ArgumentNullException thrown from combobox in my custom activity - wpf

I have a simple custom activity demo of WF.
The XAML code:
<sap:ActivityDesigner x:Class="ActivityDesignerLibrary2.ActivityDesigner1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:sap="clr-namespace:System.Activities.Presentation;assembly=System.Activities.Presentation"
xmlns:sapv="clr-namespace:System.Activities.Presentation.View;assembly=System.Activities.Presentation">
<Grid>
<ComboBox x:Name="comboBox"
ItemsSource="{Binding Path=ModelItem.Values}"
SelectedValue="{Binding Path=ModelItem.Value, Mode=TwoWay}"
HorizontalAlignment="Left" Margin="36,0,0,0" VerticalAlignment="Top" Width="120"/>
</Grid>
</sap:ActivityDesigner>
The code behide:
[Designer(typeof(ActivityDesignerLibrary2.ActivityDesigner1))]
public class Class1 : CodeActivity
{
public List<string> Values { get; set; }
public string Value { get; set; }
public Class1()
{
Values = new List<string>() { "V1", "V2", "V3"};
Value = "V2";
}
protected override void Execute(CodeActivityContext context)
{
}
}
When I drag this custom activity into a workflow, an error messagebox is popped up.
I found it's SelectedValue make the error, but is there anything error and how to fix it?

Related

Control number of display buttons through binding

I wasn't sure the best way to word the title and couldn't find a related question, but if there is one then kindly direct me to it.
I'm trying to create a tender screen where the number of buttons displayed will be determined by how many types of tenders the user has setup (Cash, Check, Credit, Debit, Gift Card, etc).
So if I had a class like this:
public class TenderType
{
public string DisplayName { get; set; }
// ... other implementation details
}
And on my DataContext I have a TenderTypes collection declared like so:
public ObservableCollection<TenderType> TenderTypes { get; private set; }
Then how might I go about making my view udpate the number of buttons shown depending on how many TenderType instances are in the collection, and bind their Text properties to the DisplayName of the appropriate item in the collection?
You could use an ItemsControl and create a datatemplate for your TenderType to display a Button.
This way it will only show the buttons in your list
Xaml:
<Window x:Class="WpfApplication8.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication8"
Title="MainWindow" Height="105" Width="156" Name="UI">
<Window.Resources>
<DataTemplate DataType="{x:Type local:TenderType}">
<Button Content="{Binding DisplayName}" />
</DataTemplate>
</Window.Resources>
<Grid DataContext="{Binding ElementName=UI}">
<ItemsControl ItemsSource="{Binding TenderTypes}"/>
</Grid>
</Window>
Code:
public partial class MainWindow : Window
{
private ObservableCollection<TenderType> _sourceData = new ObservableCollection<TenderType>();
public MainWindow()
{
InitializeComponent();
TenderTypes.Add(new TenderType { DisplayName = "Stack" });
TenderTypes.Add(new TenderType { DisplayName = "Overflow" });
}
public ObservableCollection<TenderType> TenderTypes
{
get { return _sourceData; }
set { _sourceData = value; }
}
}
public class TenderType
{
public string DisplayName { get; set; }
}
Result:

Static Binding works compiled but not under designer

The following code works fine when compiled but I can't get the Text="{x:Static local:SomeClass+Limits.Name}" to work in the designer. Any help in this regard would be greatly appreciated! Thanks....
namespace StaticTest
{
public class SomeClass
{
public static class Limits
{
public const string Name = "It Works!";
}
}
}
<Window
x:Class="StaticTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:StaticTest"
Title="StaticTest"
Height="146"
Width="296"
WindowStartupLocation="CenterScreen">
<TextBlock
Grid.Column="1"
Grid.Row="1"
Text="{x:Static local:SomeClass+Limits.Name}" />
</Window>
I got it. As it turns out you need to do something like the following:
using System;
namespace StaticTest
{
public abstract class AbstractViewModel<VM, LC>
where VM : new()
where LC : new()
{
public AbstractViewModel()
{
Limits = new LC();
}
static AbstractViewModel()
{
Instance = new VM();
}
public LC Limits { get; private set; }
public static VM Instance { get; private set; }
}
public class MainWindowViewModel :
AbstractViewModel<MainWindowViewModel, MainWindowViewModel.LimitsClass>
{
public class LimitsClass
{
public LimitsClass()
{
Lots = new MinMax<int>(1, 10);
}
public MinMax<int> Lots { get; private set; }
}
}
}
<Window
x:Class="StaticTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:StaticTest"
Title="StaticTest"
Height="146"
Width="296"
WindowStartupLocation="CenterScreen">
<Grid>
<TextBlock
Text="{Binding Source={x:Static local:MainWindowViewModel.Instance}, Path=Limits.Lots.MaxValue}" />
</Grid>
</Window>
You need a binding as #H.B. says:
<TextBlock Text="{Binding Source={x:Static local:SomeClass+Limits.Name}}"/>
The VS2010 designer can't handle this, but it works fine in VS11 beta.

