I'm creating a UserControl that contains a Listbox. I want the User to be able to add new Listbox Items through a ButtonClick. Adding the new Items works fine but it seems that my DataTemplate is not applied to the newly added Item.
This is how I assign my DataTemplate:
<ListBox x:Name="UserControlListBox" ItemsSource="{Binding Path=ItemsSource, ElementName=MyCustomListControl}" >
<ListBox.ItemTemplate>
<DataTemplate>
<TextBlock TextTrimming="CharacterEllipsis" Text="{Binding}"
Width="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=ActualWidth}" HorizontalAlignment="Left"/>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
This is how I add a new ListboxItem:
public void AddItem(object listBoxItem)
{
IEnumerable enumerable = ItemsSource;
List<object> asList = enumerable.Cast<object>().ToList();
asList.Add(listBoxItem);
ItemsSource = asList;
}
I need a TextBox around my ListItem-Content in order to use the TextTrimming-Property. It works fine for the Items that are already inside the List that is assigned to the ItemSource Property of my UserControl but not to the ones that are added through the ButtonClick as you can see
here
Related
Solved problem, but still have questions. See end of post, or read on for context.
I'm trying to setup a WPF datagrid which has many templated columns with comboboxes inside of them. In particular I'm having trouble with data-binding.
Data Model
First, I have Entry, which contains 4 properties:
Name
Customer
Color
Type
The most interesting property is Color which has two more sub properties:
ColorString
Index
Goal
I need to create a data grid where each row corresponds to an Entry object. The Customer, Color, and Type properties all have comboboxes that allow for a selection of dynamically populated choices. I need the selected item for each combobox to bind to the entry's respective property.
Screenshot
Questions:
How do I properly set the data contexts for the data grid and for each combobox?
For the data grid, I'm setting the data context programmatically to an instance of ObservableCollection.
private ObservableCollection<Entry> entries = new ObservableCollection<Entry>();
public MainWindow()
{
InitializeComponent();
entries.Add(new Entry("Foo", "Customer1", new MyColor("#00000000", 1), "Type1"));
entries.Add(new Entry("Bar", "Customer2", new MyColor("#00000000", 1), "Type2"));
LayerMapGrid.DataContext = entries; //Set data-context of datagrid
}
For the color combobox, I'm using an ObjectDataProvider in my XAML:
<Window.Resources>
<ObjectDataProvider x:Key="Colors" ObjectType="{x:Type local:MyColor}" MethodName="GetColors"/>
</Window.Resources>
This is how I bind the ObjectDataProvider
<ComboBox ItemsSource="{Binding Source={StaticResource Colors}}"/>
In the MyColor class, I've created the method below:
public static ObservableCollection<MyColor> GetColors()
{
ObservableCollection<MyColor> colors = new ObservableCollection<MyColor>();
//... Fill collection... (omitted for brevity)
return colors;
}
The good news is that ALL of the above code WORKS. However is it a good approach to the problem at hand?
This my next and more important question:
How do I bind the selected items of the comboboxes so that ObservableCollection<Entry> is updated?
I'm aware that I need to set the UpdateSourceTrigger="PropertyChanged", so that my source, which is the Entry collection is updated.
Here is my current XAML code for setting up my entire data grid. Note: I haven't implemented the customer and type comboboxes yet. I'm really just concerned with the color combobox:
<DataGrid ItemsSource="{Binding}" AutoGenerateColumns="False" Name="LayerMapGrid">
<DataGrid.Columns>
<!--Name Column-->
<DataGridTemplateColumn Header="Name">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<Label Content="{Binding Name, UpdateSourceTrigger=PropertyChanged}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
<DataGridTemplateColumn.HeaderStyle>
<Style TargetType="DataGridColumnHeader">
<Setter Property="Control.HorizontalContentAlignment" Value="Center" />
</Style>
</DataGridTemplateColumn.HeaderStyle>
</DataGridTemplateColumn>
<!--Customer Column-->
<DataGridTemplateColumn Header="Customer">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox SelectedItem="{Binding CustomerName, UpdateSourceTrigger=PropertyChanged}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<!--Color Column-->
<DataGridTemplateColumn Header="Color">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox ItemsSource="{Binding Source={StaticResource Colors}}" SelectedItem="{Binding Color, ElementName=LayerMapGrid, UpdateSourceTrigger=PropertyChanged}">
<ComboBox.ItemTemplate>
<DataTemplate>
<DockPanel Margin="2">
<Border DockPanel.Dock="Left" HorizontalAlignment="Right" BorderThickness="1" BorderBrush="Black" Margin="1" Width="10" Height="10">
<Rectangle Name="ColorRec" Fill="{Binding ColorString}"/>
</Border>
<TextBlock Padding="4,2,2,2" Text="{Binding ColorString}" VerticalAlignment="Center"/>
</DockPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<!--Type Column-->
<DataGridTemplateColumn Header="Type">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox SelectedItem="{Binding Type, UpdateSourceTrigger=PropertyChanged}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
Your assistance is greatly appreciated. I've been banging my head on the wall for about 16 hours with this.
