I am trying to set twoway binding on a UserControl that I have created.
When I use the control in Xaml is set the DataContext like so...
<uc:MyUserControl DataContext="{Binding Path=MyObject, Mode=TwoWay}" />
My user control is defined as the following....
<UserControl x:Class="SilverlightApplication1.XText"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
<TextBox x:Name="Text" Text="{Binding}"/>
</Grid>
</UserControl>
The data is displayed correctly, however if I make I change I wanted it to update with TwoWay binding.
I have tried this below, but it errors at runtime since no Path is defined.
<Grid x:Name="LayoutRoot" Background="White">
<TextBox x:Name="Text" Text="{Binding Mode=TwoWay}"/>
</Grid>
</UserControl>
Any ideas on how to get the control inside the usercontrol to twoway bind to the DataContext?
While your above (self-answered) answer seems to fix the problem, I can't help but think this is a problem domain issue. I have a hard time thinking why you'd want to bind directly like that in the first place, especially since it gives you less control over what happens with the data.
Take the following:
<UserControl
x:Class="SilverlightApplication1.XText"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
x:Name="UserControl"
d:DesignHeight="300"
d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
<TextBox x:Name="Text" Text="{Binding Path=Value, ElementName=UserControl, Mode=TwoWay}"/>
</Grid>
</UserControl>
Then in the codebehind:
public partial class XText
{
public static DependencyProperty ValueProperty =
DependencyProperty.Register(
"Value",
typeof(string),
typeof(XText),
new FrameworkPropertyMetadata(null)
);
public string Value
{
get { return ((string)(base.GetValue(XText.ValueProperty))); }
set { base.SetValue(XText.ValueProperty, value); }
}
...
}
Then, when you're ready to use it:
<uc:XText Value="{Binding Path=MyObject, Mode=TwoWay}" />
Yes, it's more code, but it gives you much more control over what happens with Value inside of your UserControl, and makes working with this code much much simpler in the future.
Thoughts?
-Doug
EDIT: fixed a couple typos.
I have found a solution that doesn't require you to give a name to the base control.
When I defined a name for the base UserControl it was creating issues for me when I was adding multiple instances to my Grid, since they were defined as the same name.
This is a combination of my first answer and Doug's answer.
Note the UserControl lacks the name property and the TextBox has no Binding declared in the XAML
XAML
<UserControl
x:Class="SilverlightApplication1.XText"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
mc:Ignorable="d"
d:DesignHeight="300"
d:DesignWidth="400">
<Grid x:Name="LayoutRoot" Background="White">
<TextBox x:Name="MyText"/>
</Grid>
</UserControl>
CodeBehind
public partial class XText
{
public XText()
{
InitializeComponent();
MyText.SetBinding(TextBox.TextProperty, new Binding()
{
Source = this,
Path = new PropertyPath("Value"),
Mode = BindingMode.TwoWay
});
}
public static DependencyProperty ValueProperty =
DependencyProperty.Register(
"Value",
typeof(string),
typeof(XText),
new PropertyMetadata(null)
);
public string Value
{
get { return ((string)(GetValue(ValueProperty))); }
set { SetValue(ValueProperty, value); }
}
...
}
When you are ready to use it do the following
<uc:XText Value="{Binding Path=MyObject, Mode=TwoWay}" />
Ok I think I have come up with a way to get this to work....
First I set a public property in my UserControl's code behind...
public Binding BindingValue
{
set { this.MyTextBox.SetBinding(TextBox.TextProperty, value); }
}
Then in XAML
<uc:MyUserControl BindingValue="{Binding Path=MyObject, Mode=TwoWay}" />
Related
I'm facing an issue that seems recurrent and with a lot of solutions but, I apologize, I cannot/not able apply in my case. Let me summarize the topology: I have a main windows (MainWindow) with a grid and, in the bottom cell I put an user control written by me (UC_StatusMonitor) with a textbox inside the user control (LBL_CONN_Message) where I want to update with result of operations (e.g. "Connected to device X", "Impossible to read data from Y", "Missing fields" etc etc). This is basically used to inform the user if something is right or wrong. I understood I have to use Dependancy to solve this issue but my implementation doesn't work (for sure I missed something).