Binding data to ComboBox WPF

I am newbie to WPF, and needs help to bind data into the ComboBox. The xaml file contains the tag below.
<UserControl x:Class="SKAT.Postfordeler.Client.UI.View.ChooseInboxView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="42" d:DesignWidth="598">
<Grid>
<StackPanel Orientation="Horizontal">
<ComboBox Name="_currentInbox" Width="180" Margin="5" Height="22" DataContext="{Binding}" />
<Label Content="Et job kører allerede i denne indbakke (1500 ud af 1700 poster behandlet)" Name="_currentProcess" Margin="5" Height="25" />
</StackPanel>
</Grid>
//Inbox class , this class was implemented in seperate project
namespace SKAT.Postfordeler.Shared.DataTypes
{
[DataContract]
public class Inbox
{
[DataMember]
public String Id { get; set; }
[DataMember]
public String Folder { get; set; }
[DataMember]
public Rule Rules { get; set; }
}
}
//This code is located in the controller, the Activate method will fire when the MainWindow was executed
public void Activate()
{
var configuration = _configurationManager.GetConfiguration();// this method gets the xaml file settings
_chooseInboxView.FillInboxes(configuration.Inboxes); // Inboxes data binds to combobox
}
and in the View code behind, I created a method to bind the data which contains a type of list
public void FillInboxes(List<Inbox> inboxes)
{
DataContext = inboxes;
}
But it won't works,Any help please?
I assume your Inbox class consists of two properties (for simplicity), but there may be any number of them:
public class Inbox
{
public int ID { get; set; }
public string Text { get; set; }
}
You write a DataTemplate, for example:
<Grid.Resources>
<DataTemplate x:Key="InboxTemplate">
<WrapPanel>
<TextBlock Text="{Binding Path=ID}"/>
<TextBlock>:</TextBlock>
<TextBlock Text="{Binding Path=Text}"/>
</WrapPanel>
</DataTemplate>
</Grid.Resources>
Then correct your ComboBox declaration like:
<ComboBox Name="_currentInbox" Width="180" Margin="5" Height="22" ItemsSource="{Binding}" ItemTemplate="{StaticResource InboxTemplate}" />
Finally you set DataContext of your ComboBox to your List<Inbox>:
public void FillInboxes(List<Inbox> inboxes)
{
_currentInbox.DataContext = inboxes;
}
EDIT: As you've asked for a simpler solution, you can just override ToString() method of your Inbox class:
protected override string ToString()
{
return ID.ToString() + ":" + Text;
}
Instead of DataContext={Binding} you should have ItemsSource={Binding}.
The data context for any frameworkelement in the visual tree is by default {Binding}.
<ComboBox Name="_currentInbox"
SelectedItem="Hoved"
Width="180"
Margin="5"
Height="22"
DisplayMemberPath="Name"
ItemSource="{Binding}" />
Also for the combobox to display text of the items correctly I suppose you need DisplayMemberPath too. I assumed the property from Inbox class that you need to display is Name. Please replace with your relevant property name.
If your Inbox class is like,
public class Inbox
{
public int ID { get; set; }
public string Text { get; set; }
}
And if you do not want to change your xmal, the code behind method should be like this,
public void FillInboxes(List<Inbox> inboxes)
{
_currentInbox.DisplayMemberPath = "Text"; // To display the 'Text' property in the combobox dropdown
//_currentInbox.DisplayMemberPath = "ID"; // To display the 'ID' property in the combobox dropdown
_currentInbox.DataContext = inboxes;
}

How can I provide dynamic filtering on an entity collection?

