I have a WPF Window that contains a TextBox. I have implemented a Command that executes on Crtl-S that saves the contents of the window. My problem is that if the textbox is the active control, and I have newly edited text in the textbox, the latest changes in the textbox are not commited. I need to tab out of the textbox to get the changes.
In WinForms, I would typically call EndEdit on the form, and all pending changes would get commited. Another alternative is using onPropertyChange binding rather than onValidation, but I would rather not do this.
What is the WPF equivalent to EndEdit, or what is the pattern to use in this type of scenario?
Thanks,
Based on Pwninstein answer, I have now implemented an EndEdit in my common class for WPF Views / Windows that will look for bindings and force an update on them, code below;
Code below;
private void EndEdit(DependencyObject parent)
{
LocalValueEnumerator localValues = parent.GetLocalValueEnumerator();
while (localValues.MoveNext())
{
LocalValueEntry entry = localValues.Current;
if (BindingOperations.IsDataBound(parent, entry.Property))
{
BindingExpression binding = BindingOperations.GetBindingExpression(parent, entry.Property);
if (binding != null)
{
binding.UpdateSource();
}
}
}
for(int i=0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(parent, i);
this.EndEdit(child);
}
}
protected void EndEdit()
{
this.EndEdit(this);
}
In my Save command, I now just call the EndEdit method, and I don't have to worry about other programmers selection of binding method.
To avoid the issue of needing to tab away, you could simply change the UpdateSourceTrigger property of your controls' binding. Try the following:
<TextBox.Text>
<Binding Path="MyProperty" UpdateSourceTrigger="PropertyChanged"/>
</TextBox.Text>
This tells WPF to update the backing object whenever the Text property is changed. This way, you don't need to worry about tabbing away. Hope this helps!
EDIT:
The accepted answer for the following SO question provides a way to automatically run validation rules for a page. You could modify it to call UpdateSource() on all BindingExpression objects instead.
Link
You can force specific bindings to update using code like the following:
var bindingExpression = txtInput.GetBindingExpression(TextBox.TextProperty);
bindingExpression.UpdateSource();
Doing this more generally is difficult because there is no generic way to get all bindings, nor would you necessarily want them all to updated.
I disagree w/ArielBH. The issue here is the interplay between keyboard and logical focus, and unless you have changed all your Data Binding update triggers to PropertyChanged, you may miss some source data updates in certain scenarios (e.g. Toolbar button clicks). For instance, the default update trigger for TextBox.Text is LostFocus and clicking on a toolbar button does not blur the active TextBox focus.
If you have some mechanism to register the controls, then you could explicitly force the data binding to update the source in the same place you'd be calling EndEdit in a WinForms app. It's not neat or elegant, but it gets the job done.
If somebody has come up with a better solution, I'd be all ears as well.
HI,
Well, while using WPF, one needs to adopt to a different mindset.
I would basically bind the TextBox's Text property to one of my properties (Model, ViewModel, Code-Behind, whatever makes you happy).
So when you handle CTRL+S you just go to the clr property that is binded and continue happily with all the data you want.
Hope that help you, if you require code examples, leave me a comment.
Ariel
I believe you are supposed to declare a binding group and then reference that binding group in code. I put mine on the root Window element so it gets the bindings of all the controls on the Window.
<Window.BindingGroup>
<BindingGroup />
</Window.BindingGroup>
this.BindingGroup.CommitEdit();
Related
I was trying to get the text that I wrote in a DataGrid cell after editing it, so I put a breakpoint in the function CellEditEnding and looked at the EventArgs and noticed that it contains the property "Text", so I wouldn't have to do the usual XAML binding hacks to get it.
However, I quickly noticed that it will not let me access it.
After taking a look at the FrameworkElement class, I can confirm that there is no Text property, so what is going on, why can't I acces the property?
why can't I acces the property?
Because a FrameworkElement indeed has no Text property.
TextBox, which derives from FrameworkElement, has a Text property though so you could cast the EditingElement to a TextBox and then access the property:
string text = (e.EditingElement as TextBox)?.Text;
Visual Studio displays the properties of the actual object in memory.
It's a bad idea to use the UI as a data store and try and directly work with it.
You should bind an observablecollection of t to the itemssource of your datagrid and work with each instance of t.
That will be far easier to work with.