Let me show the code:
MainWindows.xaml
<Window x:Class="LUX.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:LUX"
mc:Ignorable="d"
Title="LUX" Name ="MainForm" Height="600" Width="800" MinHeight="600" MinWidth="800">
<Border Padding="10">
<Grid Name="Main_Grid">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="160"/>
<ColumnDefinition Width="*" />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="100"/>
<RowDefinition Height="*"/>
<RowDefinition Height="22"/>
</Grid.RowDefinitions>
<!-- others controls .... -->
<!-- Monitor -->
<StackPanel Name="Stack_Monitor" Grid.Row="2" Grid.Column="1">
<Grid Name="BottomBar" Height="20">
<local:UC_StatusMonitor Height="100" Grid.Row="2" Grid.Column="1"/>
</Grid>
</StackPanel>
</Grid>
</Border>
</Window>
Then the code for the Control
UC_StatusMonitor.xaml
<UserControl x:Class="LUX.UC_StatusMonitor"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:LUX"
mc:Ignorable="d"
xmlns:diag="clr-namespace:System.Diagnostics;assembly=WindowsBase"
d:DesignHeight="20" d:DesignWidth="300">
<Grid Name="UCR_Base" Background="White">
<WrapPanel>
...
<TextBox Name="LBL_CONN_Message" Margin = "10 0 0 0" VerticalAlignment="Center" IsReadOnly="True" BorderThickness="0" Text="{Binding MyTextProperty, ElementName=control}"/>
...
</WrapPanel>
</Grid>
</UserControl>
UC_StatusMonitor.xaml.cs
namespace LUX {
/// <summary>
/// Interaction logic for StatusMonitor.xaml
/// </summary>
public partial class UC_StatusMonitor : UserControl
{
Button[] MenuButtons;
//// The dependency property which will be accessible on the UserControl
public static readonly DependencyProperty MyTextPropertyProperty = DependencyProperty.Register("MyTextProperty", typeof(string), typeof(UC_StatusMonitor), new UIPropertyMetadata(String.Empty));
public string MyTextProperty
{
get { return (string)GetValue(MyTextPropertyProperty); }
set { SetValue(MyTextPropertyProperty, value); }
So, I'm expecting that, everywhere (in all the classes into the workspace, I declared a status monitor static object), I should use an instruction like
MyTextProperty = "Connected";
and then see this message on the textbox into user control.
Obviously, doesn't happen :(
Thanks and best regards
I have managed to get the UserControl to work with Binding.
Here is how I have done it:
UserControlWithBinding.xaml:
<UserControl x:Class="SO_app.UserControlWithBinding"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:SO_app"
mc:Ignorable="d"
d:DesignHeight="20" d:DesignWidth="300">
<Grid Name="IAmGroot"> <!-- Name this grid as you want as this is what we will use for internal Binding -->
<TextBlock Text="{Binding Status}"/><!-- Because this grid is bound to the control it self you will always use this property, unless you rename it :-) -->
</Grid>
Now the code behind of the UserControlWithBinding.xaml.cs:
/// <summary>
/// Interaction logic for UserControlWithBinding.xaml
/// </summary>
public partial class UserControlWithBinding : UserControl
{
public UserControlWithBinding()
{
InitializeComponent();
IAmGroot.DataContext = this;// this is where we set the data context for the grid so it uses the UserControl and not the inherited one. This will allow us to have the DataContext for User Control to be still inherited but the grid will look into a UserControl as an object to assign it to it's data context.
}
public string Status
{
get { return (string)GetValue(StatusProperty); }
set { SetValue(StatusProperty, value); }
}
// Using a DependencyProperty as the backing store for Status. This enables animation, styling, binding, etc...
public static readonly DependencyProperty StatusProperty =
DependencyProperty.Register("Status", typeof(string), typeof(UserControlWithBinding), new PropertyMetadata(null));//note that I am using null and not string.Empty
}
Now let's use our control in xaml:
<local:UserControlWithBinding Status="{Binding PropertyThatYouWantToBindThisControlsText}"/>
This should solve your problem.
I am very new to wpf and I would like to create a simple user control that consists of a textblock and a textbox so that I can reuse it. However, I do not really know how to bind the content of the textblock so that it can be set from outside and expose the textbox so that it could be bound to other field from the outside calling xaml.
The following is the code for my user control
<UserControl x:Class="WPFLib.UserControlLibs.TextBoxUsrCtrl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WPFLib.UserControlLibs"
mc:Ignorable="d"
d:DesignHeight="20"
d:DesignWidth="300">
<StackPanel Orientation='Horizontal'
Width='{Binding ActualWidth, ElementName=parentElementName}'
Height='{Binding ActualWidth, ElementName=parentElementName}'>
<Grid HorizontalAlignment='Stretch'>
<Grid.ColumnDefinitions>
<ColumnDefinition Width='1*' />
<ColumnDefinition Width='1*' />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<TextBlock Text='{Binding Text, ElementName=parentElementName}'
Background='Aqua'
Grid.Column='0'
Grid.Row='0' />
<TextBox x:Name='UserTxBox'
Grid.Column='1'
Grid.Row='0'
Background='Red'
HorizontalAlignment='Stretch'
Text='this is a test to see how it works' />
</Grid>
</StackPanel>
</UserControl>
How do I expose the Text from the TextBlock and TextBox so that it could be set and retrieved from the calling xaml?
