘SupportedByHeat’; Type=‘WorkItemType’; Error=‘No method was found with matching parameter signature.’ MissingMethodException:‘System.MissingMethodException: Method ‘Microsoft.TeamFoundation.WorkItemTracking.Client.WorkItemType.SupportedByHeat’ not found.
at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams)_at System.Type.InvokeMember(String name, BindingFlags invokeAttr, Binder binder, Object target, Object[] args, CultureInfo culture)
at System.Windows.Data.ObjectDataProvider.InvokeMethodOnInstance(Exception& e)’_
As you can see, during the binding the extension method is not evaluated.
During my investigation I came across WPFix Part 3 (Extension Methods) that intoned that there is indeed some solution, but it is complicated requiring the use of Lambda expressions.
I am looking for an easy solution :)
No related videos found.
If you've made it this far, it's worth connecting with our principal consultant and coach, Martin Hinshelwood, for a 30-minute 'ask me anything' call.
We partner with businesses across diverse industries, including finance, insurance, healthcare, pharmaceuticals, technology, engineering, transportation, hospitality, entertainment, legal, government, and military sectors.
Higher Education Statistics Agency
Slaughter and May
Capita Secure Information Solutions Ltd
DFDS
Ericson
Alignment Healthcare
Epic Games
Schlumberger
Slicedbread
Bistech
Boeing
Workday
NIT A/S
Qualco
CR2
Cognizant Microsoft Business Group (MBG)
Kongsberg Maritime
ALS Life Sciences
Washington Department of Transport
Ghana Police Service
Department of Work and Pensions (UK)
Washington Department of Enterprise Services
Royal Air Force
Nottingham County Council
Flowmaster (a Mentor Graphics Company)
Illumina
MacDonald Humfrey (Automation) Ltd.
YearUp.org
Qualco
Cognizant Microsoft Business Group (MBG)