I have a Listbox with data-binding to payments of a project. When I add a new payment, the payment will be added to the list. The add-page is also used to edit the payments. The event is called, in debug-mode I can see the changed value of my payment, but the ListBoxItem is not going to be updated. At the end of the add-page an event will be called, which updates the listbox items:
GlobalNotifier.OnPaymentAdded();
The OnPaymentAdded calls a method which only notifies about the property changes:
OnNotifyPropertyChanged("Project");
The code of the listbox:
<ListBox Name="ListPayments" ItemsSource="{Binding Project.Payments}">
<ListBox.ItemTemplate>
<DataTemplate>
<Grid Margin="10,5,10,0">
<StackPanel>
<TextBlock FontSize="30" Text="{Binding Name}" />
</StackPanel>
</Grid>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Why are new items added, but existing items not updated? Any idea?
What's happening is that although the Project-object is updated, the Payments object (presumably a List) is not.
What you could try is the following:
Whenever the List-object is being manipulated (edited, items removed / added), fire the PropertyChanged-event for Projects
You can also switch the List<Project> to an ObservableCollection<Project>, which surely will fix your problem
If switching to ObservableCollection is out of the question for you, implement an override for the OnNavigatedTo() in the view that shows the list, and call the PropertyChanged-events (Project, Payments etc) from there.
Either one of these should fix your problem - it's all a matter of taste and preferences.
Sounds like your item properties are not dependency properties, or nobody fires propertychanged for them.
Related
**UPDATED**
Just something quick, hope you guys can help me but i'm having this problem where I open up my wp7 project in blend and i edit the listbox item template and i finish it but. I save everything and go back to VS2010 for Windows phone and hit debug but i look at the phone and i have no items showing up at all. The listbox is just blank.
Code:
<ListBox toolkit:TiltEffect.IsTiltEnabled="True" x:Name="ListBox1" FontSize="42.667" FontFamily="Segoe WP SemiLight" IsSynchronizedWithCurrentItem="False" d:LayoutOverrides="VerticalAlignment">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel x:Name="sp">
<toolkit:ContextMenuService.ContextMenu>
<toolkit:ContextMenu IsZoomEnabled="False" >
<toolkit:MenuItem Header="Delete" Click="Delete_Click" Name="MenuItem1" />
<toolkit:MenuItem Header="Edit" Click="Edit_Click"/>
<toolkit:MenuItem Header="View" Click="View_Click"/>
<toolkit:MenuItem Header="Share.." Click="Share_Click"/>
</toolkit:ContextMenu>
Quick Brief
The app I'm making is a simple note app which saves notes in to a folder in the isolated storage. It successfully retrieves the items but i just want to make it so that it has the title and a brief description. This is all in one item. I've got to that point and the 2 textblocks have ="{Binding}" this basically just adds the title I'm assuming but i also added the ="{Binding}" to the second textblock so its basically showing the title for both of them. Is there a way to bind it to a specific item? like the second textblock, how can i bind that so that it shows 1st 12 characters inside a text file so basically it just shows the title and a brief description?
Maybe you have designtime-only data?
In case you're using Mvvm Light DataService approach, you define 2 DataServices: one for designtime and another for realtime.
Just random assuming. it would be nice to see some sample.
UPD: you posted wrong code, this one is about ContextMenu. I dont see binding there.
But again, generally talking, there shouldnt be any problems. You just deserialize data into model, say
public class Note
{
public string Name {get; set; }
public string Content; {get; set; }
}
And then you have List (or even ObservableCollection if you want realtime changes like renaming). And then you just bind
<TextBlock Text="{Binding Name}"/>
<TextBlock Text="{Binding Content}"/>
If you want to have a strict limit for Content/Description of 12 characters, you can add either Converter and take only 12 first characters, or introduce new property
class Note
{
***
public string Description { get { return Content.Substring(0, 12); } }
}
UPD2:
Ok, lets start from the very beginning. First, MVVM is recommended pattern for Wp7 applications. I believe, you can google info about it yourself, but here are the most important parts:
Model. Keeps your data (in your case, it is notes names and description).
ViewModel. This is abstract view. You have all logic here, you have all data prepared to be rendered here, but VM have no idea how to render data. In your case, a list of notes would be here.
View. Here is description of your ui. In your case, ListBox would be here.
So, first, make a new project, then use NuGet to install latest Mvvm Light (for example). After installing, you should see folders for viewmodels and models.
Create new class Note, like i described before. It would be your model.
Now, go to viewmodel. In a constructor, add a list of Notes there, call it ListOfNotes. Add manually several items to the list and initialize them (add some random values for Names and Contents fields).
Now, go to view. In the top of the file, there should be something like DataContext = "{Binding MainViewModel, Source={StaticResource ViewModelLocator}}". Inside of the view, add ListBox. It should be something like
<ListBox ItemsSource="{Binding ListOfNotes}" >
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding Name}" />
<TextBlock Text="{Binding Content}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
So, what would happen now. When you would run your app, your view would be initialized. It would get MainViewModel (because is it set as DataContext, in step 4). In the constructor of MainViewModel, a ListOfNotes would be initialized (see step 3). Then, when page would load ListBox, it would try to find ListOfNotes inside of DataContext (MainViewModel in our case). It should find your list of Notes, and then, every element of the ListBox would be associated with every element of your ListOfNotes. As it is described in DataTemplate, it would try to get Note.Name and Note.Content.