For example
<Window x:Class="TestWPF.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:TestWPF"
xmlns:controls='clr-namespace:WPFLib.UserControlLibs'
` mc:Ignorable="d"
Title="MainWindow"
Height="350"
Width="525"
WindowState='Maximized'
FontSize='18'>
<StackPanel>
<controls:TextBoxUsrCtrl Width='500' HorizontalAlignment='Left' **Text='NEED TO SET THE TEXT BLOCK HERE'**/>
</StackPanel>
</Window>
You should give it two dependency properties, one for each of the two text properties you want to expose (this is a horrible amount of boilerplate; I use Visual Studio's snippet feature to generate it all). Then in the UserControl XAML, you bind control properties to those.
public partial class TextBoxUsrCtrl : UserControl
{
public TextBoxUsrCtrl()
{
InitializeComponent();
}
#region Text Property
public String Text
{
get { return (String)GetValue(TextProperty); }
set { SetValue(TextProperty, value); }
}
public static readonly DependencyProperty TextProperty =
DependencyProperty.Register(nameof(Text), typeof(String), typeof(TextBoxUsrCtrl),
new FrameworkPropertyMetadata(null) {
// It's read-write, so make it bind both ways by default
BindsTwoWayByDefault = true
});
#endregion Text Property
#region DisplayText Property
public String DisplayText
{
get { return (String)GetValue(DisplayTextProperty); }
set { SetValue(DisplayTextProperty, value); }
}
public static readonly DependencyProperty DisplayTextProperty =
DependencyProperty.Register(nameof(DisplayText), typeof(String), typeof(TextBoxUsrCtrl),
new PropertyMetadata(null));
#endregion DisplayText Property
}
XAML. I simplified this so the layout works as I think you intended.
Note how the bindings use RelativeSource={RelativeSource AncestorType=UserControl} to bind to the dependency properties we defined above on the UserControl. By default, Binding will bind to properties of UserControl.DataContext, but we're not using that. The reason is that if we set UserControl.DataContext here, that will break the viewmodel property bindings in the final XAML fragment at the end of this answer. Those bindings will look for those properties on our control. There are workarounds but it gets ugly. The way I've done it here is best because it never breaks anybody's assumptions about DataContext inheritance.
<UserControl
x:Class="WPFLib.UserControlLibs.TextBoxUsrCtrl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:local="clr-namespace:WPFLib.UserControlLibs"
mc:Ignorable="d"
d:DesignHeight="20"
d:DesignWidth="300"
>
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width='*' />
<ColumnDefinition Width='*' />
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*" />
</Grid.RowDefinitions>
<TextBlock
Text='{Binding DisplayText, RelativeSource={RelativeSource AncestorType=UserControl}}'
Background='Aqua'
Grid.Column='0'
Grid.Row='0'
/>
<TextBox
x:Name='UserTxBox'
Grid.Column='1'
Grid.Row='0'
Background='Red'
HorizontalAlignment='Stretch'
Text='{Binding Text, RelativeSource={RelativeSource AncestorType=UserControl}}'
/>
</Grid>
</UserControl>
Usage in window, bound to viewmodel properties:
<local:TextBoxUsrCtrl
Text="{Binding TestText}"
DisplayText="{Binding ShowThisText}"
/>
Lastly, I'm not sure what you were getting at with ElementName=parentElementName. If that's meant to be a reference to a parent control, you can't do that, and it wouldn't be a good idea if you could. You wouldn't want a UserControl constrained by a requirement that a parent control must have a particular name. The answer to that requirement is simply that controls in XAML are only responsible for sizing themselves if they have a fixed size. If they should size to the parent, the parent is always the one responsible for that. So if you want to size two instances of TextBoxUsrCtrl to two different parents, that's fine. Each parent sizes its own children as it pleases.
I made a user control
<UserControl x:Class="MyApp.MyControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d" x:Name="uc">
<Grid Width="Auto" Height="Auto">
<TextBlock Text="{Binding Path=DataContext.TextContent, ElementName=uc}"/>
<TextBlock Text="{Binding Path=DataContext.TextContent2, ElementName=uc}"/>
</Grid>
I want the sub-controls in the defined control(uc) will bind to the properties of uc.DataContext. I used the defined control as follows:
<Window x:Class="Tms.TMSClient.Views.MainWindow" Name="window"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:control="clr-namespace:MyApp"
xmlns:ribbon="clr-namespace:Microsoft.Windows.Controls.Ribbon;assembly=RibbonControlsLibrary">
<control:MyControl DataContext="{Binding Path=MyControlVM}"/>
The DataContext which is assigned to the window has this structure: WindowVM.MyControlVM.TextContent.
