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  • What's the order of execution in property setters when using IDataErrorInfo?

    - by Benny Jobigan
    Situation: Many times with WPF, we use INotifyPropertyChanged and IDataErrorInfo to enable binding and validation on our data objects. I've got a lot of properties that look like this: public SomeObject SomeData { get { return _SomeData; } set { _SomeData = value; OnPropertyChanged("SomeData"); } } Of course, I have an appropriate overridden IDataErrorInfo.this[] in my class to do validation. Question: In a binding situation, when does the validation code get executed? When is the property set? When is the setter code executed? What if the validation fails? For example: User enters new data. Binding writes data to property. Property set method is executed. Binding checks this[] for validation. If the data is invalid, the binding sets the property back to the old value. Property set method is executed again. This is important if you are adding "hooks" into the set method, like: public string PathToFile { get { return _PathToFile; } set { if (_PathToFile != value && // prevent unnecessary actions OnPathToFileChanging(value)) // allow subclasses to do something or stop the setter { _PathToFile = value; OnPathToFileChanged(); // allow subclasses to do something afterwards OnPropertyChanged("PathToFile"); } } }

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  • How can I bind Wpf DataGridColumn to an object?

    - by John
    I want to bind the columns of my WPF DataGrid to some objects in a Dictionary like this: Binding Path=Objects[i] where Objects is my Dictionary of objects, so that each cell will represent an Object element. How can I do that? I suppose that I need to create a template for my cell, which I did, but how to get the result of column binding in my template? I know that by default the content of a DataGridCell is a TextBlock and it's Text property is set through column binding result, but if that result is an object I guess that I have to create a ContentTemplate. How do I do that, as the stuff I tried is not displaying anything. Here it is what I tried: <Style x:Key="CellStyle" TargetType="{x:Type dg:DataGridCell}"> <Setter Property="Template"> ---it should realy be ContentTemplate? <Setter.Value> <ControlTemplate> <controls:DataGridCellControl CurrentObject="{Binding }"/> -- I would expect to get the object like this for this column path : Path=Objects[i] but is not working </ControlTemplate> </Setter.Value> </Setter> </Style> So, to make myself completly clear, i want to get in CurrentObject property of my DataGridCellControl the current object that should result if I set the column binding in my data grid like this Path=Objects[i]. Thank you for any suggestion, John.

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  • I have a WPF/Silverlight ListView whose height is unpredictable and too high. How do I control it be

    - by Rob Perkins
    I have a ListView element with a DataTemplate for each ListViewItem defined as follows. When run, the ListView's height is not collapsed onto the items in the view, which is undesirable behavior: <DataTemplate x:Key="LicenseItemTemplate"> <Grid> <Grid.RowDefinitions> <RowDefinition Height="Auto" /> <RowDefinition Height="Auto" /> </Grid.RowDefinitions> <TextBlock Grid.Row="0" Text="{Binding company}"></TextBlock> <Grid Grid.Row="1" Style="{StaticResource HiddenWhenNotSelectedStyle}"> <Grid.RowDefinitions> <RowDefinition /> </Grid.RowDefinitions> <Button Grid.Row="0">ClickIt</Button> </Grid> </Grid> </DataTemplate> The second row of the outer grid has a style applied which looks like this. The purpose of the style is to : <Style TargetType="{x:Type Grid}" x:Key="HiddenWhenNotSelectedStyle" > <Style.Triggers> <DataTrigger Binding="{Binding Path=IsSelected, RelativeSource={ RelativeSource Mode=FindAncestor, AncestorType={x:Type ListViewItem} } }" Value="False"> <Setter Property="Grid.Visibility" Value="Collapsed" /> </DataTrigger> <DataTrigger Binding="{Binding Path=IsSelected, RelativeSource={ RelativeSource Mode=FindAncestor, AncestorType={x:Type ListViewItem} } }" Value="True"> <Setter Property="Grid.Visibility" Value="Visible" /> </DataTrigger> </Style.Triggers> </Style> The ListView renders like this: The desired appearance is this, when none of the elements are selected: ...with, of course, the ListView's height adjusting to accommodate the additional content when the second grid is made visible by selection. What can I do to get the desired behavior?

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  • Set focus to a button in a new TabItem

    - by Jan
    I use a TabControl to display a list of items. The ItemView is a separate control I wrote. <TabControl SelectedItem="{Binding CurrentItem}" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding ItemList}"> <TabControl.ContentTemplate> <DataTemplate> <ctrls:ItemView/> </DataTemplate> </TabControl.ContentTemplate> <TabControl.ItemTemplate> <DataTemplate> <TextBlock Text="{Binding ShortItemDescription}"/> </DataTemplate> </TabControl.ItemTemplate> </TabControl> If the user presses a Button a new ViewModel is added to the list of ViewModels and the TabControl displays it as a new tab. After adding the new tab is selected. <Button Command="{Binding AddItemCommand}" Content="Add item"/> Inside of the new ViewModel is a button that needs to be focused each time a new tab is added. I have tried to use the FocusManager and the Initialized event in the ItemView but these are only called for the first time I add a new tab. <UserControl x:Class="ItemView" ... Initialized="ViewInitialized"> <Grid> ... <!-- Set focus to this button --> <Button Content="Search" Command="{Binding SearchCommand}" Name="SearchButton" Grid.Column="0" Grid.Row="0"/> </Grid> </UserControl> Any ideas?

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  • WPF Edit hours and minutes of a DateTime

    - by PaN1C_Showt1Me
    Hi ! I have 3 TextBoxes to edit a DateTime. One to edit the Date and 2 to edit hour and minutes. How would you do that? The code below doesn't reflect the DateTime changes when editing the hour or minute: <TextBox Text="{Binding MyDateTime}" /> <TextBox Text="{Binding MyDateTime, StringFormat=\{0:HH\}}}" /> <TextBox Text="{Binding MyDateTime}, StringFormat=\{0:mm\}}" />

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  • Abstract mapping with custom JiBX marshaller

    - by aweigold
    I have created a custom JiBX marshaller and verified it works. It works by doing something like the following: <binding xmlns:tns="http://foobar.com/foo" direction="output"> <namespace uri="http://foobar.com/foo" default="elements"/> <mapping class="java.util.HashMap" marshaller="com.foobar.Marshaller1"/> <mapping name="context" class="com.foobar.Context"> <structure field="configuration"/> </mapping> </binding> However I need to create multiple marshallers for different HashMaps. So I tried to reference it with abstract mapping like this: <binding xmlns:tns="http://foobar.com/foo" direction="output"> <namespace uri="http://foobar.com/foo" default="elements"/> <mapping abstract="true" type-name="configuration" class="java.util.HashMap" marshaller="com.foobar.Marshaller1"/> <mapping abstract="true" type-name="overrides" class="java.util.HashMap" marshaller="com.foobar.Marshaller2"/> <mapping name="context" class="com.foobar.Context"> <structure map-as="configuration" field="configuration"/> <structure map-as="overrides" field="overrides"/> </mapping> </binding> However when doing so, when I attempt to build the binding, I receive the following: Error during code generation for file "E:\project\src\main\jibx\foo.jibx" - this may be due to an error in your binding or classpath, or to an error in the JiBX code My guess is that either I'm missing something I need to implement to enable my custom marshaller for abstract mapping, or custom marshallers do not support abstract mapping. I have found the IAbstractMarshaller interface in the JiBX API (http://jibx.sourceforge.net/api/org/jibx/runtime/IAbstractMarshaller.html), however the documentation seems unclear to me on if this is what I need to implement, as well as how it works if so. I have not been able to find an implementation of this interface to work off of as an example. My question is, how do you do abstract mapping with custom marshallers (if it's possible)? If it is done via the IAbstractMarshaller interface, how does it work and/or how should I implement it?