As to why are some properties inaccessible?
It's because those properties aren't where you think they are. The DatagridCell has a series of things nested within it.
DataGridCell > Border > ContentPresenter > TextBlock
Download snoop https://github.com/snoopwpf/snoopwpf or install using chocolatey / your preferred method.
Run snoop.
Run your app.
Drag the right gunsight thing over you window.
A window should open up with two panels. Controls and properties.
Mouse over a datagrid cell.
press shift+ctrl and you should see the element under the mouse selected in the ui tree.
A datagrid is pretty complicated and there are multiple things in each row.
See that textblock there?
That's the thing has a text property.
Or at least that's the thing when you're not in edit mode.
Switch to edit mode and I have a TextBoxView.
So one complication is, which are you working with at a given time?
I have heard a lot about two-way bindings in WPF, but I'm not entirely clear on how to accomplish it or what it actually means.
I have a ListView with a bunch of items in it. When the user selects a new item, a TextBox in the application will change its text to display some property of the selected item.
But when the user changes the text in the text box I want the ListView item to be updated immediately as well. Is there any "two-way binding" magical WPF way of accomplishing this?
Mark's answer shows how to accomplish what you want, but you also asked more generally about "how to accomplish [two-way binding] and what it actually means."
One-way binding means that the binding target (e.g. control) will display data from the binding source (e.g. business object), and will update itself as the business object changes, but that changes to the control will not be propagated back to the business object. E.g. if the Person.Name changes from "bob" to "kate", the TextBlock.Text bound to the Name will change from "bob" to "kate" too.
Two-way binding simply means that not only are changes in the business object reflected in the UI, but changes made by the user in the UI are propagated back to the business object too. So now when the user edits the TextBox.Text bound to the Name, say changing "kate" to "edmund", WPF will set the Person.Name property to "edmund" as well.
To accomplish this, just set Mode=TwoWay on the Binding declaration. Some properties bind two-way by default: TextBox.Text, for example, binds TwoWay by default, which is why Mark's code doesn't need the Mode declaration. In addition, as Mark notes, by default WPF only propagates changes back to the business object when the control loses focus. If you have two UI elements bound to the same property, this can mean they appear out of sync, in which case you can use the UpdateSourceTrigger to force WPF to propagate whenever the property changes.
MSDN covers this in detail with some good clear diagrams: see Data Binding Overview in the WPF SDK.
If you haven't you'll need to implement INotifyPropertyChanged for your class that you're binding to.
Also, when you say you want the ListBox item to be updated immediately, you mean that you want it to change as you type in the TextBox. By default the TextBox.Text property updates its source when it loses focus, but you can change this by setting the binding UpdateSourceTrigger to PropertyChanged:
{Binding Source={...}, Path=Whatever, UpdateSourceTrigger=PropertyChanged}
What is the Type of the items in the ListView? To get the two way binding going the need you implement INotifyPropertyChanged...
This might help WPF event property changed?
I'm using a basic TextBox that is bound to an object. Basically, what I want to do is call a method every time the text in the box is edited and the user de-selects the box or when the underlying bound data is edited. What I am using right now is the TextChanged event, but this has a few problems:
It is called when the TextBox is first created, and I don't want this.
It is called every time a new character is added, and I only want it called when the underlying bound data is changed (which seems to be whenever focus shifts from the box).
How can I accomplish this?
EDIT: I've tried several other TextBox properties like Get/LostFocus but they never seem to fire.
Also, I don't want to put this method call in the Setter of the Property, because the underlying data is something that is logically separate from the UI of this project and I don't want any method calls that relate to doing computations for the UI.
The event LostFocus fires when the focus is shifted from the current element. I tried it and its working fine.
As jods says, the best way to bind your TextBox's Text to ViewModel's property. The Code are:
View:
<TextBox x:Name="TextBox1" Text="{Binding Path=Text1,Mode=TwoWay, UpdateSourceTrigger=LostFocus}"/>
ViewModel:
public string Text1
{
get { return _text1; }
set
{
_text1 = value;
RaisePropertyChanged("Text1");
}
}
View code behind:
private void ViewModelPropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "Text1")
{
//Call UI related method...
}
}
In this way, it satisfy your two conditions:
1. Every time when you edit TextBox and lose the focus, Setter of Text1 will be called and ViewModel will raise PropertyChanged event.
