I have a UserControl in Silverlight. This UserControl looks like this:
<TextBlock Text="{Binding Path=OrderDate}" />
<TextBlock Text="{Binding Path=ShipDate}" />
I have a class that is defined as follows:
public class MyViewModel : ViewModel
{
public string Description { get; set; }
public string Origin { get; set; }
public SlipDetails Details { get; set; }
}
This view model is populated and in the code-behind of my UserControl. I then use this.DataContext = myViewModel; to set the UserControl's DataContext. My problem is, I want to use relative binding in my details grid. I would like to be able to set the DataContext of "detailsGrid" in the XAML to the Details property. Is there a way to do this?
Thanks
I assume that the OrderDate and ShipDate are part of the SlipDetails class?
In that case, you can bind to those fields by using
<TextBlock Text="{Binding Path=Details.OrderDate}" />
<TextBlock Text="{Binding Path=Details.ShipDate}" />
Related
i have a problem with binding an ObservableCollection in XAML
the class :
[DataContract]
public class Result
{
[DataMember]
public string title { get; set; }
[DataMember]
public string href { get; set; }
[DataMember]
public string ingredients { get; set; }
[DataMember]
public string thumbnail { get; set; }
}
the Observable Collection :
private ObservableCollection<Result> resultTest;
the XAML code for binding :
<ListView Name="RecipeListView"
ItemsSource="{Binding resultTest}">
<ListView.ItemTemplate>
<DataTemplate x:DataType="data:Result">
<StackPanel Orientation="Vertical">
<TextBlock Name="RecipeTitleTextBlock"
Text="{Binding title}"
Foreground="Black"
FontSize="24">
</TextBlock>
<Image Name="RecipeImage"
Source="{Binding thumbnail}"
Width="45"
Height="45">
</Image>
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
Everything seems to be correct as application launches, but there is no content visible that I was binding to.
Thanks you guys for any help.
The issue is you're declaring "resultTest" as a "filed", not a property.
However, the binding system uses reflection to look for property, it does not look for "field".
Changing your resultTest declaration to property would solve the issue.
public ObservableCollection<Result> resultTest {get; private set;}
Also, make sure you have the DataContext properly set with xaml or code-behind like
this.DataContext = this
or
this.DataContext = new ViewModel()
Depending on what your DataContext really is.
My full MainWindow.cs looks like below, and the ListView binding works.
public sealed partial class MainPage : Page
{
public ObservableCollection<Result> resultTest { get; private set; }
public MainPage()
{
resultTest = new ObservableCollection<Result>();
resultTest.Add(new Result() { title = "Hello" });
resultTest.Add(new Result() { title = "World" });
this.DataContext = this;
this.InitializeComponent();
}
}
If you have your datacontext set (i.e. in your code behind have datacontext=this or if you are using mvvm have your datacontext set in your window like this
<Window.DataContext>
<local:MainViewModel/>
</Window.DataContext>
And if you have your collection property setup like
public ObservableCollection<Result> resultTest {get;set;}
as Szabolcs Desi suggested then I would try removing the x:Datatype="data:Result" on your DataTemplate. I tested the code you have minus that and it works for me.
Sorry for this dumb question , the problem was I was using a static method that returned an ObservableCollection to a variable. I thought I should remove it to a void function and fill the collection by foreach inside. Everything in xaml was right.
I'm having following classes:
class MyViewModel
{
public List<MyItem> MyItems { get; set; }
public int Width { get; set; }
}
class MyItem
{
public string Name {get; set;}
}
As you see, there's a list of MyItems and Width property in the same class called MyViewModel. How can I bind a single element of that list to a Text property in XAML and Width from ViewModel to XAML's Width property? Here's my try, but I can't at the same time bind those two properties. I mean, I can bind whole list to Text property, but I don't know how could I bind a single item.