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  • custom control in DataGridTemplateColumn

    - by Johnsonlu
    Hi all, I'd like to add my custom control into a template column of data grid. The custom control is very similar to a text box, but has an icon in it. The user can click the icon, and selects an item from a prompted window, then the selected item will be filled into the text box. My problem is when the text box is filled, after I click the second column, the text will disappear. If I replace the custom control with a simple text box, the result is the same. Here is the sample code: //Employee.cs using System; using System.Collections.Generic; using System.Linq; using System.Text; namespace SimpleGridTest { public class Employee { public string Department { get; set; } public int ID { get; set; } public string Name { get; set; } } } Mainwindow.xaml <Window x:Class="SimpleGridTest.MainWindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="MainWindow" Height="350" Width="525"> <Grid> <DataGrid x:Name="grid" Grid.Row="1" Margin="5" AutoGenerateColumns="False" RowHeight="25" RowHeaderWidth="10" ItemsSource="{Binding}" CanUserAddRows="True" CanUserSortColumns="False"> <DataGrid.Columns> <DataGridTemplateColumn Header="Department" Width="150"> <DataGridTemplateColumn.CellTemplate> <DataTemplate> <TextBox Text="{Binding Department}" /> </DataTemplate> </DataGridTemplateColumn.CellTemplate> </DataGridTemplateColumn> <DataGridTextColumn Header="ID" Binding="{Binding Path=ID}" Width="100"/> <DataGridTextColumn Header="Name" Binding="{Binding Path=Name}" Width="200"/> </DataGrid.Columns> </DataGrid> </Grid> </Window> MainWindow.xaml.cs using System.Windows; using System.Collections.ObjectModel; namespace SimpleGridTest { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { private ObservableCollection<Employee> _employees = new ObservableCollection<Employee>(); public ObservableCollection<Employee> Employees { get { return _employees; } set { _employees = value; } } public MainWindow() { InitializeComponent(); grid.ItemsSource = Employees; } } } How can I fix this problem? Or I need to write a DataGrid***Column as DataGridTextColumn? Thanks in advance! Best Regards, Johnson

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  • WPF TextBox Focus

    - by Jezz
    I am setting focus on a Textbox like this: <DockPanel Margin="0,0,0,0" LastChildFill="True" FocusManager.FocusedElement="{Binding ElementName=messengerTextToSend}"> <ListBox x:Name="messengerLabelParticipants" DockPanel.Dock="Top" Height="79" Margin="0,1,0,0" Padding="0" Background="{x:Null}" BorderBrush="{x:Null}" BorderThickness="0" AllowDrop="True" ItemsSource="{Binding Path=involvedUsers}" ItemTemplate="{StaticResource chatParticipants}" Tag="{Binding Path=chatSessionID}" Drop="participantList_Drop" DragEnter="participantList_DragEnter" DragLeave="messengerLabelParticipants_DragLeave"> </ListBox> <TextBox x:Name="messengerTextToSend" Focusable="True" Margin="10,0,10,10" DockPanel.Dock="Bottom" Height="100" Tag="{Binding Path=.}" KeyUp="messengerTextToSend_KeyUp" Cursor="IBeam" Style="{StaticResource messengerTextBoxSendText}"/> <ScrollViewer x:Name="messengerScroller" Template="{DynamicResource ScrollViewerControlTemplate1}" ScrollChanged="messengerScroller_ScrollChanged" Loaded="messengerScroller_Loaded" Margin="0,10,0,10"> <ListBox x:Name="messengerListMessages" Margin="10,0,0,0" Padding="0" Background="{x:Null}" BorderBrush="{x:Null}" BorderThickness="0" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding Path=messages}" ItemTemplateSelector="{StaticResource messageTemplateSelector}"> </ListBox> </ScrollViewer> </DockPanel> However, when the page load, although the Textbox visually appears to have focus, the cursor is static and I have to manually either click on the Textbox or tab to it in order to start typing. I'm not sure what I'm doing wrong but I've tried every setting, inclduing setting it in the code to get it working. Any assistance would be greatly appreciated.

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  • Silverlight MVVM in VS2008 - a non starter?

    - by bplus
    I'm still very new to Silverlight. I'm currently using vs2008 at work. As far as I can gather Silverlight 4 is vs2010 only. I stumbled across this article on command binding, it says that command binding is a new feature introduced in silverlight 4. Is command binding integral to MVVM in silverlight, does it make MVVM much simpler to implement? Thanks for any help.

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  • Strange behaviour of CheckBox and TwoWay bound property

    - by walkor
    Hello, everyone. I fell in the following situation: I have a main UserControl with a DataGrid (which contains List). I need to show different panels depending on properties of the selected row(object). So i've created 2 controls and included them into this main control. Main control has 2 public properties - public List<ComplexObject> SourceList { get; set; } and public ComplexObject CurrentObject { get; set; } Pseudo-code: <UserControl x:Name="Main"> <DataGrid ItemsSource="{Binding SourceList}" SelectedItem="{Binding CurrentObject, Mode=TwoWay}"/> <Controls:RightPanelFirst Visibility="condition2"/> <Controls:RightPanelSecond Visibility="condition2"/> </UserControl> RightPanelFirst and RightPanelSecond have the following xaml: <UserControl> <... content here...> <CheckBox IsChecked="{Binding CurrentObject.ComplexProperty.SimpleProperty1, Mode=TwoWay}"> <CheckBox IsChecked="{Binding CurrentObject.ComplexProperty.SimpleProperty2, Mode=TwoWay}" x:Name="cbSecond"> <TextBox IsEnabled="{Binding IsChecked, ElementName=cbSecond}"/> </UserControl> So, my actual steps: Check both checkboxes (object values are set to true) Make other actions in code behind which modify CurrentObject. Then i want UI to reflect the changes, so I call NotifyPropertyChanged("CurrentObject"); SimpleProperty1 remains the same, but SimpleProperty2 resets to false I have no idea why this happens, can anyone help me please? Silverlight drives me mad.

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  • Displaying xaml resources dynamically?

    - by Robert
    I used Mike Swanson's illustrator to xaml converter to convert some of my images to xaml. The convert creates a viewbox that contains the image. These viewboxes I made resource files in my program. The code below shows what I'm trying to do: I have a viewmodel that has an enum variable called PrimaryWinding of type Windings. The values PrimD and PrimY of the enum select the respective PrimD and PrimY xaml files in the resources. <UserControl.Resources> <DataTemplate x:Key="PrimTrafo" DataType="{x:Type l:Windings}"> <Frame Source="{Binding}" x:Name="PART_Image" NavigationUIVisibility="Hidden"> <Frame.LayoutTransform> <ScaleTransform ScaleX="0.5" ScaleY="0.5"/> </Frame.LayoutTransform> </Frame> <DataTemplate.Triggers> <DataTrigger Binding="{Binding}" Value="PrimD"> <Setter TargetName="PART_Image" Property="Source" Value="Resources\PrimD.xaml" /> </DataTrigger> <DataTrigger Binding="{Binding}" Value="PrimY"> <Setter TargetName="PART_Image" Property="Source" Value="Resources\PrimY.xaml" /> </DataTrigger> </DataTemplate.Triggers> </DataTemplate> </UserControl.Resources> <!--The contentcontrol that holds the datatemplate defined above--> <Grid > <Grid.ColumnDefinitions> <ColumnDefinition Width="2*"></ColumnDefinition> <ColumnDefinition Width="2*"></ColumnDefinition> <ColumnDefinition Width="1*"></ColumnDefinition> </Grid.ColumnDefinitions> <ContentControl Grid.Column="0" Content="{Binding PrimaryWinding}" ContentTemplate="{StaticResource PrimTrafo}"/> </Grid> This code works. Only I can't resize the drawings to the size of the grid cell. I added the ScaleTransform class to resize the image. Is a Frame the wrong class to hold the drawings? Should I use the ScaleTransform class to resize the drawing to the size of the cell? And how can I do that dynamically?