2. When underlying Text1 is changed. Text1 will also raise the event so View can know it.
Also it can avoid your two concerns:
1. In the first time binding, only getter of Text1 is called. No event is raised.
2. Setter of Text1 is only called after TextBox is lost focus.
every time the text in the box is edited and the user de-selects the box
Hmmm AFAIK it's a standard behaviour of TextBox if you bind text like that: Text={Binding Property}
when the underlying bound data is edited
You can provide this functionality inside setter of your property.
Best design is to listen for changes in the underlying bound property. You can do that without changing the setter if you use a DependencyProperty or if your object implements INotifyPropertyChanged.
When the underlying property changes (LostFocus by default, or each char at a time) is a binding option.
If you don't want to follow my advice of listenning for changes in your (view-)model, you could subscribe to GotFocus and LostFocus events. Save the current value when you get focus, compare with current value when you lose it. If it's different -> do what it is you want to do.
I am not sure what you are finally trying to achieve but I am going to take a guess at this. If you are following an MVVM pattern then, then it seems like you can achieve what you want by using the updateSourceTrigger property of the binding. If you are not using MVVM then you might what to take a look at using MVVM
I'm trying to create a binding from my custom control to objects that are in a BindingList.
While with textbox, I can easily write
textBox.DataBindings.Add("Text",myBindingList,"PropertyOfObjectOfBindingList")
With my custom property "Value", this thing doesn't work (the object doesn't get updated).
What should I implement with my custom control to make it works? I already implemented INotifyPropertyChanged, but it doesn't work.
I just want make this line works:
customControl.DataBindings.Add("CustomProperty",myBindingList,"PropertyOfObjectOfBindingList")
EDIT 1:
I read this around web: http://kbalertz.com/327413/control-using-Visual.aspx however is not working for me at the moment, maybe I'm doing something wrong
Since you said your bound object doesn't get updated (I assume from Control -> Object changes), but it is bound correctly, maybe this will help:
customControl.DataBindings.Add("CustomProperty", list, "BoundObjectProperty",
false, DataSourceUpdateMode.OnPropertyChanged);
Maybe the Implementing complex data binding in custom controls article will help.
I solved the problem by myself:
While the article I linked is a good suggestion, there is a wrong part; you don't have to create an event in your custom class with PropertyChangedEventHandler, but just with EventHandler.
public event EventHandler CustomPropertyChanged;
Is enough to make everything works. Obviusly you have to call it when your property changes
EDIT 1:
I discovered a bad thing, while on textboxes, if the control lose focus the bindinglist get updated, on my custom controls this thing happens only when I change selected item in listbox.
I don't find a way to solve this at the moment.
In a form, I have a TextBox Binding an Object on its member property "Title". Along with it is a "Save" button to test the binding.
Seems like the underlying object property does not get updated unless the textbox loses focus. But there no form.ActiveControl.Blur() for use. Besides, this does not seem like a sound hack.
Anyway to do this better? Thanks.
EDIT: Sorry for not being clear. My question is in the title: "How to commit a TextBox". I use the term "commit" from the DataGridView commit and BindingSource commit. And it's in WinForms. (Have never worked with WPF, so it didn't occur to me. Sorry).
The actual scenario I have is I have a bunch of TextBox binded to property of a single Object. The user enters values in all the TextBox and when the user clicks save (toolbar button), the last TextBox is still in focus (or in editing mode) hence the save will not capture the last value in the last textbox.
I want to find the correct way to "commit" the textbox value just before saving.
Thanks.
Since the question has been updated to indicate this is WinForms, you'll need to handle things a little differently than if this were a WPF application. Fortunately, it turns out that the solution is very simple.
Whenever the user clicks on the "Save" button (so, say, in your Save button's Click event handler), you need to call the EndEdit method on your BindingSource. This will cause all pending changes to be committed to the underlying data source, exactly what you were hoping to accomplish.
Also see the relevant documentation on MSDN for more details.
Sounds like WPF from the problem description..
You want to change the binding so that it updates when the property value changes instead of when the textbox loses focus (which is the default when binding to TextBox.Text). You can do this by setting the UpdateSourceTrigger property on your binding:
<TextBox Text="{Binding UpdateSourceTrigger=PropertyChanged}"/>