<ListView ItemsSource="{Binding MyViewModel}">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Height="15" Width="520">
<TextBlock Width="{Binding Width}" Text="{Binding=MyItems.Name(?)}" />
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
You should revise your design, but here is a quick fix: just introduce a readonly property, that returns the first element, so you will have this (assuming MyItems always has at least element, otherwise you will get an exception):
class MyViewModel
{
public List<MyItem> MyItems { get; set; }
public int Width { get; set; }
public MyItem FirstElement { get { return MyItems[0]; } }
}
In your xaml you bind TextBlock to this property:
<ListView ItemsSource="{Binding MyViewModel}">
<ListView.ItemTemplate>
<DataTemplate>
<Grid Height="15" Width="520">
<TextBlock Width="{Binding Width}" Text="{Binding=FirstElement}" />
</Grid>
</DataTemplate>
</ListView.ItemTemplate>
A little bit offtopic, but still important: viewmodel classes often implement INotifyPropertyChanged, so that views will be able to update themselves automatically. For the same reason List<T> should be replaced with ObservableCollection<T>.
I have searched the web for the last few days but can't seem to find something that I would have thought was quite a simple task. I would like to add a resource in my XAML page of my windows phone application which will reference a complex object but I can't find the correct method. Is this possible? Object is made up something similar to:
Public class ComplexClass
{
Public string name { get; set; }
Public int ID { get; set; }
Public observablecollection<SimpleClass> simpleObjects { get; set; }
Public addSimpleObject(SimpleClass newSimpleObject)
{
if (simpleObjects == null)
simpleObjects = new ObservableCollection<SimpleClass>();
simpleObjects.Add(newSimpleObject);
}
}
Public Class SimpleClass
{
Public String Name { get; set; }
Public String Disc { get; set; }
}
You could use MVVM do achieve this. There are already heaps of tutorials available that you can access to show you how to follow this design pattern, so I won't go into that.
Instead I'll just show you a simple way of getting the data to your view.
In the constructor of your UserControl (or Page or whatever), set up the DataContext to an instance of your ComplexClass:
ComplexClass complexClass;
public MyUserControl1()
{
complexClass = new ComplexClass();
complexClass.AddSimpleObject(new SimpleClass { Name = "Bob" });
this.DataContext = complexClass;
this.InitializeComponent();
}
Then in your XAML you can bind to it like this:
<StackPanel>
<!-- Binding to properties on ComplexClass -->
<TextBlock Text="{Binding Name}" />
<TextBlock Text="{Binding ID}" />
<ListView ItemsSource="{Binding SimpleObjects}">
<ListView.ItemTemplate>
<DataTemplate>
<StackPanel>
<!-- Binding to properties on SimpleClass -->
<TextBlock Text="{Binding Name}" />
<TextBlock Text="{Binding Disc}" />
</StackPanel>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
</StackPanel>
Without knowing specifics of your code, it's hard for me to suggest a method that is most suitable for you. I'd read up on MVVM and view models.
At the moment i try, to build something like that with WPF ! Screenshot: http://i.imgur.com/5G6xBTu.png
I have a ObservableCollection with my "Wecker" Objects. I want to dynamicly add items to the listbox with DataBinding that looks like in the Screenshot. Every try failed so far. What do i need to set in the XAML File??
public static ObservableCollection<Wecker> WeckerCollection = new ObservableCollection<Wecker>();
public ObservableCollection<Wecker> MyWeckerCollection
{
get { return WeckerCollection; }
}
Wecker Class
public class Wecker
{
public ArrayList dayOfWeek { get; set; }
public DateTime Alarm { get; set; }
public bool activated { get; set; }
public bool loop { get; set; }
public int maxRunTime { get; set; }
public int id { get; set; }
public bool schlummern { get; set; }
public bool antiStandby { get; set; }
public bool activateMonitor { get; set; }
public string fileName { get; set; }
public string Mp3 { get; set; }
public string Message { get; set; }
public bool ShowMessage { get; set; }
public int volume { get; set; } }
I tryed that last time:
<ListBox HorizontalAlignment="Left" Height="392" VerticalAlignment="Top" Width="431" Margin="15,89,0,0" ScrollViewer.VerticalScrollBarVisibility="Visible" ItemsSource="{Binding MyWeckerCollection}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<CheckBox IsChecked="{Binding activated, Mode=TwoWay}" />
<Label Content="{Binding Alarm}" />
<Label Content="{Binding dayOfWeek}" />
<Label Content="{Binding Message}" />
<Label Content="{Binding Mp3}" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
I suspect you have not set the DataContext
In the ctor set the DataContext
this.DataContext = this;
or you can do it in XAML in the Window (top) section
DataContext="{Binding RelativeSource={RelativeSource self}}"
If you had set the DataContext then that should work
Are you sure it is in the Windows section
Try (but Path is the default property so that should not be a problem)
ItemsSource="{Binding Path=MyWeckerCollection}"
This may be your problem - public static?