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  • Access property of DataContext in ItemTemplate

    - by amrinder
    My datacontext has two properties: Items which is a collection and DetailsVisiblity which is enum of type Visiblity. On the page I have a Listbox with ItemsSource="{Binding Entries}". Inside the DataTemplate, I can bind stuff to properties of Items, but how do I get access to DetailsVisiblity which is a property of DataContext? DataContext has two properties: ObservableCollection<Item> Entries, and Visibility DetailsVisiblity. Item class has two properties: Title and Details. Here is the view. How do I bind Visiblity of the second TextBlock to DetailsVisiblity property? <ListBox "{Binding Items}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel> <TextBlock Text="{Binding Title}" /> <TextBlock Text="{Binding Details}" Visibility="{Binding ???}" /> </StackPanel> </DataTemplate> </ListBox.ItemTemplate> </ListBox>

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  • How to make a cell in a datagrid readonly based the content on another cell in SL4?

    - by Nair
    I have two columns, the second column depends on the content on the first column. By default, the second columns is readonly. When I enter some valid value, I want the second column to become editable. To achive this, I created a cell template and cell edit template on the second column where back ground and read only bound to the first column. On load, the first column is null so my second columns comes correctly as read only. Following is Cell Template for second column, where the background color is set by based on the first column. <DataTemplate> <Grid> <Border Background="{Binding FristColumn,Converter={StaticResource ColorConverter}}"/> <TextBlock Text="{Binding SecondColumn, Converter={StaticResource NumberFormatter}}" HorizontalAlignment="Stretch" VerticalAlignment="Center" Margin="0"/> </Grid> </DataTemplate> Following is cell edit template for second column to make it editable <DataTemplate> <Grid> <TextBox Text="{Binding SecondColumn, Mode=TwoWay, Converter={StaticResource NumberFormatter}}" Margin="0" HorizontalAlignment="Right" IsReadOnly="{Binding FirstColumn, Converter={StaticResource readOnlyConverter}, ConverterParameter=FirstColumn}" Background="{Binding Depend,Converter={StaticResource ColorConverter}, ConverterParameter=FirstColumn}" /> </Grid> </DataTemplate> With these two in place, when enter the valid value in the first column, I was expecting the second column color to change but it does not. But If I double click on the cell then it behaves properly based on the first cell. Is there some thing I am missing?

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  • WPF DataGrid populating blank rows on TreeView's SelectedItemChanged

    - by jes9582
    When my DataGrid populates on the TreeView's SelectedItemChanged event it finds the objects and creates the rows accordingly but the rows populate with no text or are just blank. So I know it is finding my objects but it is not displaying them properly. Does anyone see where I made an error or suggest any changes or fixes? Thank you in advance! Here is the CSharp code that is setting the DataGrid's ItemsSource (I am using .dbml and LINQ with Lambda expressions): dgSystemSettings.ItemsSource = (tvSystemConfiguration.SelectedItem as SYSTEM_SETTINGS_GROUP).SYSTEM_SETTINGS_NAMEs.Join(ssdc.SYSTEM_SETTINGS_VALUEs, x => x.SSN_ID, y => y.SSV_SSN_ID, (x, y) => new { SYSTEM_SETTINGS_NAME = x, SYSTEM_SETTINGS_VALUE = y }); And here is the .xaml: <DataGrid Name="dgSystemSettings" AutoGenerateColumns="False" Height="447" Width="513" DockPanel.Dock="Right" ItemsSource="{Binding}" VerticalAlignment="Top" Margin="10,10,0,0"> <DataGrid.Columns> <DataGridTextColumn x:Name="colDisplayName" Header="Name" Binding="{Binding SSN_DISPLAY_NAME}"></DataGridTextColumn> <DataGridTextColumn x:Name="colValue" Header="Value" Binding="{Binding SSV_VALUE}"></DataGridTextColumn> </DataGrid.Columns> </DataGrid>

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  • Can I enable PreviewClick using InputBindings in WPF?

    - by No hay Problema
    I want to detect when a user clicks on an item on a listview, without using events as I do command binding and I don't like all the nonsense of the behaviours. I have tried this: <ListView x:Name="MainList" Margin="2,8,6,8" Background="Black" ItemsSource="{Binding Path=AssetsVM.Data, Mode=OneWay}" BorderBrush="{x:Null}" > <ListView.InputBindings> <MouseBinding Command="{Binding Path=AssetsVM.SelectActivo}" CommandParameter="{Binding ElementName=MainList, Path=SelectedItem}" MouseAction="LeftClick" /> </ListView.InputBindings> This works fine if I click on the listview but does not work on the items, what I need is either a way to enable "Preview" or have a MouseAction/Gesture that behaves as preview, is it possible? Thanks

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  • Limiting the width of a TextBlock in Silverlight

    - by Druzil
    The obvious MaxWidth gets ignored and the text in the "DisplayBox" TextBlock displays the whole text even if this text continues past the parent container controls (to the edge of the silverlight area. <win:HierarchicalDataTemplate x:Key="hierarchicalTemplate" ItemsSource="{Binding _children}"> <Border BorderThickness="0" BorderBrush="Orange" HorizontalAlignment="Stretch" Background="{Binding Converter={StaticResource BackgroundConverter}}"> <toolkit:DockPanel LastChildFill="True" Width="{Binding HeirarchyLevel, Converter={StaticResource WidthConverter}}" Height="20"> <Canvas toolkit:DockPanel.Dock="Right" Width="20" MouseLeftButtonUp="Arrow_MouseLeftButtonDown"> <Rectangle Width="20" Height="20" Fill="Transparent" /> <Line Stroke="Black" X1="5" Y1="10" X2="17" Y2="10" /> <Line Stroke="Black" X1="11" Y1="5" X2="17" Y2="10" /> <Line Stroke="Black" X1="11" Y1="15" X2="17" Y2="10" /> </Canvas> <Ellipse Canvas.Top="5" Width="10" Height="10" Fill="Green" toolkit:DockPanel.Dock="Right" MouseLeftButtonDown="Ellipse_MouseLeftButtonDown" /> <Canvas Width="Auto" Loaded="TextArea_Loaded"> <TextBlock Name="DisplayBox" FontFamily="Arial" FontSize="17" Foreground="Black" Width="Auto" Text="{Binding TaskName}" MouseLeftButtonUp="TextBlock_MouseLeftButtonUp" /> <TextBox Name="EditBox" FontFamily="Arial" FontSize="10" Foreground="Black" Height="20" Text="{Binding TaskName}" Visibility="Collapsed" LostFocus="TextBox_LostFocus" /> <Line Stroke="Black" X1="0" Y1="10" X2="202" Y2="10" Width="Auto" /> </Canvas> </toolkit:DockPanel> </Border> </win:HierarchicalDataTemplate>

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  • Populate two column grid with databinding?

    - by Richard
    How do i populate a two column grid with objects from my observable collection? I've tried to achieve this effect by using the tookits wrap panel but the items just stack. <toolkit:WrapPanel Margin="5,0,0,0" Width="400"> <ItemsControl ItemsSource="{Binding Trips}"> <ItemsControl.ItemTemplate> <DataTemplate> <StackPanel Height="236" Width="182"> <Button Style="{StaticResource VasttrafikButtonTrip}"> <StackPanel Width="152" Height="140"> <TextBlock Text="{Binding FromName}" /> <TextBlock FontFamily="Segoe WP Semibold" Text="till" /> <TextBlock Text="{Binding ToName}" /> </StackPanel> </Button> <TextBlock HorizontalAlignment="Left" Width="160" FontSize="16" FontWeight="ExtraBlack" Text="{Binding TravelTimeText}" /> <TextBlock HorizontalAlignment="Left" Width="160" Margin="0,-6,0,0" FontSize="16" Text="{Binding TransferCountText}" /> </StackPanel> </DataTemplate> </ItemsControl.ItemTemplate> </ItemsControl> </toolkit:WrapPanel>

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  • Expanders inside listbox leaving blank space on collapse

