I have a user control that has a textbox in it, and i am using a clear button on my main form to clear information from the entire main window. i would like to clear the textbox in the user control once the clear button is clicked as well. i havent found an easy way to do this. i have tried referencing the control's name in c# followed by a "." however the name of the text box does not show up. any help would be appreciated!
WPF declares controls in a UserControl as private. To make your TextBox public you declare it with a FieldModifier as in:
<TextBox x:FieldModifier="Public" />
where x is the xaml namespace xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml". However the recommended way of clearing a TextBox is to bind it to a property and then clear the property.
You should not try to directly access controls within a UserControl from external classes or code. The simple mechanism would be to add a Clear() method to the UserControl which clears all relevant controls and information inside the UserControl.
The textbox could be bound to the DataContext of the UserControl. So a way of clearing it might be setting the property that is bound to the Text property of the TextBox to an empty string.
Related
I want to bind my textboxes in wpf xaml. That is doing perfectly but when i get textbox with his x:Name="myTextbox" in codebehind. He says
"The name 'myTextbox' does not exist in the current context"
Using WPF, you cannot access items by name if there are inside a DataTemplate, like in your case, probably. However is not a good practice to modify the template using code behind. If you want to use correctly WPF, take a look at MVVM pattern.
In your case, the ListBox should be bound to an ObservableCollection and inside the template you can bind your textbox or whatever you have to the Item object.
Don't access the textbox like this : x:Name="myTextbox"
Instead access it like myTextbox.Text = "Hello World";.
I have a accustom control bound to a model class. So if any change in UI for textbox it updates ViewModel.model instance. but it doesnot work the other way. What is the necessary thing I need to look for? or troubleshoot steps pls.
Thanks.
You mean the value is displayed in the Textbox but a new typed value isn't?
If so you need to set two way binding on the Textbox binding:
<Textbox Text={Binding myTextProperty, Mode="TwoWay", UpdateSourceTrigger="ProprtyChanged"/>
This will enable both read & write functionality to your binding.
As #Ganesh says, you also need to make sure you're implementing the INotifyPropertyChanged interface in your ViewModel.
I have situation like this, I have 2 WPF forms developed using MVVM Pattern ..2nd form will be opened from first(form1 will be in backend till form2 is closed) and closing the second makes the first form active.
Now I want to make a textbox on form1 with default focus set on it. I was able to do it with FocusManager and its working fine but the same is not working fine when Im getting into form1 from form2. Also during this time I have to set the focus on the default textbox and also I need to select all the text present on it. I am unable to understand how to do this with viewmodel.
Any suggestions will be of great help for me.
Regards,
Krishna
You can focus a particular UI element using the FocusManager.FocusedElement Attached Property:
<Grid FocusManager.FocusedElement="{Binding ElementName=SomeTextBox}">
<TextBox Name="SomeTextBox" Text="{Binding SomeProperty}" />
</Grid>
This should select the TextBox each time the view/UserControl is loaded.
As for how to select text from the view model... the solution would be the same to handle any event when using MVVM. Wrap it in an Attached Property. Please beware that it is not appropriate to handle all events in the view model, as it should not really have any knowledge of purely UI events. However, the choice is yours.
To 'wrap', or handle any event in an Attached Property, you basically declare a class that extends the DependencyObject class and define one or more static properties. Rather than go over the whole story once again, I'd prefer to direct you to my answer to the What's the best way to pass event to ViewModel? question on Stack Overflow, which provides further links and a full code example.
For background information on Attached Properties, please see the Attached Properties Overview page on MSDN.
I have a few usercontrols loaded into a tabcontrol via MVVM in WPF.
Within the XAML for the usercontrol I am setting focus to a textbox using the FocusManager, however this appears to only work when the first instance of the usercontrol is created.
Just to test I added a loaded event handler to the usercontrol - this is only called on the first instance.
I'm using data templates for the user controls as follows:
<DataTemplate DataType="{x:Type local:UserTypeViewModel}">
<local:UserTypeView />
</DataTemplate>
The textbox is focused as follows:
FocusManager.FocusedElement="{Binding ElementName=txtName}"
Additionally I'm using a global event handler (for the textbox GotFocus event) which selects all the text using a dispatcher.
If anyone has any tips on how to achieve focus with every usercontrol I'd be very grateful.
Thanks, Ben.
Remember that a visual element can only receive focus, if:
It is visible (in a TabControl only one tabitem can be visible at a time
IsFocusable must be set to true (is default false for UserControls)
It has finished loading (as you write - do it in the Loaded event))
I think the first reason is why it only works for the first element.
As for how to achieve it for all controls - you can use a style with an EventSetter for the Loaded event. You need to make a style per type of control though to avoid having to set it for each control.
I've created a simple UserControl in ExpressionBlend. The UserControl is a ractangle with a TextBlock in it. When i use this UserContol in a Silverlight project, i can not change the text in the textBlock of the control. Should give an acces to the TextBlock before using the Control?
HELP"_
Your user control should have public properties that map to its features. If you want the users of the control to be able to set the text, create a Text property. The implementation can be as simple as forwarding to the inner TextBox.
Exposing the inner control is not the right way to do it.