3 minute read
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: <DataTemplate DataType="{x:Type tfswitc:WorkItemType}">
2: <DockPanel>
3: <Image DockPanel.Dock="Left"
4: x:Name="wiImage"
5: Width="16"
6: Height="16"
7: Source="pack://application:,,/Resources/Images/WorkItems/unknown.gif">
8: </Image>
9: <Button x:Name="wiButton"
10: Content="{Binding Name}"
11: Style="{DynamicResource WelcomeButtonStyle}"
12: CommandParameter="{Binding}"
13: Command="Controlers:TeamSystemCommands.ChangeWorkItemTypeCommand">
14: </Button>
15: </DockPanel>
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: <DataTemplate DataType="{x:Type tfswitc:WorkItemType}">
2: <DockPanel>
3: <Image DockPanel.Dock="Left"
4: x:Name="wiImage"
5: Width="16"
6: Height="16"
7: Source="pack://application:,,/Resources/Images/WorkItems/unknown.gif">
8: </Image>
9: <Button x:Name="wiButton"
10: Content="{Binding Name}"
11: Style="{DynamicResource WelcomeButtonStyle}"
12: CommandParameter="{Binding}"
13: Command="Controlers:TeamSystemCommands.ChangeWorkItemTypeCommand">
14: </Button>
15: </DockPanel>
16: <DataTemplate.Triggers>
17: <DataTrigger Value="False">
18: <DataTrigger.Binding>
19: <Binding>
20: <Binding.Source>
21: <ObjectDataProvider ObjectType="{x:Type tfswitc:WorkItemType}"
22: MethodName="SupportedByHeat" />
23: </Binding.Source>
24: </Binding>
25: </DataTrigger.Binding>
26: <Setter TargetName="wiButton"
27: Property="IsEnabled"
28: Value="False" />
29: <Setter TargetName="wiButton"
30: Property="ToolTip"
31: Value="You will need to add the 'HeatITSM.Ref' field to use this work item." />
32: </DataTrigger>
33: </DataTemplate.Triggers>
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: Imports Microsoft.TeamFoundation.WorkItemTracking.Client
2:
3: Namespace TeamFoundationExtensions
4:
5:
6: Module WorkItemTypeExtensions
7:
8: <System.Runtime.CompilerServices.Extension()> _
9: Public Function SupportedByHeat(ByVal wit As WorkItemType) As Boolean
10: Dim c As Controlers.TeamSystemControler(Of MainWindow)
11: c = Application.ControlerFactory.GetControler(Of Controlers.TeamSystemControler(Of MainWindow))()
12: Return c.CheckWorkItemField(wit)
13: End Function
14:
15: End Module
16:
17: End Namespace
And this does not seam to work even if I import the namespace in the XAML:
1: <UserControl x:Class="SelectWorkItemType"
2: xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
3: xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
4: xmlns:d="http://schemas.microsoft.com/expression/blend/2006"
5: xmlns:tfs="clr-namespace:Microsoft.TeamFoundation.Client;assembly=Microsoft.TeamFoundation.Client"
6: xmlns:tfswitc="clr-namespace:Microsoft.TeamFoundation.WorkItemTracking.Client;assembly=Microsoft.TeamFoundation.WorkItemTracking.Client"
7: xmlns:tfse="clr-namespace:Hinshelwood.TFSHeatITSM.TeamFoundationExtensions"
8: xmlns:local="clr-namespace:Hinshelwood.TFSHeatITSM"
9: xmlns:Controlers="clr-namespace:Hinshelwood.TFSHeatITSM.Controlers"
10: xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
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 :)
Technorati Tags: .NET WPF WIT TFS
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