    - by siz
    We have a rather complex UI that is presenting some problems for us. I have a ListBox that contains a set of DataItems. The DataTemplate for each item is an Expander. The header is text, the content of the Expander is a ListBox. The ListBox contains SubDataItems. The DataTemplate for each SubDataItem is an Expander. Here is a simplified XAML in which I reproduce the issue: <ListBox ItemsSource="{Binding Items}"> <ListBox.ItemTemplate> <DataTemplate> <Expander Header="{Binding Header}"> <ListBox ItemsSource="{Binding SubItems}"> <ListBox.ItemTemplate> <DataTemplate> <Expander Header="{Binding SubHeader}"> <Grid Height="40"> <TextBlock Text="{Binding SubText}" /> </Grid> </Expander> </DataTemplate> </ListBox.ItemTemplate> </ListBox> </Expander> </DataTemplate> </ListBox.ItemTemplate> </ListBox> There is a problem with how the layout is produced. If any Expander corresponding to the SubDataItem is expanded, the ListBoxItem containing this ListBox (the Expander.Content in the parent DataTemplate) correctly requests more space. So I can expand all SubDataItems and correctly see my data. However, when I collapse, the space I previously asked to expand, remains blank, instead of being reclaimed by the ListBoxItem. This is a problem because if I have say 10 SubDataItems and happen to expand all of them at the same time and then collapse, there is a significant amount of white space wasting my real estate. How can I force WPF to resize the ListBoxItem to the correct state?

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  • How do I change text color on the selected row inside a ListView/GridView? (using Expression Dark th

    - by Thiado de Arruda
    I'm using theExpression Dark WPF Theme(http://wpfthemes.codeplex.com/) with a ListView(view property set to a GridView) to display some user data like the following : <ListView Grid.Row="1" ItemsSource="{Binding RegisteredUsers}" SelectedItem="{Binding SelectedUser}" > <ListView.View> <GridView> <GridViewColumn Header="Login" DisplayMemberBinding="{Binding Login}" Width="60"/> <GridViewColumn Header="Full Name" DisplayMemberBinding="{Binding FullName}" Width="180"/> <GridViewColumn Header="Last logon" DisplayMemberBinding="{Binding LastLogon}" Width="120"/> <GridViewColumn Header="Photo" Width="50"> <GridViewColumn.CellTemplate> <DataTemplate> <Image Source="{Binding Photo}" Width="30" Height="35"/> </DataTemplate> </GridViewColumn.CellTemplate> </GridViewColumn> </GridView> </ListView.View> </ListView> The rows have white text with a dark background and white background when selected, however the text color doesnt change when selected and it makes very difficult to read, I would like the text to have a dark color when the row is selected. I have searched for a way to style the text color but with no success, here is the control template for the ListViewItem : <Border SnapsToDevicePixels="true" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" CornerRadius="2" x:Name="border"> <Grid Margin="2,0,2,0"> <Rectangle x:Name="Background" IsHitTestVisible="False" Opacity="0.25" Fill="{StaticResource NormalBrush}" RadiusX="1" RadiusY="1"/> <Rectangle x:Name="HoverRectangle" IsHitTestVisible="False" Opacity="0" Fill="{StaticResource NormalBrush}" RadiusX="1" RadiusY="1"/> <Rectangle x:Name="SelectedRectangle" IsHitTestVisible="False" Opacity="0" Fill="{StaticResource SelectedBackgroundBrush}" RadiusX="1" RadiusY="1"/> <GridViewRowPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" Margin="0,2,0,2" VerticalAlignment="Stretch" /> </Grid> </Border> The trigger that changes the background color simply applies an animation to change the 'SelectedRectangle' opacity, but I cant change the text color on the same trigger(I tried using a setter for the foreground color on the ListViewItem, but with no success). Does someone have a clue on that?

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  • Metro: Creating a Master/Detail View with a WinJS ListView Control

    - by Stephen.Walther
    The goal of this blog entry is to explain how you can create a simple master/detail view by using the WinJS ListView and Template controls. In particular, I explain how you can use a ListView control to display a list of movies and how you can use a Template control to display the details of the selected movie. Creating a master/detail view requires completing the following four steps: Create the data source – The data source contains the list of movies. Declare the ListView control – The ListView control displays the entire list of movies. It is the master part of the master/detail view. Declare the Details Template control – The Details Template control displays the details for the selected movie. It is the details part of the master/detail view. Handle the selectionchanged event – You handle the selectionchanged event to display the details for a movie when a new movie is selected. Creating the Data Source There is nothing special about our data source. We initialize a WinJS.Binding.List object to represent a list of movies: (function () { "use strict"; var movies = new WinJS.Binding.List([ { title: "Star Wars", director: "Lucas"}, { title: "Shrek", director: "Adamson" }, { title: "Star Trek", director: "Abrams" }, { title: "Spiderman", director: "Raimi" }, { title: "Memento", director: "Nolan" }, { title: "Minority Report", director: "Spielberg" } ]); // Expose the data source WinJS.Namespace.define("ListViewDemos", { movies: movies }); })(); The data source is exposed to the rest of our application with the name ListViewDemos.movies. Declaring the ListView Control The ListView control is declared with the following markup: <div id="movieList" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: ListViewDemos.movies.dataSource, itemTemplate: select('#masterItemTemplate'), tapBehavior: 'directSelect', selectionMode: 'single', layout: { type: WinJS.UI.ListLayout } }"> </div> The data-win-options attribute is used to set the following properties of the ListView control: itemDataSource – The ListView is bound to the list of movies which we created in the previous section. Notice that the ListView is bound to ListViewDemos.movies.dataSource and not just ListViewDemos.movies. itemTemplate – The item template contains the template used for rendering each item in the ListView. The markup for this template is included below. tabBehavior – This enumeration determines what happens when you tap or click on an item in the ListView. The possible values are directSelect, toggleSelect, invokeOnly, none. Because we want to handle the selectionchanged event, we set tapBehavior to the value directSelect. selectionMode – This enumeration determines whether you can select multiple items or only a single item. The possible values are none, single, multi. In the code above, this property is set to the value single. layout – You can use ListLayout or GridLayout with a ListView. If you want to display a vertical ListView, then you should select ListLayout. You must associate a ListView with an item template if you want to render anything interesting. The ListView above is associated with an item template named #masterItemTemplate. Here’s the markup for the masterItemTemplate: <div id="masterItemTemplate" data-win-control="WinJS.Binding.Template"> <div class="movie"> <span data-win-bind="innerText:title"></span> </div> </div> This template simply renders the title of each movie. Declaring the Details Template Control The details part of the master/detail view is created with the help of a Template control. Here’s the markup used to declare the Details Template control: <div id="detailsTemplate" data-win-control="WinJS.Binding.Template"> <div> <div> Title: <span data-win-bind="innerText:title"></span> </div> <div> Director: <span data-win-bind="innerText:director"></span> </div> </div> </div> The Details Template control displays the movie title and director.   Handling the selectionchanged Event The ListView control can raise two types of events: the iteminvoked and selectionchanged events. The iteminvoked event is raised when you click on a ListView item. The selectionchanged event is raised when one or more ListView items are selected. When you set the tapBehavior property of the ListView control to the value “directSelect” then tapping or clicking a list item raised both the iteminvoked and selectionchanged event. Tapping a list item causes the item to be selected and the item appears with a checkmark. In our code, we handle the selectionchanged event to update the movie details Template when you select a new movie. Here’s the code from the default.js file used to handle the selectionchanged event: var movieList = document.getElementById("movieList"); var detailsTemplate = document.getElementById("detailsTemplate"); var movieDetails = document.getElementById("movieDetails"); // Setup selectionchanged handler movieList.winControl.addEventListener("selectionchanged", function (evt) { if (movieList.winControl.selection.count() > 0) { movieList.winControl.selection.getItems().then(function (items) { // Clear the template container movieDetails.innerHTML = ""; // Render the template detailsTemplate.winControl.render(items[0].data, movieDetails); }); } }); The code above sets up an event handler (listener) for the selectionchanged event. The event handler first verifies that an item has been selected in the ListView (selection.count() > 0). Next, the details for the movie are rendered using the movie details Template (we created this Template in the previous section). The Complete Code For the sake of completeness, I’ve included the complete code for the master/detail view below. I’ve included both the default.html, default.js, and movies.js files. Here is the final code for the default.html file: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>ListViewMasterDetail</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- ListViewMasterDetail references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> <script type="text/javascript" src="js/movies.js"></script> <style type="text/css"> body { font-size: xx-large; } .movie { padding: 5px; } #masterDetail { display: -ms-box; } #movieList { width: 300px; margin: 20px; } #movieDetails { margin: 20px; } </style> </head> <body> <!-- Templates --> <div id="masterItemTemplate" data-win-control="WinJS.Binding.Template"> <div class="movie"> <span data-win-bind="innerText:title"></span> </div> </div> <div id="detailsTemplate" data-win-control="WinJS.Binding.Template"> <div> <div> Title: <span data-win-bind="innerText:title"></span> </div> <div> Director: <span data-win-bind="innerText:director"></span> </div> </div> </div> <!-- Master/Detail --> <div id="masterDetail"> <!-- Master --> <div id="movieList" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: ListViewDemos.movies.dataSource, itemTemplate: select('#masterItemTemplate'), tapBehavior: 'directSelect', selectionMode: 'single', layout: { type: WinJS.UI.ListLayout } }"> </div> <!-- Detail --> <div id="movieDetails"></div> </div> </body> </html> Here is the default.js file: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.UI.processAll(); var movieList = document.getElementById("movieList"); var detailsTemplate = document.getElementById("detailsTemplate"); var movieDetails = document.getElementById("movieDetails"); // Setup selectionchanged handler movieList.winControl.addEventListener("selectionchanged", function (evt) { if (movieList.winControl.selection.count() > 0) { movieList.winControl.selection.getItems().then(function (items) { // Clear the template container movieDetails.innerHTML = ""; // Render the template detailsTemplate.winControl.render(items[0].data, movieDetails); }); } }); } }; app.start(); })();   Here is the movies.js file: (function () { "use strict"; var movies = new WinJS.Binding.List([ { title: "Star Wars", director: "Lucas"}, { title: "Shrek", director: "Adamson" }, { title: "Star Trek", director: "Abrams" }, { title: "Spiderman", director: "Raimi" }, { title: "Memento", director: "Nolan" }, { title: "Minority Report", director: "Spielberg" } ]); // Expose the data source WinJS.Namespace.define("ListViewDemos", { movies: movies }); })();   Summary The purpose of this blog entry was to describe how to create a simple master/detail view by taking advantage of the WinJS ListView control. We handled the selectionchanged event of the ListView control to display movie details when you select a movie in the ListView.