-Nick Miller
EDIT:
I found the solution (and as always immediately after requesting help), but I don't understand how it works.
In the XAML, I've changed the combobox binding to be the following:
<ComboBox ItemsSource="{Binding Source={StaticResource Colors}}" SelectedItem="{Binding Color, UpdateSourceTrigger=PropertyChanged}">
What exactly is happening here?
Why is the combobox now referring to the datagrid's data context? Doesn't that get overriden when I set the ItemsSource to point to my ObjectDataProvider?
How do I properly set the data contexts for the data grid and for each combobox?
You don't. Normally in WPF, we set the DataContext property on the UserControl, or Window that we are designing, not on individual controls. In this way, all the controls in the view have access to the data properties.
How do I bind the selected items of the comboboxes so that ObservableCollection is updated?
Again, you don't do what you are doing. Rather than using an ObjectDataProvider, you should just have a property of type ObservableCollection<MyColor> in the code behind and bind to that directly. And you should be binding a public Entries property to the DataGrid.ItemsSource property, not setting the private entries field as the DataContext. You really need to read through the Data Binding Overview page on MSDN for further help with this.
Set the DataContext of MainWindow.xaml to itself (which generally is a not a good idea):
public MainWindow()
{
InitializeComponent();
Entries.Add(new Entry("Foo", "Customer1", new MyColor("#00000000", 1), "Type1"));
Entries.Add(new Entry("Bar", "Customer2", new MyColor("#00000000", 1), "Type2"));
DataContext = this; //Set DataContext to itself so you can access properties here
}
Then in MainWindow.xaml:
<DataGrid ItemsSource="{Binding Entries}" ... />
The DataTemplates in each row of the DataGrid automatically have the relevant item in the data bound collection set as the DataContext, so you automatically get access to the properties from the relevant class. Again... no need to set any DataContexts manually. If you have further questions, please read the linked article, because the answers are there.
UPDATE >>>
Let's be clear about something... I am not your personal mentor, so this will be my last reply.
How do I overcome the combobox inheriting the data context of the data grid?
To data bind to the object that is set as the Window.DataContext, you just need to use a valid Binding Path and some basic logic:
<ComboBox ItemsSource="{Binding DataContext.MyColors, RelativeSource={RelativeSource
AncestorType={x:Type YourLocalPrefix:MainWindow}}}" />
How can I specify datasource for a user control:
<ScrollViewer VerticalScrollBarVisibility="Visible" VerticalAlignment="Stretch">
<ListBox ItemsSource="{Binding}">
<ListBox.ItemTemplate>
<DataTemplate>
<local:ucMyControl />
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</ScrollViewer>
How ucMyControl know what values to take? I realize that lisbox will create as many ucMyControls as there are items in bondong collection?
Also, scrollviewers don't work - I can't get to 3rd control (they are all empty anyway, but I hope you'll give me leads how to bind it).
The control that is instantiated from an ItemTemplate in an ItemsControls (e.g. ListBox) has its DataContext property automatically set to the appropriate item from the Items or ItemsSource collection of the ItemsControl.
So if you for example have a collection of Person objects with properties FirstName and LastName as ListBox items you can bind like this in your UserControl:
<UserControl ...>
<StackPanel>
<TextBlock Text="{Binding Path=FirstName}"/>
<TextBlock Text="{Binding Path=LastName}"/>
</StackPanel>
</UserControl>
You do not need to set the DataContext property explicitly.
