Develop Reference

Binding Button in DataGrid header to ViewModel

I have a DataGrid that is bound to an ICollectionView "Employees" in my ViewModel, which I want to filter for each column.
Here's what the XAML looks like:
<DataGrid ItemsSource="{Binding Employees}"
attachedBehaviors:DataGridColumnsBehavior.BindableColumns="{Binding EmployeeColumns}">
<DataGrid.ColumnHeaderStyle>
<Style TargetType="DataGridColumnHeader">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="16"/>
</Grid.ColumnDefinitions>
<TextBlock Text="{Binding}" Grid.Column="0"/>
<Button Content="v" Grid.Column="1" Click="ButtonClick"/>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</DataGrid.ColumnHeaderStyle>
</DataGrid>
This works fine and when calling ButtonClick I could pass the data context along to my ViewModel and search for this string. However, what I would prefer is to bind the button to an event in my ViewModel, so I can get a reference to the column from which this event originated and appropriately handle my data there.
My ViewModel looks like this:
class ViewModel : ChangeNotifier
{
public ICollectionView Employees { get; private set; }
public ViewModel()
{
var _employees = new List<Employee>{...
Employees = CollectionViewSource.GetDefaultView(_employees);
EmployeeColumns = new ObservableCollection<DataGridColumn>();
EmployeeColumns.Add(new DataGridTextColumn { Header = "First Name", Binding = new Binding("FirstName") });
EmployeeColumns.Add(new DataGridTextColumn { Header = "Last Name", Binding = new Binding("LastName") });
FilterMenu = new RelayCommand(new Action<object>(FilterContextMenu));
}
private ICommand filtermenu;
public ICommand FilterMenu
{
get
{
return filtermenu;
}
set
{
filtermenu = value;
}
}
public static void FilterContextMenu(object obj)
{
MessageBox.Show("Event Fired!");
}
public ObservableCollection<DataGridColumn> EmployeeColumns { get; private set; }
}
So my question is: How do I bind to the FilterContextMenu event?
I've tried:
<Button Content="v" Grid.Column="1" Command="{Binding FilterMenu}"/>
And also:
<Button Content="v" Grid.Column="1" Command="{Binding FilterMenu, RelativeSource= {RelativeSource FindAncestor, AncestorType={x:Type DataGrid}}}"/>
None of which triggered the event.
Edit: I probably should add that the greater goal is to create a button that, when clicked, creates a dynamically populated context menu. I may be on the completely wrong track here.

I don't follow your description of the greater goal and dynamically populated context menu.
That sounds like it will have it's own set of somewhat more challenging problems getting a reference to any datacontext in the window. A contextmenu usually relies on placement target to get anything contextual because it isn't part of the window.
If you intend passing commands through from that then this could well get quite complicated.
But... that's a different question entirely.
Binding a button to the command which is in the datacontext of the datagrid.
My datagrid is called dg ( I'm a minimalist at heart ).
I got a bit wordy with my command and it's called ColHeaderCommand.
This works for me:
<DataGridTextColumn.Header>
<Button Content="Title" Command="{Binding DataContext.ColHeaderCommand, ElementName=dg}"/>
</DataGridTextColumn.Header>
My viewmodel is the datacontext of the window, which is inherited down to the datagrid.
You will want some sort of a parameter for that command to pass in what column or whatever you're doing whatever with.