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  • Metro: Understanding Observables

    - by Stephen.Walther
    The goal of this blog entry is to describe how the Observer Pattern is implemented in the WinJS library. You learn how to create observable objects which trigger notifications automatically when their properties are changed. Observables enable you to keep your user interface and your application data in sync. For example, by taking advantage of observables, you can update your user interface automatically whenever the properties of a product change. Observables are the foundation of declarative binding in the WinJS library. The WinJS library is not the first JavaScript library to include support for observables. For example, both the KnockoutJS library and the Microsoft Ajax Library (now part of the Ajax Control Toolkit) support observables. Creating an Observable Imagine that I have created a product object like this: var product = { name: "Milk", description: "Something to drink", price: 12.33 }; Nothing very exciting about this product. It has three properties named name, description, and price. Now, imagine that I want to be notified automatically whenever any of these properties are changed. In that case, I can create an observable product from my product object like this: var observableProduct = WinJS.Binding.as(product); This line of code creates a new JavaScript object named observableProduct from the existing JavaScript object named product. This new object also has a name, description, and price property. However, unlike the properties of the original product object, the properties of the observable product object trigger notifications when the properties are changed. Each of the properties of the new observable product object has been changed into accessor properties which have both a getter and a setter. For example, the observable product price property looks something like this: price: { get: function () { return this.getProperty(“price”); } set: function (value) { this.setProperty(“price”, value); } } When you read the price property then the getProperty() method is called and when you set the price property then the setProperty() method is called. The getProperty() and setProperty() methods are methods of the observable product object. The observable product object supports the following methods and properties: · addProperty(name, value) – Adds a new property to an observable and notifies any listeners. · backingData – An object which represents the value of each property. · bind(name, action) – Enables you to execute a function when a property changes. · getProperty(name) – Returns the value of a property using the string name of the property. · notify(name, newValue, oldValue) – A private method which executes each function in the _listeners array. · removeProperty(name) – Removes a property and notifies any listeners. · setProperty(name, value) – Updates a property and notifies any listeners. · unbind(name, action) – Enables you to stop executing a function in response to a property change. · updateProperty(name, value) – Updates a property and notifies any listeners. So when you create an observable, you get a new object with the same properties as an existing object. However, when you modify the properties of an observable object, then you can notify any listeners of the observable that the value of a particular property has changed automatically. Imagine that you change the value of the price property like this: observableProduct.price = 2.99; In that case, the following sequence of events is triggered: 1. The price setter calls the setProperty(“price”, 2.99) method 2. The setProperty() method updates the value of the backingData.price property and calls the notify() method 3. The notify() method executes each function in the collection of listeners associated with the price property Creating Observable Listeners If you want to be notified when a property of an observable object is changed, then you need to register a listener. You register a listener by using the bind() method like this: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price observableProduct.price = 2.99; } }; app.start(); })(); In the code above, the bind() method is used to associate the price property with a function. When the price property is changed, the function logs the new value of the price property to the Visual Studio JavaScript console. The price property is associated with the function using the following line of code: // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); Coalescing Notifications If you make multiple changes to a property – one change immediately following another – then separate notifications won’t be sent. Instead, any listeners are notified only once. The notifications are coalesced into a single notification. For example, in the following code, the product price property is updated three times. However, only one message is written to the JavaScript console. Only the last value assigned to the price property is written to the JavaScript Console window: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price observableProduct.price = 3.99; observableProduct.price = 2.99; observableProduct.price = 1.99; Only the last value assigned to price, the value 1.99, appears in the console: If there is a time delay between changes to a property then changes result in different notifications. For example, the following code updates the price property every second: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Add 1 to price every second window.setInterval(function () { observableProduct.price += 1; }, 1000); In this case, separate notification messages are logged to the JavaScript Console window: If you need to prevent multiple notifications from being coalesced into one then you can take advantage of promises. I discussed WinJS promises in a previous blog entry: http://stephenwalther.com/blog/archive/2012/02/22/windows-web-applications-promises.aspx Because the updateProperty() method returns a promise, you can create different notifications for each change in a property by using the following code: // Change the price observableProduct.updateProperty("price", 3.99) .then(function () { observableProduct.updateProperty("price", 2.99) .then(function () { observableProduct.updateProperty("price", 1.99); }); }); In this case, even though the price is immediately changed from 3.99 to 2.99 to 1.99, separate notifications for each new value of the price property are sent. Bypassing Notifications Normally, if a property of an observable object has listeners and you change the property then the listeners are notified. However, there are certain situations in which you might want to bypass notification. In other words, you might need to change a property value silently without triggering any functions registered for notification. If you want to change a property without triggering notifications then you should change the property by using the backingData property. The following code illustrates how you can change the price property silently: // Simple product object var product = { name: "Milk", description: "Something to drink", price: 12.33 }; // Create observable product var observableProduct = WinJS.Binding.as(product); // Execute a function when price is changed observableProduct.bind("price", function (newValue) { console.log(newValue); }); // Change the price silently observableProduct.backingData.price = 5.99; console.log(observableProduct.price); // Writes 5.99 The price is changed to the value 5.99 by changing the value of backingData.price. Because the observableProduct.price property is not set directly, any listeners associated with the price property are not notified. When you change the value of a property by using the backingData property, the change in the property happens synchronously. However, when you change the value of an observable property directly, the change is always made asynchronously. Summary The goal of this blog entry was to describe observables. In particular, we discussed how to create observables from existing JavaScript objects and bind functions to observable properties. You also learned how notifications are coalesced (and ways to prevent this coalescing). Finally, we discussed how you can use the backingData property to update an observable property without triggering notifications. In the next blog entry, we’ll see how observables are used with declarative binding to display the values of properties in an HTML document.

