Summary
Martin has been involved with computers in one way or another for as long as he can remember,
but started professionally in 2000. After university Martin started out as an ASP 3.0 developer
for a year working with Access and VBScript, but he breathed a sigh of relief when the .NET Framework
was released in 2001 and has been working with .NET and VB ever since. He has been certified in Team
Foundation Server since early 2007 and thinks it is the best thing since sliced bred. You can download
Martin Hinshelwood's CV to find out more.
.NET Evangelist, Architect, Application Developer. Particularly interested in Service Orientated
Architectures, client/server and relational database design using SQL Server, and .NET. Currently
working in the services industry, but with a background in community networking sites. Currently
specialising in MOSS 2007 and Sharepoint 3.0 as well as Team Foundation Server implementation,
deployment and development.
Specialties
- In-depth knowledge of .NET 3.5 (VB9,LINQ), .NET 3.0 (WCF), .NET 2.0
- Superb understanding of Service Orientated Architecture and Software Factories.
- Solid working knowledge of all Win32 platforms.
- Experience in client-server TCP messaging system.
- Excellent understanding of e-Mentoring and other relationship management systems.
- Solid knowlage of Microsoft Office Sharepoint Server 2007 and Windows Sharepoint Services 3.0
and Visual Studio 2005 Team Foundation Server
Calling an object method in a data trigger
Published on: Wednesday, August 27, 2008 [Permalink]
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 :)