I have a ListBox that contains a textbox and a combobox in its datatemplate:
<ListBox Height="147" Margin="158,29,170,0" Name="PitcherListBox" VerticalAlignment="Top" ItemsSource="{Binding SomeCollectionOfObjects}" Background="Black">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBox Text="{Binding Path=Name}" />
<ComboBox ItemsSource="{Binding LocalArrayOfIntsProperty}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I want to bind the listbox to a collection of objects (which I've done successfully), but I want the combobox in the above datatemplate to have its itemssource set to a local property on the window (array of ints). I still want the combobox to have a two-way bind between its selected item and a property on the collection of objects...
I have the following in code:
PitcherListBox.DataContext = this;
Basically in the end, I want the combobox within the listbox to have a different itemssource than the listbox itself. I can't seem to figure out how to change the ComboBox's ItemsSource in XAML. Can someone provide me some feedback? Thanks!
Try this:
<ComboBox ItemsSource="{Binding LocalArrayOfIntsProperty, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type YourWindowTypeHere}}}" />
Note that you need to replace YourWindowTypeHere with the type of the Window containing the LocalArrayOfIntsProperty! Also remember that you will need to define an xml namespace for that type!
I have a list box that requires at least one ComboBox. I couldn't find a way to place the ComboBox in the ItemTemplate I use.
...
<DataTemplate x:Key="parts_template">
<StackPanel Orientation="Horizontal">
<TextBlock .../>
<ComboBox .../>
</StackPanel>
</DataTemplate>
...
<ListBox x:Name="lb_parts" ItemTemplate="{StaticResource parts_template}" .../>
...
How do bind that ComoBox in the DataTemplate to an ObservableCollection in the code behind?
Another thing you could try is subscribe the Loaded event on the ComboBox.
Then you can set the ComboBox.ItemsSource in the EventHandler to MyObservableCollection.
Have a look
XAML:
<DataTemplate x:Key="parts_template">
<StackPanel Orientation="Horizontal">
<TextBlock .../>
<ComboBox Loaded="ComboBox_OnLoaded">
<!-- ComboBox ItemTemplate -->
</ComboBox>
</StackPanel>
</DataTemplate>
C# Code Behind:
private void ComboBox_OnLoaded(object sender, EventArgs e)
{
((ComboBox)sender).ItemsSource = MyObservableCollection;
}
Okay, here is how you can add a ComboBox to the ListBox in the code behind.
Create a ComboBox
ComboBox x = new ComboBox();
If you have a data source that populates the ComboBox then you can just bind that
x.ItemsSource = e.Result;
If you do not and want to manually add items to the ComboBox:
ComboBoxItem y = new ComboBoxItem();
Set the Content of the Item to what you want displayed in the ComboBox
y.Content = "Hello";
Now all that is left, is to add the ComboBoxItem to the ComboBox (only if you are creating the Items manually), and then the ComboBox to the ListBox
x.Items.Add(y);
//testing is my ListBox
testing.Items.Add(x);
You should be able to set the data context to the List itself
lb_Parts.DataContext=myCollection;
Then you should be able to bind to it in the template
<DataTemplate x:Key="parts_template">
<StackPanel Orientation="Horizontal">
<TextBlock .../>
<ComboBox ItemSource={Binding}/>
</StackPanel>
</DataTemplate>
I have the following XAML:
<ListView x:Name="debitOrderItems" ItemsSource="{Binding DebitOrderItems}">
<ListView.ItemTemplate>
<DataTemplate>
<CheckBox x:Name="checkbox" Content="{Binding}" IsChecked="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ListViewItem}}, Path=IsSelected}" />
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Binding a list of items works fine and I get a beautiful listview with checkboxes, but I would like to have them all selected immediately. There is a SelectAll() method on the ListView, but when can I call it? DataContextChanged does not work as I link it before I populat the DebitOrderItems on it.
You can do this in the Loaded event:
public Window()
{
InitializeComponent();
Loaded += delegate
{
_listView.SelectAll();
};
}
That said, I'd question your design. Normally you would have a view model for each item in the list, and you would bind the IsChecked property to a property on that view model.