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  • Metro: Creating a Master/Detail View with a WinJS ListView Control

    - by Stephen.Walther
    The goal of this blog entry is to explain how you can create a simple master/detail view by using the WinJS ListView and Template controls. In particular, I explain how you can use a ListView control to display a list of movies and how you can use a Template control to display the details of the selected movie. Creating a master/detail view requires completing the following four steps: Create the data source – The data source contains the list of movies. Declare the ListView control – The ListView control displays the entire list of movies. It is the master part of the master/detail view. Declare the Details Template control – The Details Template control displays the details for the selected movie. It is the details part of the master/detail view. Handle the selectionchanged event – You handle the selectionchanged event to display the details for a movie when a new movie is selected. Creating the Data Source There is nothing special about our data source. We initialize a WinJS.Binding.List object to represent a list of movies: (function () { "use strict"; var movies = new WinJS.Binding.List([ { title: "Star Wars", director: "Lucas"}, { title: "Shrek", director: "Adamson" }, { title: "Star Trek", director: "Abrams" }, { title: "Spiderman", director: "Raimi" }, { title: "Memento", director: "Nolan" }, { title: "Minority Report", director: "Spielberg" } ]); // Expose the data source WinJS.Namespace.define("ListViewDemos", { movies: movies }); })(); The data source is exposed to the rest of our application with the name ListViewDemos.movies. Declaring the ListView Control The ListView control is declared with the following markup: <div id="movieList" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: ListViewDemos.movies.dataSource, itemTemplate: select('#masterItemTemplate'), tapBehavior: 'directSelect', selectionMode: 'single', layout: { type: WinJS.UI.ListLayout } }"> </div> The data-win-options attribute is used to set the following properties of the ListView control: itemDataSource – The ListView is bound to the list of movies which we created in the previous section. Notice that the ListView is bound to ListViewDemos.movies.dataSource and not just ListViewDemos.movies. itemTemplate – The item template contains the template used for rendering each item in the ListView. The markup for this template is included below. tabBehavior – This enumeration determines what happens when you tap or click on an item in the ListView. The possible values are directSelect, toggleSelect, invokeOnly, none. Because we want to handle the selectionchanged event, we set tapBehavior to the value directSelect. selectionMode – This enumeration determines whether you can select multiple items or only a single item. The possible values are none, single, multi. In the code above, this property is set to the value single. layout – You can use ListLayout or GridLayout with a ListView. If you want to display a vertical ListView, then you should select ListLayout. You must associate a ListView with an item template if you want to render anything interesting. The ListView above is associated with an item template named #masterItemTemplate. Here’s the markup for the masterItemTemplate: <div id="masterItemTemplate" data-win-control="WinJS.Binding.Template"> <div class="movie"> <span data-win-bind="innerText:title"></span> </div> </div> This template simply renders the title of each movie. Declaring the Details Template Control The details part of the master/detail view is created with the help of a Template control. Here’s the markup used to declare the Details Template control: <div id="detailsTemplate" data-win-control="WinJS.Binding.Template"> <div> <div> Title: <span data-win-bind="innerText:title"></span> </div> <div> Director: <span data-win-bind="innerText:director"></span> </div> </div> </div> The Details Template control displays the movie title and director.   Handling the selectionchanged Event The ListView control can raise two types of events: the iteminvoked and selectionchanged events. The iteminvoked event is raised when you click on a ListView item. The selectionchanged event is raised when one or more ListView items are selected. When you set the tapBehavior property of the ListView control to the value “directSelect” then tapping or clicking a list item raised both the iteminvoked and selectionchanged event. Tapping a list item causes the item to be selected and the item appears with a checkmark. In our code, we handle the selectionchanged event to update the movie details Template when you select a new movie. Here’s the code from the default.js file used to handle the selectionchanged event: var movieList = document.getElementById("movieList"); var detailsTemplate = document.getElementById("detailsTemplate"); var movieDetails = document.getElementById("movieDetails"); // Setup selectionchanged handler movieList.winControl.addEventListener("selectionchanged", function (evt) { if (movieList.winControl.selection.count() > 0) { movieList.winControl.selection.getItems().then(function (items) { // Clear the template container movieDetails.innerHTML = ""; // Render the template detailsTemplate.winControl.render(items[0].data, movieDetails); }); } }); The code above sets up an event handler (listener) for the selectionchanged event. The event handler first verifies that an item has been selected in the ListView (selection.count() > 0). Next, the details for the movie are rendered using the movie details Template (we created this Template in the previous section). The Complete Code For the sake of completeness, I’ve included the complete code for the master/detail view below. I’ve included both the default.html, default.js, and movies.js files. Here is the final code for the default.html file: <!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>ListViewMasterDetail</title> <!-- WinJS references --> <link href="//Microsoft.WinJS.0.6/css/ui-dark.css" rel="stylesheet"> <script src="//Microsoft.WinJS.0.6/js/base.js"></script> <script src="//Microsoft.WinJS.0.6/js/ui.js"></script> <!-- ListViewMasterDetail references --> <link href="/css/default.css" rel="stylesheet"> <script src="/js/default.js"></script> <script type="text/javascript" src="js/movies.js"></script> <style type="text/css"> body { font-size: xx-large; } .movie { padding: 5px; } #masterDetail { display: -ms-box; } #movieList { width: 300px; margin: 20px; } #movieDetails { margin: 20px; } </style> </head> <body> <!-- Templates --> <div id="masterItemTemplate" data-win-control="WinJS.Binding.Template"> <div class="movie"> <span data-win-bind="innerText:title"></span> </div> </div> <div id="detailsTemplate" data-win-control="WinJS.Binding.Template"> <div> <div> Title: <span data-win-bind="innerText:title"></span> </div> <div> Director: <span data-win-bind="innerText:director"></span> </div> </div> </div> <!-- Master/Detail --> <div id="masterDetail"> <!-- Master --> <div id="movieList" data-win-control="WinJS.UI.ListView" data-win-options="{ itemDataSource: ListViewDemos.movies.dataSource, itemTemplate: select('#masterItemTemplate'), tapBehavior: 'directSelect', selectionMode: 'single', layout: { type: WinJS.UI.ListLayout } }"> </div> <!-- Detail --> <div id="movieDetails"></div> </div> </body> </html> Here is the default.js file: (function () { "use strict"; var app = WinJS.Application; app.onactivated = function (eventObject) { if (eventObject.detail.kind === Windows.ApplicationModel.Activation.ActivationKind.launch) { WinJS.UI.processAll(); var movieList = document.getElementById("movieList"); var detailsTemplate = document.getElementById("detailsTemplate"); var movieDetails = document.getElementById("movieDetails"); // Setup selectionchanged handler movieList.winControl.addEventListener("selectionchanged", function (evt) { if (movieList.winControl.selection.count() > 0) { movieList.winControl.selection.getItems().then(function (items) { // Clear the template container movieDetails.innerHTML = ""; // Render the template detailsTemplate.winControl.render(items[0].data, movieDetails); }); } }); } }; app.start(); })();   Here is the movies.js file: (function () { "use strict"; var movies = new WinJS.Binding.List([ { title: "Star Wars", director: "Lucas"}, { title: "Shrek", director: "Adamson" }, { title: "Star Trek", director: "Abrams" }, { title: "Spiderman", director: "Raimi" }, { title: "Memento", director: "Nolan" }, { title: "Minority Report", director: "Spielberg" } ]); // Expose the data source WinJS.Namespace.define("ListViewDemos", { movies: movies }); })();   Summary The purpose of this blog entry was to describe how to create a simple master/detail view by taking advantage of the WinJS ListView control. We handled the selectionchanged event of the ListView control to display movie details when you select a movie in the ListView.