The given code does not work because the textbox's DataContext is bound to WindowVM instead. I think the problem may be because the inner textbox is bound before the defined control (uc) is, thus the bounded DataContext for uc does not take effect yet.
What I want is: the custom control (MyControl) will be bound to its corresponding viewmodel (MyControlVM), and the inner elements of MyControl will be bound to the properties of MyControlVM.
Do you have any solutions for this problem?
If I understand you correctly, you want to data bind a property from your MyControl view model to a TextBox.Text property inside the MyControl UserControl. If that is correct, then you can use a RelativeSource Binding, or the ElementName syntax that you are already using.
First, make sure that your view model is set as the DataContext for the UserControl:
public MyControl()
{
DataContext = new YourControlViewModel();
}
As child controls automatically inherit their parent's DataContext objects, you can now reference this view model from the TextBox through the MyControl.DataContext property from the UserControl's XAML:
<TextBlock Text="{Binding DataContext.TextContent,
RelativeSource={RelativeSource AncestorType={x:Type Window}}}" />
That's all you need.
<TextBlock Text="{Binding Path=TextContent}"/>
works for me in my test-application.
MainWindow.xaml
<Window x:Class="DataContextTest.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:my="clr-namespace:DataContextTest"
Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
<my:MyOuterDataContext />
</Window.DataContext>
<Grid>
<my:MyControl DataContext="{Binding Path=MyInnerDataContext}" />
</Grid>
MyControl.xaml
<UserControl x:Class="DataContextTest.MyControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300">
<Grid>
<TextBlock Text="{Binding Path=TextContent}" />
</Grid>
DataContexts:
public class MyOuterDataContext
{
public MyInnerDataContext MyInnerDataContext { get; set; }
public MyOuterDataContext()
{
MyInnerDataContext = new MyInnerDataContext();
}
}
public class MyInnerDataContext
{
public string TextContent { get { return "foo"; } }
}
By default every control inherits its DataContext from its parent control. Thus there is no need to explicitly bind to it.
Indeed, when you want to bind a control's DataContext to a nested property then you have to specifiy this:
<control:MyControl DataContext="{Binding Path=TextContent}"/>
My solution is implemented in MVVM. The view is a window which hosts a usercontrol. I have created a dependency property for this userControl as below :
public static DependencyProperty ListProperty = DependencyProperty.Register(
"ItemsList", typeof(List<RequiredClass>), typeof(UsercontrolTest));
public List<RequiredClass> ItemsList
{
get { return (List<RequiredClass>)GetValue(ListProperty); }
set
{
SetValue(ListProperty, value);
}
}
This property is bound to my viewmodel property (ListOfItems) in xaml :
<Window x:Class="TestProject.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:Test="clr-namespace:TestProject"
Title="MainWindow" Height="350" Width="525">
<Grid>
<Grid.RowDefinitions>
<RowDefinition></RowDefinition>
<RowDefinition></RowDefinition>
</Grid.RowDefinitions>
<Test:UserControlTest Grid.Row="0" ItemsList="{Binding Path=ListOfItems}" />
<Button Grid.Row="1" Content="AddItems" Click="Button_Click" />
</Grid>
</Window>
Also I have initialized the datacontext of the window in codebehind to the viewmodel. Problem is the binding never seems to happen and the set property is never called for the dependency property. Am I missing something here?
Those getters and setters are never called by the binding system (hence you should never place additional code there). The property is probably being set but unless you do something with it in the declaration of the UserControl nothing will be displayed. e.g.
<UserControl Name="control" ...>
<ItemsControl ItemsSource="{Binding ItemsList, ElementName=control}" />
</UserControl>
Why doesn't this binding update?
code:
MainWindow.xaml
<Window x:Class="WpfApplication12.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication12"
Height="350" Width="525">
<StackPanel>
<local:UserControl1 x:Name="usr" />
<TextBlock Text="{Binding ElementName=usr, Path=txt.Text}" />
</StackPanel>
</Window>
UserControl1.xaml
<UserControl x:Class="WpfApplication12.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<TextBox Text="qwe" x:Name="txt" />
</UserControl>
The TextBox inside the UserControl is inaccessible due to its protection level, also it is a field, you can never bind to those. You would need to expose it in the code behind of the UserControl as public property.
public TextBox Txt
{
get { return txt; }
}
Edit: As Henk Holterman pointed out you might not want to expose the whole TextBox, so you could define a dependency property to which the TextBox internally binds for example.