Set TextBlock Visibility based on a bound bool

I am trying to link the visibility of a TextBlock to a bool property which is also linked to a checkbox using WPF and c#. I have the following code in two different sections of the same xaml file (one section is a summary, and the other is settings. I am very new to WPF, and am learning as I go. Currently, the TextBlock is visible no matter what the value of IsSecondaryMessageFilePath is.
<TextBlock Name="secondaryfolderinfo" Foreground="Red">
<ContentControl Content="Secondary message folder" Foreground ="Black" />
<ContentControl Content = "{Binding Path=SecondaryMessageFilePath}" ContentStringFormat="" ClipToBounds="False"></ContentControl>
<ContentControl Content = " "></ContentControl>
<TextBlock.Style>
<Style TargetType="{x:Type TextBlock}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=IsSecondaryMessageFilePath}" Value="True">
<Setter Property="Visibility" Value="Visible"></Setter>
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
Further down I have:
<CheckBox IsChecked="{Binding Path=IsSecondaryMessageFilePath, Mode=TwoWay}"
Name="SecondaryPathCheckBox"
VerticalAlignment="Top"
HorizontalAlignment="Left"
Margin="320,7,0,0">Save additional locations</CheckBox>
Finally, in the code-behind, I have:
public bool IsSecondaryMessageFilePath
{
get { return _isSecondaryMessageFilePath; }
set
{
if (_isSecondaryMessageFilePath != value)
{
_isSecondaryMessageFilePath = value;
OnPropertyChanged("IsSecondaryMessageFilePath");
}
}
}
private bool _isSecondaryMessageFilePath;
public string SecondaryMessageFilePath
{
get { return _secondaryMessageFilePath; }
set
{
if (_secondaryMessageFilePath != value)
{
_secondaryMessageFilePath = value;
OnPropertyChanged("SecondaryMessageFilePath");
}
}
}
private string _secondaryMessageFilePath;
Any assistance would be appreciated.
EDIT
Working from the suggestion below, I tried adding the BooleanToVisibilityConverter, but am getting a missing assembly reference for it, and am to new to WPF to figure out how to resolve it. My opening code is as follows:
<UserControl x:Class="Sender_Receiver.SenderReceiverSetup"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:diagnostics="clr-namespace:System.Diagnostics;assembly=WindowsBase"
xmlns:m=...
xmlns:
<UserControl.Resources>
<BooleanToVisibiltyConverter x:Key="BooleanToVisibilityConverter"/>
...

Your code looks ok at first glance, but you really don't need to use a data trigger for this. WPF comes with a BooleanToVisibilityConverter class that you declare in your resources:
<BooleanToVisibiltyConverter x:Key="BooleanToVisibilityConverter"/>
Then in your TextBlock, you bind Visibility:
<TextBlock Visibility="{Binding Path=IsSecondaryMessageFilePath, Converter={StaticResource BooleanToVisibilityConverter}}"/>
Just so you know, there may be a simpler way to do this, just bind to the IsChecked property itself!
<CheckBox x:Name="UseSecondaryPath"/>
<TextBlock Visibility="{Binding ElementName=UseSecondaryPath, Path=IsChecked, Converter={StaticResource BooleanToVisibilityConverter}}"/>
Of course if you need the bool for something else that wouldn't be an ideal solution, but it is a little cleaner if its just for the UI.
The code for a custom BooleanToVisibilityConverter, if you are interested, is:
public class BooleanToVisibilityConverter : IValueConverter
{
public object Convert (object value, ...)
{
if ((bool)value)
return Visibility.Visible;
else
return Visibility.Collapsed;
}
public object ConvertBack(object value, ...)
{
return Binding.DoNothing;
}
}
Let me know if I can clarify anything or assist further.

private Boolean _IsChecked;
//Bind this to your checkbox
public Boolean IsChecked
{
get { return _IsChecked; }
set { _IsChecked= value; OnPropertyChanged("IsChecked"); OnPropertyChanged("TextBoxVis"); }
}
//Bind this to your TextBox's Visibility Property
public Visibility TextBoxVis
{
get { return IsChecked ? Visibility.Visible : Visibility.Collapsed; }
}

Hiding A Listbox Item in WPF

I have a ListBox control populated with several ListBox items. Each item contains a "Proceed" button and a "Postpone" button. I would like to hide that ListBox item (presented as a row in my case) once the "Postpone" button is clicked. The code I have currently doesn't seem to have any effect.
XAML:
<ListBox.ItemContainerStyle>
<Style TargetType="{x:Type ListBoxItem}">
<Style.Triggers>
<DataTrigger Binding="{Binding PostponeClicked}" Value="1">
<Setter Property="IsEnabled" Value="False"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ListBox.ItemContainerStyle>
C#:
private void PostponeThirdPartyUpdatesButton_Click(object sender, RoutedEventArgs e)
{
DataTrigger d = new DataTrigger();
d.Binding = new Binding("PostponeClicked");
d.Value = 1;
var context = ((FrameworkElement)sender).DataContext as Tuple<RegScan_ThirdParty.InstalledApplicationFromRegistryScan, RegScan_ThirdParty.ManifestRequiredApplication, RegScan_ThirdParty.RequiredApplicationState>;
Button ThirdPartyPostponeButton = sender as Button;
ThirdPartyPostponeButton.IsEnabled = false;
if (context != null)
{
RegScan_ThirdParty.registryApplicationPostponeWorkflow(context);
}
ThirdPartyPostponeButton.IsEnabled = true;
}