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  • Stumbling Through: Visual Studio 2010 (Part IV)

    So finally we get to the fun part the fruits of all of our middle-tier/back end labors of generating classes to interface with an XML data source that the previous posts were about can now be presented quickly and easily to an end user.  I think.  Well see.  Well be using a WPF window to display all of our various MFL information that weve collected in the two XML files, and well provide a means of adding, updating and deleting each of these entities using as little code as possible.  Additionally, I would like to dig into the performance of this solution as well as the flexibility of it if were were to modify the underlying XML schema.  So first things first, lets create a WPF project and include our xml data in a data folder within.  On the main window, well drag out the following controls: A combo box to contain all of the teams A list box to show the players of the selected team, along with add/delete player buttons A text box tied to the selected players name, with a save button to save any changes made to the player name A combo box of all the available positions, tied to the currently selected players position A data grid tied to the statistics of the currently selected player, with add/delete statistic buttons This monstrosity of a form and its associated project will look like this (dont forget to reference the DataFoundation project from the Presentation project): To get to the visual data binding, as we learned in a previous post, you have to first make sure the project containing your bindable classes is compiled.  Do so, and then open the Data Sources pane to add a reference to the Teams and Positions classes in the DataFoundation project: Why only Team and Position?  Well, we will get to Players from Teams, and Statistics from Players so no need to make an interface for them as well see in a second.  As for Positions, well need a way to bind the dropdown to ALL positions they dont appear underneath any of the other classes so we need to reference it directly.  After adding these guys, expand every node in your Data Sources pane and see how the Team node allows you to drill into Players and then Statistics.  This is why there was no need to bring in a reference to those classes for the UI we are designing: Now for the seriously hard work of binding all of our controls to the correct data sources.  Drag the following items from the Data Sources pane to the specified control on the window design canvas: Team.Name > Teams combo box Team.Players.Name > Players list box Team.Players.Name > Player name text box Team.Players.Statistics > Statistics data grid Position.Name > Positions combo box That is it!  Really?  Well, no, not really there is one caveat here in that the Positions combo box is not bound the selected players position.  To do so, we will apply a binding to the position combo boxs SelectedValue to point to the current players PositionId value: That should do the trick now, all we need to worry about is loading the actual data.  Sadly, it appears as if we will need to drop to code in order to invoke our IO methods to load all teams and positions.  At least Visual Studio kindly created the stubs for us to do so, ultimately the code should look like this: Note the weirdness with the InitializeDataFiles call that is my current means of telling an IO where to load the data for each of the entities.  I havent thought of a more intuitive way than that yet, but do note that all data is loaded from Teams.xml besides for positions, which is loaded from Lookups.xml.   I think that may be all we need to do to at least load all of the data, lets run it and see: Yay!  All of our glorious data is being displayed!  Er, wait, whats up with the position dropdown?  Why is it red?  Lets select the RB and see if everything updates: Crap, the position didnt update to reflect the selected player, but everything else did.  Where did we go wrong in binding the position to the selected player?  Thinking about it a bit and comparing it to how traditional data binding works, I realize that we never set the value member (or some similar property) to tell the control to join the Id of the source (positions) to the position Id of the player.  I dont see a similar property to that on the combo box control, but I do see a property named SelectedValuePath that might be it, so I set it to Id and run the app again: Hey, all right!  No red box around the positions combo box.  Unfortunately, selecting the RB does not update the dropdown to point to Runningback.  Hmmm.  Now what could it be?  Maybe the problem is that we are loading teams before we are loading positions, so when it binds position Id, all of the positions arent loaded yet.  I went to the code behind and switched things so position loads first and no dice.  Same result when I run.  Why?  WHY?  Ok, ok, calm down, take a deep breath.  Get something with caffeine or sugar (preferably both) and think rationally. Ok, gigantic chocolate chip cookie and a mountain dew chaser have never let me down in the past, so dont fail me now!  Ah ha!  of course!  I didnt even have to finish the mountain dew and I think Ive got it:  Data Context.  By default, when setting on the selected value binding for the dropdown, the data context was list_team.  I dont even know what the heck list_team is, we want it to be bound to our team players view source resource instead, like this: Running it now and selecting the various players: Done and done.  Everything read and bound, thank you caffeine and sugar!  Oh, and thank you Visual Studio 2010.  Lets wire up some of those buttons now There has got to be a better way to do this, but it works for now.  What the add player button does is add a new player object to the currently selected team.  Unfortunately, I couldnt get the new object to automatically show up in the players list (something about not using an observable collection gotta look into this) so I just save the change immediately and reload the screen.  Terrible, but it works: Lets go after something easier:  The save button.  By default, as we type in new text for the players name, it is showing up in the list box as updated.  Cool!  Why couldnt my add new player logic do that?  Anyway, the save button should be as simple as invoking MFL.IO.Save for the selected player, like this: MFL.IO.Save((MFL.Player)lbTeamPlayers.SelectedItem, true); Surprisingly, that worked on the first try.  Lets see if we get as lucky with the Delete player button: MFL.IO.Delete((MFL.Player)lbTeamPlayers.SelectedItem); Refresh(); Note the use of the Refresh method again I cant seem to figure out why updates to the underlying data source are immediately reflected, but adds and deletes are not.  That is a problem for another day, and again my hunch is that I should be binding to something more complex than IEnumerable (like observable collection). Now that an example of the basic CRUD methods are wired up, I want to quickly investigate the performance of this beast.  Im going to make a special button to add 30 teams, each with 50 players and 10 seasons worth of stats.  If my math is right, that will end up with 15000 rows of data, a pretty hefty amount for an XML file.  The save of all this new data took a little over a minute, but that is acceptable because we wouldnt typically be saving batches of 15k records, and the resulting XML file size is a little over a megabyte.  Not huge, but big enough to see some read performance numbers or so I thought.  It reads this file and renders the first team in under a second.  That is unbelievable, but we are lazy loading and the file really wasnt that big.  I will increase it to 50 teams with 100 players and 20 seasons each - 100,000 rows.  It took a year and a half to save all of that data, and resulted in an 8 megabyte file.  Seriously, if you are loading XML files this large, get a freaking database!  Despite this, it STILL takes under a second to load and render the first team, which is interesting mostly because I thought that it was loading that entire 8 MB XML file behind the scenes.  I have to say that I am quite impressed with the performance of the LINQ to XML approach, particularly since I took no efforts to optimize any of this code and was fairly new to the concept from the start.  There might be some merit to this little project after all Look out SQL Server and Oracle, use XML files instead!  Next up, I am going to completely pull the rug out from under the UI and change a number of entities in our model.  How well will the code be regenerated?  How much effort will be required to tie things back together in the UI?Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Entity Framework v1 &hellip; Brief Synopsis and Tips &ndash; Part 2