I have a class ShipmentsCollection that inherits ObservableCollection which contains shipment objects (entities). This is displayed in a listbox on my ShipmentsView UserControl. My intent is to allow a user to type into a textbox above the list and filter the list with items that contain that string, as well as filter based on several checkbox and radiobutton based options (Delivery status and orderby direction).
I have tried this several ways, but none seem very elegant or really functional. Things I have tried follows:
Put ShipmentsCollection into a CollectionViewSource and filtered via predicate. Could not figure out a good way to make the filter auto update based on user typing or option change.
Refactored as a Class that Inherits collectionViewSource and tried to declare directly in XAML but got the following error: "The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid". Tried fixing but could not find solution that worked.
Refactored to inherit from CollectionView, implemented filter logic, in event handler in codebehind. Still trying to figure out how I can get the filter string to the event handler without naming the filtertext textbox control.
Anyone got some good ideas in regard to implementing this functionality in an MVVM design pattern. I expect to have at most 200 objects in the list, so it will not be an enormous filter operation.
Cory
Your first option would be the one I would suggest. To get the auto-filter to work based on typing, I'd do something like a SearchString property in my ViewModel, bind the textbox text to that, and set the UpdateSourceTrigger in the binding to PropertyChanged so it will call the SearchString PropertyChanged event every time a key is typed instead of waiting until the box loses focus.
XAML:
<TextBox Text="{Binding SearchString, UpdateSourceTrigger=PropertyChanged}" />
ViewModel: With the above property set to PropertyChanged, the "Set" method gets called anytime a key is typed instead of just when the textbox loses focus.
private string _searchString;
public string SearchString
{
get { return _searchString; }
set
{
if (_searchString != value)
{
_searchString = value;
OnPropertyChanged("SearchString");
}
}
}
I know this question is closed and old. but for someone like me searching for dynamic filtering, can refer to the following link
https://github.com/lokeshlal/WPFDynamicFilters
the above example creates filters for each entity based on the attribute defined on property of entity model.
As an example:
Define an attribute for filters
public class FilterAttribute : Attribute
{
public FilterAttribute() { }
public string FilterLabel { get; set; }
public object FilterValue { get; set; }
public string FilterKey { get; set; }
public Type FilterDataType { get; set; }
public bool IsDropDown { get; set; }
public string DropDownList { get; set; }
public List<object> ObjectDropDownList { get; set; }
}
Apply the above attribute in model properties
public class GridModel
{
[Filter(FilterLabel = "Id",
FilterKey = "Id",
IsDropDown = false,
FilterDataType = typeof(int))]
public int Id { get; set; }
[Filter(FilterLabel = "Name",
FilterKey = "Name",
IsDropDown = false,
FilterDataType = typeof(string))]
public string Name { get; set; }
[Filter(FilterLabel = "Country",
FilterKey = "Country",
IsDropDown = true,
FilterDataType = typeof(int),
DropDownList = "Country")]
public string Country { get; set; }
[Filter(FilterLabel = "Address",
FilterKey = "Address",
IsDropDown = false,
FilterDataType = typeof(string))]
public string Address { get; set; }
}
Define the model that will bind to the drop down type
public class Country
{
public int Id { get; set; } // id will be used for value
public string Name { get; set; } // Name will be used for display value
}
ViewModel of actual View
public class FilterViewModel
{
public ICommand CheckFiltersCommand { get; set; }
public FilterViewModel()
{
CheckFiltersCommand = new DelegateCommand(GetFilters);
GridSource = new List<GridModel>();
GridSource.Add(new GridModel() { Id = 1, Name = "Name1", Country = "Denmark" });
GridSource.Add(new GridModel() { Id = 2, Name = "Name2", Country = "India" });
GridSource.Add(new GridModel() { Id = 3, Name = "Name3", Country = "Australia" });
GridSource.Add(new GridModel() { Id = 4, Name = "Name4", Country = "India" });
GridSource.Add(new GridModel() { Id = 5, Name = "Name5", Country = "Australia" });
GridSource.Add(new GridModel() { Id = 6, Name = "Name6", Country = "Hongkong" });
FilterControlViewModel = new FilterControlViewModel();
FilterControlViewModel.FilterDetails = new List<FilterAttribute>();
foreach (var property in typeof(GridModel).GetProperties())
{
if (property.GetCustomAttributes(true).Where(attr => attr.GetType() == typeof(FilterAttribute)).Any())
{
var attribute = (FilterAttribute)property.GetCustomAttributes(true).Where(attr => attr.GetType() == typeof(FilterAttribute)).First();