What is the purpose of public static here?
public static ObservableCollection<Wecker> WeckerCollection = new ObservableCollection<Wecker>();
If you want to use a backing property then do it like this
private ObservableCollection<Wecker> myWeckerCollection = new ObservableCollection<Wecker>();
public ObservableCollection<Wecker> MyWeckerCollection
{
get { return myWeckerCollection ; }
}
It sounds like your DataContext is set incorrectly.
You say you are binding the DataContext to {Binding RelativeSource={RelativeSource Self}}, however that just binds the DataContext to the UI object itself.
For example,
<Window DataContext="{Binding RelativeSource={RelativeSource Self}}">
would set the DataContext to the Window object, however the class Window does not have a property called MyWeckerCollection, so your binding would fail.
If you had
<local:MyCustomWindow DataContext="{RelativeSource={RelativeSource Self}}">
and MyCustomWindow has a property called MyWeckerCollection, then it would work.
I also see your comment here which states:
I am not getting any Data at all and i checked the object, "WeckerCollection" it has Data BEFORE setting it as the DataContext
This leads me to believe that either
A) MyWeckerCollection is not a UI control, in which case you need to update your DataContext binding to something other than Self so it correctly binds to your object containing MyWeckerCollection instead of to the UI object.
B) Or this comment can be read as you are setting the DataContext to MyWeckerCollection itself, and of course the class ObservableCollection<Wecker> does not itself have a property called MyWeckerCollection, so the binding would fail.
So the root cause of your problem is the DataContext is not being set correctly.
Unfortunately, the information you provided is not enough for us to help to identify the correct way to set the DataContext, however if you can provide us with more information I'd be glad to help you out.
Often Visual Studio's binding errors and/or Debug mode is enough to point you in the right direction for fixing the DataContext, or there are some 3rd party tools out there like Snoop which I'd highly recommend for debugging binding errors.
Also if you're new to WPF (which it sounds like you are), and are struggling to understand the purpose of the DataContext and how it works, I'd suggest a blog article of mine written for beginners: What is this "DataContext" you speak of?. Its very important that you understand the DataContext if you are going to be working with WPF. :)
Try to add the ItemSource to your ListBox and change the Xaml like this :
Code behind :
this.YourList.ItemsSource = WeckerCollection;
Xaml :
<ListBox HorizontalAlignment="Left" Height="392" VerticalAlignment="Top" Width="431" Margin="15,89,0,0" ScrollViewer.VerticalScrollBarVisibility="Visible">
I have a class called ledgerObject :
public class LedgerObject
{
public ChargeLine ChargeLine{ get; set; }
public DelegateCommand Click_hyperbnCommand{ get; private set; }
public LedgerObject()
{
this.Click_hyperbnCommand = new DelegateCommand(click_btn);
}
private void click_btn(object args)
{
}
}
The chargeLine which is the property of this class is itself a class and has some properties in it.
So I am binding the datacontext of a listbox to an array of LedgerObject, and I want to bind the textblock control defined inside a listboxitem template to the property of a ChargeLine. Any idea or suggestion will help.
I have tried this but not working:
<TextBlock Margin="4 0 4 0" Grid.Column="3" Text="{Binding Path=ChargeLine.SimCode}" TextDecorations="Underline" Foreground="Red" />
You have to use the ItemsSource-Property of the ListBox instead of the DataContext.
// edit
The reasons are explained here and here in more detail.