I had to address the same thing once. Each item in your list box should be an object. We'll call it MyObject for now, since I have no idea what your object type is. In the MyObject class, you'll put your Proceed and Postpone commands.
//ViewModelBase implements INotifyPropertyChanged, which allows us to call RaisePropertyChanged, and have the UI update
class MyObject : ViewModelBase
{
private bool isNotPostponed = true;
public bool IsNotPostponed
{
get { return isNotPostponed; }
set
{
isNotPostponed = value;
RaisePropertyChanged("IsNotPostponed");
}
}
private Command postponeCommand;
public Command PostponeCommand
{
get
{
if (postponeCommand == null)
postponeCommand = new Command(PostponeCommand);
return postponeCommand;
}
}
private void Postpone(object x)
{
IsNotPostponed = false;
}
//similar code for Proceed Command
}
Then in the viewmodel of the view that displays the listBox, create a List that you can bind to your listbox (or whatever collection you want to use). I called it MyObjectsList in the XAML below. (I'm not showing the ViewModel code where this object lives, but I assume you have code for binding to the ListBox.) Then in your ItemsControl.ItemTemplate, bind to each MyObject in your List.
<ItemsControl ItemsSource="{Binding MyObjectsList}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<DataTemplate.Resources>
<BooleanToVisibilityConverter x:Key="boolToVis"/>
</DataTemplate.Resources>
<StackPanel Visibility="{Binding IsNotPostponed, Converter={StaticResource boolToVis}}">
<Button Command="{Binding PostponeCommand}" Content="Postpone"/>
<Button Command="{Binding ProceedCommand}" Content="Proceed"/>
</StackPanel>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
When Postpone is clicked, the command will execute Postpone(), which will set IsNotPostponed to false. On setting IsNotPostponed to false, RaisePropertyChanged tells the UI that IsNotPostponed changed (you need to implement the INotifyPropertyChanged interface.) Lastly, when the UI gets the change notification, it converts the bool to a Visibility. True => Visible, False => Collapsed.

Bind a property in xaml template to viewmodel (RibbonTextBox)

Background info of larger problem
The problem I am trying to solve is to allow a user to set the MinWidth of the label inside of the RibbonTextBox control template. I intend to the same with other properties once I can figure out the first one. The aim of this is to be able to align RibbonTextBoxes stacked on top of each other by setting widths. I am so far solved my problem by hardcoding the values in the control template. I would like to make this control reusable and thus need to be able to set up some binding.
The problem that needs solving
I have the following xaml (lots of xaml has been removed for readability). At the centre of this xaml you can see a label. That label has a MinWidth property which is the focus of my question.
<DataTemplate x:Uid="DataTemplate_0" DataType="{x:Type element:RibbonTextBoxVM}">
<ribbon:RibbonTextBox x:Uid="ribbon:RibbonTextBox_1" IsReadOnly="{Binding IsReadOnly}" Text="{Binding Text}" Label="{Binding Label}" >
<ribbon:RibbonTextBox.Style>
<Style TargetType="{x:Type ribbon:RibbonTextBox}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ribbon:RibbonTextBox}">
<StackPanel Orientation="Horizontal">
<Label Margin='2,0,0,0' Padding='0,0,0,5' BorderThickness='0,0,0,0' HorizontalAlignment='Stretch' VerticalAlignment='Bottom'
HorizontalContentAlignment='Left' VerticalContentAlignment='Top' Background='#00FFFFFF' FlowDirection='LeftToRight'
Visibility='Visible' MinWidth="80">
<!--other stuff-->
</Label>
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</ribbon:RibbonTextBox.Style>
</ribbon:RibbonTextBox>
</DataTemplate>
The following is the viewmodel that backs the above xaml.
public class RibbonTextBoxVM : ViewModel
{
public string Label
{
get { return GetValue(Properties.Label); }
set { SetValue(Properties.Label, value); }
}
public string Text
{
get { return GetValue(Properties.Text); }
set { SetValue(Properties.Text, value); }
}
public bool IsReadOnly
{
get { return GetValue(Properties.IsReadOnly); }
set { SetValue(Properties.IsReadOnly, value); }
}
public RibbonTextBoxVM(string text, string label, bool isReadOnly)
{
Text = text;
Label = label;
IsReadOnly = isReadOnly;
}
}
What I would like to do is have a property LabelMinWidth.
public double LabelMinWidth
{
get { return GetValue(Properties.LabelMinWidth); }
set { SetValue(Properties.LabelMinWidth, value); }
}
I want to allow the user to pass in a value to the constructor to set that property. That is the easy part.
The part I cannot figure out is how to bind my new LabelMinWidth to the MinWidth property of the label inside the control template in the xaml.
If anyone can point me in the right direction that would be great. Ill be happy to answer any questions about the problem.