I have populated a listbox with checkboxes content using this code:
<StackPanel HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Margin="12,105,6,100">
<ListBox Name="ContactResultsData" ItemsSource="{Binding}" Height="393" Margin="0,0,0,0" >
<ListBox.ItemTemplate>
<DataTemplate>
<CheckBox Name="xxx" Content="{Binding Path=DisplayName, Mode=TwoWay}" Unchecked="xxx_Unchecked" Checked="xxx_Checked"></CheckBox>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</StackPanel>
Now I want to check all checkboxes on a button click, please help.
There are 2 options available to you.
Add another (Boolean) property to the object in the collection you are binding to the ItemsSource of the ListBox. You would then bind this to the IsChecked property of the checkbox. Once done, in response to your button click you would just need to iterate over the collection and set all the properties to true, then as long as you are notifying of property changed on the bool the UI will be updated.
You could walk the visual tree of the ListBox looking for checkboxes and checking all that you find.
My descriptions may make option 1 seem like more work but that's what I'd recommend.
I am trying to use the list picker control for wp 7 and caliburn micro. I get the binding correct from the model with conventions, but when I press the the picker to see the page to select somethin gelse I get the message
PID:0E2108CA TID:0F790ABE 2012-04-30 18:02:20.7180 View Model not found. Searched: Microsoft.Phone.Controls, Microsoft.Phone.Controls.ListPickerPageViewModel.
PID:0E2108CA TID:0F790ABE 2012-04-30 18:02:20.7210 View Model not found. Searched: Microsoft.Phone.Controls.IListPickerPageViewModel, Microsoft.Phone.Controls.ListPickerPageViewModel.
and it loads a complete blank page (think its the ListPickerPage in the control toolkit)
it doesnt matter if its bound or not, i guess its some convention hooking in that I dont want.
To reproduce start a new project, hoock up a viewmodel and view, enter below in in your xaml
my xaml looks like this
<toolkit:ListPicker Header="Background" ExpansionMode="FullscreenOnly">
<sys:String>dark</sys:String>
<sys:String>light</sys:String>
<sys:String>dazzle</sys:String>
<toolkit:ListPicker.FullModeItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Margin="16 21 0 20">
<TextBlock Text="{Binding}"
Margin="0 0 0 0"
FontSize="43"
FontFamily="{StaticResource PhoneFontFamilyLight}"/>
</StackPanel>
</DataTemplate>
</toolkit:ListPicker.FullModeItemTemplate>
</toolkit:ListPicker>
What I would like to happen is ofcourse that the property of my model should popuplate the fullscreen selection, and also it would be nice to set the initial selection based on a property on the model.
Some points I noted:
You have to provide an ItemsSource to the ListPicker - A collection of some sort from which it can display the items. In TextBlock text={Binding } - You have to bind some property, so that it can display.
I have a listbox where I create a Itemtemplate with a DataTemplate. I want to be able to write events for the checkboxes and buttons in the datatemplate but they do not seem to be firing.
Here is my xaml and basically I just tried to display a messagebox.show("worked") in the event function.
<ListBox x:Name="ListBox_Items" Margin="0,91,0,8" Foreground="#FF4BE5DB">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal" Width="700">
<CheckBox IsChecked="{Binding needPurchase}" Click="NeedPurchase_Click" Name="CheckBox_NeedPurchase"/>
<CheckBox IsChecked="False" Name="InCart"/>
<StackPanel Orientation="Vertical">
<TextBlock Text="{Binding name}"/>
<TextBlock Text="{Binding storeLocation}"/>
</StackPanel>
<Button HorizontalAlignment="Right" Content="DELETE" Click="Button_Click" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
Because the items are defined within a DataTemplate they are not hooked up to the code-behind for the parent class. If you want to handle events for templated items, then you should consider using commands instead. If you don't know what commands are (and therefore unlikely to know what MVVM is), then you should check out an explanation like this by Jeremy Likness.
I agree that using commands is the best approach.
However if you still want to assess controls placed inside the ItemTemplate/DataTemplate (and subscribe to some events), then you can do this by using the VisualTreeHelper.
For starters you need to remove the name from all the controls in the template. If you have 10 items in the list you will have 10 sets of controls with the same name which won't work.
I have a simple WP7 Programm where I want to switch between displaying my model objects in a ListBox and a Diagramm.
I want to use Data Templates and a Selector Class which returns the correct template.
The selector takes a boolean property in the view model and returns ListBoxTemplate or DiagrammTemplate
My Page Resources looks like this:
<local:NewTemplateSelector x:Key="NewTemplateSelector">
<local:NewTemplateSelector.ListBoxTemplate>
<DataTemplate>
<StackPanel>
<ListBox
x:Name="MainListBox" Margin="6,205,35,136" ItemsSource="{Binding Acts}"
ItemTemplate="{Binding ElementName=Page, Path=Orientation,
Converter={StaticResource OrientationToListItemTemplate}}" />
</StackPanel>
</DataTemplate>
</local:NewTemplateSelector.ListBoxTemplate>
<local:NewTemplateSelector.DiagrammTemplate>
<DataTemplate>
<TextBlock Text="Diagramm"/>
</DataTemplate>
</local:NewTemplateSelector.DiagrammTemplate>
</local:NewTemplateSelector>
My content Panel has only 1 element:
<ContentControl ContentTemplate="{Binding IsDiagramm,
Converter={StaticResource NewTemplateSelector}}" HorizontalAlignment="Left" HorizontalContentAlignment="Left" />
I always get a blank screen when I run this.
My Selector class returns the correct template, I can see this in the debugger.
When I replace the Listbox in the template with a simple textblock, the textblock is displayed, so I suspect a problem with databinding.
But the listbox in the template works fine, when I insert it in my content panel without any data templates.
Any hints for me?
You may like to refer to this thread which discusses nested listboxes.
Listbox Inside listbox Databinding Problem