FilterControlViewModel.FilterDetails.Add(attribute);
}
}
}
private void GetFilters()
{
FilterCollection = new Dictionary<string, object>();
foreach (var filter in FilterControlViewModel.FilterDetails)
{
if (filter.IsDropDown)
{
if (filter.FilterValue != null)
FilterCollection.Add(filter.FilterKey, filter.FilterValue.GetType().GetProperty("Id").GetValue(filter.FilterValue));
}
else
{
FilterCollection.Add(filter.FilterKey, filter.FilterValue);
}
}
MessageBox.Show(string.Join(", ", FilterCollection.Select(m => m.Key + ":" + Convert.ToString(m.Value)).ToArray()));
}
public List<GridModel> GridSource { get; set; }
public Dictionary<string, object> FilterCollection { get; set; }
public FilterControlViewModel FilterControlViewModel { get; set; }
}
In the above view model 'FilterControlViewModel' property will iterate all property of model and collect the filter information of the properties.
This same property will be assigned to the user control as explained in xaml file below
<Window x:Class="WPFDynamicFilters.GridWithFilters"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:WPFDynamicFilters"
mc:Ignorable="d"
Title="gridwithfilters" Height="481.239" Width="858.171">
<Grid>
<Grid HorizontalAlignment="Left" Margin="10,10,0,0" VerticalAlignment="Top" x:Name="FilterGrid" Height="209" Width="830">
<Border BorderThickness="1" BorderBrush="Gold"/>
<local:Filter DataContext="{Binding FilterControlViewModel, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Margin="0,0,0,10" />
</Grid>
<DataGrid x:Name="DataGrid" ItemsSource="{Binding GridSource}" HorizontalAlignment="Left" Margin="10,294,0,0" VerticalAlignment="Top" Height="146" Width="830"/>
<Button x:Name="button" Content="Check Filters" HorizontalAlignment="Left" Margin="10,245,0,0" VerticalAlignment="Top" Width="110" Command="{Binding CheckFiltersCommand}"/>
</Grid>
</Window>
Filter control will take all the attributes and render the control using itemscontrol
<UserControl x:Class="WPFDynamicFilters.Filter"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WPFDynamicFilters"
mc:Ignorable="d"
d:DesignHeight="40"
>
<UserControl.Resources>
<DataTemplate x:Key="TStringTemplate">
<StackPanel FlowDirection="LeftToRight">
<TextBlock Text="{Binding FilterKey}" />
<TextBox x:Name="TxtFieldValue"
Text="{Binding FilterValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
RenderTransformOrigin="-9.3,0.5" Width="200" FontSize="16" TextAlignment="Left" VerticalAlignment="Center"/>
</StackPanel>
</DataTemplate>
<DataTemplate x:Key="TIntegerTemplate">
<StackPanel FlowDirection="LeftToRight">
<TextBlock Text="{Binding FilterKey}" />
<TextBox x:Name="IntFieldValue"
Text="{Binding FilterValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
RenderTransformOrigin="-9.3,0.5" Width="200" FontSize="16" TextAlignment="Left" VerticalAlignment="Center"/>
</StackPanel>
</DataTemplate>
<DataTemplate x:Key="TDropDownTemplate">
<StackPanel FlowDirection="LeftToRight">
<TextBlock Text="{Binding FilterKey}" />
<ComboBox
SelectedItem="{Binding FilterValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
SelectedIndex="{Binding FilterValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
ItemsSource="{Binding ObjectDropDownList, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
DisplayMemberPath="Name"
RenderTransformOrigin="-9.3,0.5" Width="200" FontSize="16" />
</StackPanel>
</DataTemplate>
<local:FilterTemplateSelector x:Key="FilterTemplateSelector"
StringTemplate="{StaticResource TStringTemplate}"
IntegerTemplate="{StaticResource TIntegerTemplate}"
DropDownTemplate="{StaticResource TDropDownTemplate}"
/>
</UserControl.Resources>
<Grid>
<ItemsControl ItemsSource="{Binding FilterDetails}" >
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<UniformGrid Columns="3" />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<ContentControl
Content="{Binding}"
HorizontalAlignment="Left"
ContentTemplateSelector="{StaticResource FilterTemplateSelector}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</Grid>
</UserControl>
Finally define the template selector
public class FilterTemplateSelector : DataTemplateSelector
{
public DataTemplate StringTemplate { get; set; }
public DataTemplate IntegerTemplate { get; set; }
public DataTemplate DropDownTemplate { get; set; }
public override DataTemplate SelectTemplate(object item,
DependencyObject container)
{
var filter = (item as FilterAttribute);
if (filter == null) return StringTemplate;
if (!filter.IsDropDown)
{
switch (filter.FilterDataType.Name.ToLower())
{
case "int32":
case "int64":
return IntegerTemplate;
case "string":
return StringTemplate;
}
}
else
{
// display drop down
switch (filter.DropDownList)
{
case "Country":
filter.ObjectDropDownList = GetDropDown.GetCountries().ToList<object>();
break;
}
return DropDownTemplate;
}
return StringTemplate;
}
}