Since your In your RibbonTextBox has your VM as its DataContext, you can use a Bindingin your ControlTemplate, just like you bound the other properties:
<Label ... MinWidth="{Binding LabelMinWidth}">
This works because in WPF, the DataContext inherits to all children (unless overridden). So if you have a property on your VM that you want to bind to in a control in a template, you just bind to it.

How to disable a button if no items are selected in a ListView

I have a ListView Contained in a UserControl I would like to disabled a button when no items are selected in the UserControl, would it be the right way to do it? So far, it doesn't disable, it just stays enable all the way.
I've included the xaml code.
searchAccountUserControl is the UserControl name property in the xaml.
And AccountListView is the ListView name property in the userControl xaml.
<Button Content="Debit" IsEnabled="true" HorizontalAlignment="Left" Margin="18,175,0,0" Name="DebitButton" Width="128" Grid.Column="1" Height="32" VerticalAlignment="Top" Click="DebitButton_Click">
<Button.Style>
<Style TargetType="Button">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=searchAccountUserControl.AccountListView, Path=SelectedValue}" Value="{x:Null}" >
<Setter Property="Button.IsEnabled" Value="false"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Button.Style>
</Button>
Thanks.
Finally i've used :
in my ViewModel :
private bool _isSelected;
public bool IsSelected { get { return _isSelected; }
set { _isSelected = _account.View.CurrentItem != null;
PropertyChanged.SetPropertyAndRaiseEvent(this, ref _isSelected, value,
ReflectionUtility.GetPropertyName(() => IsSelected)); } }
And then Use isEnabled = "{Binding Path=IsSelected}" in the xaml.

There are a few things wrong here.
Precedence, if you set IsEnabled on the control itself the style will never be able to change it.
ElementName, it's an ElementName, not a path, just one string that gives the name of one element. Everything beyond that goes into the Path.
Style syntax, if you set a Style.TargetType you should not set the Setter.Property with a type prefix (although leaving it does not break the setter).
By the way, this alone is enough:
<Button IsEnabled="{Binding SelectedItems.Count, ElementName=lv}" ...

It's obvious that you aren't using Commanding (ICommand Interface). You should either use that (and preferably the Model-View-ViewModel architecture).
But, if you want to stick with code-behind and XAML:
<ListView SelectionChanged="AccountListView_SelectionChanged" ... />
private void AccountListView_SelectionChanged(Object sender, SelectionChangedEventArgs args)
{
DebitButton.IsEnabled = (sender != null);
//etc ...
}
More information on MVVM: http://msdn.microsoft.com/en-us/magazine/dd419663.aspx
You need to set the DataContext of the View (UserControl) to the instance of the ViewModel you want to use. Then, from there, you can bind to properties on the ViewModel, including ICommands. You can either use RelayCommand (see link above) or use Commanding provided by a framework (for example, Prism provides a DelegateCommand). These commands take an Action (Execute) and a Func (CanExecute). Simply provide the logic in your CanExecute. Of course, you'd also have to have your ListView SelectedItem (or SelectedValue) be databound to a property on your ViewModel so you can check to see if it's null within your CanExecute function.
Assuming you use RelayCommand you don't have to explicitly call the RaiseCanExecuteChanged of an ICommand.
public class MyViewModel : ViewModelBase //Implements INotifyPropertyChanged
{
public MyViewModel()
{
DoSomethingCommand = new RelayCommand(DoSomething, CanDoSomething);
}
public ObservableCollection<Object> MyItems { get; set; }
public Object SelectedItem { get; set; }
public RelayCommand DoSomethingCommand { get; set; }
public void DoSomething() { }
public Boolean CanDoSomething() { return (SelectedItem != null); }
}
<ListView ItemsSource="{Binding MyItems}" SelectedItem="{Binding SelectedItem}" ... />
<Button Command="{Binding DoSomethingCommand}" ... />