    - by Rohit Gupta
    Using Entity Framework with ASMX Web sErvices and WCF Web Service: If you use ASMX WebService to expose Entity objects from Entity Framework... then the ASMX Webservice does not  include object graphs, one work around is to use Facade pattern or to use WCF Service. The other important aspect of using ASMX Web Services along with Entity Framework is that the ASMX Client is not aware of the existence of EF v1 since the client solely deals with C# objects (not EntityObjects or ObjectContext). Since the client is not aware of the ObjectContext hence the client cannot participate in change tracking since the client only receives the Current Values and not the Orginal values when the service sends the the Entity objects to the client. Thus there are 2 drawbacks to using EntityFramework with ASMX Web Service: 1. Object state is not maintained... so to overcome this limitation we need insert/update single entity at a time and retrieve the original values for the entity being updated on the server/service end before calling Save Changes. 2. ASMX does not maintain object graphs... i.e. Customer.Reservations or Customer.Reservations.Trip relationships are not maintained. Thus you need to send these relationships separately from service to client. WCF Web Service overcomes the object graph limitation of ASMX Web Service, but we need to insure that we are populating all the non-null scalar properties of all the objects in the object graph before calling Update. WCF Web service still cannot overcome the second limitation of tracking changes to entities at the client end. Also note that the "Customer" class in the Client is very different from the "Customer" class in the Entity Framework Model Entities. They are incompatible with each other hence we cannot cast one to the other. However the .NET Framework translates the client "Customer" Entity to the EFv1 Model "customer" Entity once the entity is serialzed back on the ASMX server end. If you need change tracking enabled on the client then we need to use WCF Data Services which is available with VS 2010. ====================================================================================================== In WCF when adding an object that has relationships, the framework assumes that every object in the object graph needs to be added to store. for e.g. in a Customer.Reservations.Trip object graph, when a Customer Entity is added to the store, the EFv1 assumes that it needs to a add a Reservations collection and also Trips for each Reservation. Thus if we need to use existing Trips for reservations then we need to insure that we null out the Trip object reference from Reservations and set the TripReference to the EntityKey of the desired Trip instead. ====================================================================================================== Understanding Relationships and Associations in EFv1 The Golden Rule of EF is that it does not load entities/relationships unless you ask it to explicitly do so. However there is 1 exception to this rule. This exception happens when you attach/detach entities from the ObjectContext. If you detach an Entity in a ObjectGraph from the ObjectContext, then the ObjectContext removes the ObjectStateEntry for this Entity and all the relationship Objects associated with this Entity. For e.g. in a Customer.Order.OrderDetails if the Customer Entity is detached from the ObjectContext then you cannot traverse to the Order and OrderDetails Entities (that still exist in the ObjectContext) from the Customer Entity(which does not exist in the Object Context) Conversely, if you JOIN a entity that is not in the ObjectContext with a Entity that is in the ObjContext then the First Entity will automatically be added to the ObjContext since relationships for the 2 Entities need to exist in the ObjContext. ========================================================= You cannot attach an EntityCollection to an entity through its navigation property for e.g. you cannot code myContact.Addresses = myAddressEntityCollection ========================================================== Cascade Deletes in EDM: The Designer does not support specifying cascase deletes for a Entity. To enable cascasde deletes on a Entity in EDM use the Association definition in CSDL for the Entity. for e.g. SalesOrderDetail (SOD) has a Foreign Key relationship with SalesOrderHeader (SalesOrderHeader 1 : SalesOrderDetail *) if you specify a cascade Delete on SalesOrderHeader Entity then calling deleteObject on SalesOrderHeader (SOH) Entity will send delete commands for SOH record and all the SOD records that reference the SOH record. ========================================================== As a good design practise, if you use Cascade Deletes insure that Cascade delete facet is used both in the EDM as well as in the database. Even though it is not absolutely mandatory to have Cascade deletes on both Database and EDM (since you can see that just the Cascade delete spec on the SOH Entity in EDM will insure that SOH record and all related SOD records will be deleted from the database ... even though you dont have cascade delete configured in the database in the SOD table) ============================================================== Maintaining relationships in Code When Setting a Navigation property of a Entity (for e.g. setting the Contact Navigation property of Address Entity) the following rules apply : If both objects are detached, no relationship object will be created. You are simply setting a property the CLR way. If both objects are attached, a relationship object will be created. If only one of the objects is attached, the other will become attached and a relationship object will be created. If that detached object is new, when it is attached to the context its EntityState will be Added. One important rule to remember regarding synchronizing the EntityReference.Value and EntityReference.EntityKey properties is that when attaching an Entity which has a EntityReference (e.g. Address Entity with ContactReference) the Value property will take precedence and if the Value and EntityKey are out of sync, the EntityKey will be updated to match the Value. ====================================================== If you call .Load() method on a detached Entity then the .Load() operation will throw an exception. There is one exception to this rule. If you load entities using MergeOption.NoTracking, you will be able to call .Load() on such entities since these Entities are accessible by the ObjectContext. So the bottomline is that we need Objectontext to be able to call .Load() method to do deffered loading on EntityReference or EntityCollection. Another rule to remember is that you cannot call .Load() on entities that have a EntityState.Added State since the ObjectContext uses the EntityKey of the Primary (Parent) Entity when loading the related (Child) Entity (and not the EntityKey of the child (even if the EntityKey of the child is present before calling .Load()) ====================================================== You can use ObjContext.Add() to add a entity to the ObjContext and set the EntityState of the new Entity to EntityState.Added. here no relationships are added/updated. You can also use EntityCollection.Add() method to add an entity to another entity's related EntityCollection for e.g. contact has a Addresses EntityCollection so to add a new address use contact.Addresses.Add(newAddress) to add a new address to the Addresses EntityCollection. Note that if the entity does not already exist in the ObjectContext then calling contact.Addresses.Add(myAddress) will cause a new Address Entity to be added to the ObjContext with EntityState.Added and it will also add a RelationshipEntry (a relationship object) with EntityState.Added which connects the Contact (contact) with the new address newAddress. Note that if the entity already exists in the Objectcontext (being part theOtherContact.Addresses Collection), then calling contact.Addresses.Add(existingAddress) will add 2 RelationshipEntry objects to the ObjectStateEntry Collection, one with EntityState.Deleted and the other with EntityState.Added. This implies that the existingAddress Entity is removed from the theOtherContact.Addresses Collection and Added to the contact.Addresses Collection..effectively reassigning the address entity from the theOtherContact to "contact". This is called moving an existing entity to a new object graph. ====================================================== You usually use ObjectContext.Attach() and EntityCollection.Attach() methods usually when you need to reconstruct the ObjectGraph after deserializing the objects as received from a ASMX Web Service Client. Attach is usually used to connect existing Entities in the ObjectContext. When EntityCollection.Attach() is called the EntityState of the RelationshipEntry (the relationship object) remains as EntityState.unchanged whereas when EntityCollection.Add() method is called the EntityState of the relationship object changes to EntityState.Added or EntityState.Deleted as the situation demands. ========================================================= LINQ To Entities Tips: Select Many does Inner Join by default.   for e.g. from c in Contact from a in c.Address select c ... this will do a Inner Join between the Contacts and Addresses Table and return only those Contacts that have a Address. ======================================================== Group Joins Do LEFT Join by default. e.g. from a in Address join c in Contact ON a.Contact.ContactID == c.ContactID Into g WHERE a.CountryRegion == "US" select g; This query will do a left join on the Contact table and return contacts that have a address in "US" region The following query : from c in Contact join a in Address.Where(a1 => a1.CountryRegion == "US") on c.ContactID  equals a.Contact.ContactID into addresses select new {c, addresses} will do a left join on the Address table and return All Contacts. In these Contacts only those will have its Address EntityCollection Populated which have a Address in the "US" region, the other contacts will have 0 Addresses in the Address collection (even if addresses for those contacts exist in the database but are in a different region) ======================================================== Linq to Entities does not support DefaultIfEmpty().... instead use .Include("Address") Query Builder method to do a Left JOIN or use Group Joins if you need more control like Filtering on the Address EntityCollection of Contact Entity =================================================================== Use CreateSourceQuery() on the EntityReference or EntityCollection if you need to add filters during deferred loading of Entities (Deferred loading in EFv1 happens when you call Load() method on the EntityReference or EntityCollection. for e.g. var cust=context.Contacts.OfType<Customer>().First(); var sq = cust.Reservations.CreateSourceQuery().Where(r => r.ReservationDate > new DateTime(2008,1,1)); cust.Reservations.Attach(sq); This populates only those reservations that are older than Jan 1 2008. This is the only way (in EFv1) to Attach a Range of Entities to a EntityCollection using the Attach() method ================================================================== If you need to get the Foreign Key value for a entity e.g. to get the ContactID value from a Address Entity use this :                                address.ContactReference.EntityKey.EntityKeyValues.Where(k=> k.Key == "ContactID")

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