Silverlight Control Toolkit TreeView not rendering items

I'm trying to build a SL app with a TreeView in it. Here's my XAML:
<UserControl xmlns:controls="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls.Toolkit"
xmlns:tkwin="clr-namespace:System.Windows;assembly=System.Windows.Controls.Toolkit"
xmlns:basics="clr-namespace:System.Windows.Controls;assembly=System.Windows.Controls"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
x:Class="SL.MyApp.Page"
Width="800" Height="600">
<controls:DockPanel>
<controls:TreeView Name="siteTree" controls:DockPanel.Dock="Left" Width="150">
<controls:TreeView.ItemTemplate>
<tkwin:HierarchicalDataTemplate ItemsSource="{Binding Children}">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Name}"/>
</StackPanel>
</tkwin:HierarchicalDataTemplate>
</controls:TreeView.ItemTemplate>
</controls:TreeView>
<basics:TabControl controls:DockPanel.Dock="Right" TabStripPlacement="Top">
<basics:TabItem Header="Sites"></basics:TabItem>
<basics:TabItem Header="Lists"></basics:TabItem>
<basics:TabItem Header="Users"></basics:TabItem>
</basics:TabControl>
</controls:DockPanel>
</UserControl>
And the relevant codebehind:
namespace SL.MyApp
{
public partial class Page : UserControl
{
private ObservableCollection<WebDescriptor> _webHierarchy = new ObservableCollection<WebDescriptor>();
public Page(WebsSvc.WebsSoapClient websClient)
{
InitializeComponent();
siteTree.ItemsSource = _webHierarchy;
websClient.GetWebCollectionCompleted
+= new EventHandler<SL.SiteBuilder.WebsSvc.GetWebCollectionCompletedEventArgs>(websClient_GetWebCollectionCompleted);
websClient.GetWebCollectionAsync();
// TODO: some kind of spinner or progress bar needs to be started.
}
void websClient_GetWebCollectionCompleted(object sender, SL.SiteBuilder.WebsSvc.GetWebCollectionCompletedEventArgs e)
{
foreach (XElement xe in e.Result.Elements())
{
_webHierarchy.Add(ServiceObjectParser<WebDescriptor>.Parse(xe));
}
}
}
}
Update: The WebDescriptor class:
public class WebDescriptor
{
public string Title { get; set; }
public string Url { get; set; }
public List<WebDescriptor> Children { get; set; }
}
My problem is that nothing renders in the TreeView at all. I have verified that the results obtained in websClient_GetWebCollectionCompleted are valid and correct, but....nothing.
Any ideas?
in websClient_GetWebCollectionCompleted:
siteTree.ItemsSource = _webHierarchy;
Also, change your binding on the TextBlock in the Treeview to be {Binding Title}
After looking at the binding trace output, I finally realized I was trying to bind to a field instead of a property.
Doh!

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