Binding objects defined in code-behind

Question

I have some object that is instantiated in code behind  for instance  the XAML is called window xaml and within the window xaml cs  protected Dictionary lt string  myClass gt  myDictionary    How can I bind this object to  for example  a list view  using only XAML markups   Update    This is exactly I have in my test code     lt Window x Class  QuizBee Host Window1      xmlns  http   schemas microsoft com winfx 2006 xaml presentation      xmlns x  http   schemas microsoft com winfx 2006 xaml      Title   Binding windowname   Height  300  Width  300      DataContext   Binding RelativeSource  RelativeSource Self    gt       lt Grid gt       lt  Grid gt   lt  Window gt    And in codebehind  public partial class Window1   Window       public const string windowname    ABCDEFG        public Window1                 InitializeComponent              Suppose the title should become  ABCDEFG  right  but it ends up showing nothing

User · Answer

I was having this exact same problem but mine wasn t because I was setting a local variable    I was in a child window  and I needed to set a relative DataContext which I just added to the Window XAML    lt Window x Class  Log4Net Viewer LogItemWindow      xmlns  http   schemas microsoft com winfx 2006 xaml presentation      xmlns x  http   schemas microsoft com winfx 2006 xaml      DataContext   Binding RelativeSource  RelativeSource Self        Title  LogItemWindow  Height  397  Width  572  gt

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That s my way to bind to code behind  see property DataTemplateSelector  public partial class MainWindow   Window     public MainWindow           this DataTemplateSelector   new MyDataTemplateSelector         InitializeComponent                more initializations            public DataTemplateSelector DataTemplateSelector   get              more code stuff        In XAML will referenced by RelativeSource via Ancestors up to containing Window  so I m at my Window class and use the property via Path declaration   lt GridViewColumn Header  quot Value s  quot                  CellTemplateSelector  quot  Binding RelativeSource  RelativeSource FindAncestor  AncestorType  x Type Window    Path DataTemplateSelector  quot   gt    Setting of property DataTemplateSelector before call InitializeComponent depends on missing implementation of IPropertyChanged or use of implementation with DependencyProperty so no communication run on change of property DataTemplateSelector

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Just a little more clarification  A property without  get   set  won t be able to be bound  I m facing the case just like the asker s case  And I must have the following things in order for the bind to work properly      1  Declare a property with  get   set  in code behind public partial class my class Window     public String My Property   get  set              2  Initialise the property in constructor of code behind public partial class my class Window           public my class          My Property    my-string-value        InitializeComponent            3  Set data context in window xaml and specify a binding  lt Window     DataContext   Binding RelativeSource  RelativeSource Self    gt     lt TextBlock Text   Binding My Property    gt   lt  Window gt

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In your code behind  set the window s DataContext to the dictionary  In your XAML  you can write    lt ListView ItemsSource   Binding     gt    This will bind the ListView to the dictionary   For more complex scenarios  this would be a subset of techniques behind the MVVM pattern

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Define a converter   public class RowIndexConverter   IValueConverter       public object Convert  object value  Type targetType                             object parameter  CultureInfo culture                 var row    IDictionary lt string  object gt   value          var key    string  parameter          return row Keys Contains  key     row  key     null             public object ConvertBack  object value  Type targetType                                 object parameter  CultureInfo culture                 throw new NotImplementedException               Bind to a custom definition of a Dictionary  There s lot of overrides that I ve omitted  but the indexer is the important one  because it emits the property changed event when the value is changed  This is required for source to target binding   public class BindableRow   INotifyPropertyChanged  IDictionary lt string  object gt        private Dictionary lt string  object gt   data   new Dictionary lt string  object gt           public object Dummy      Provides a dummy property for the column to bind to               get                       return this                    set                       var o   value                        public object this  string index                 get                       return  data  index                      set                        data  index     value              InvokePropertyChanged  new PropertyChangedEventArgs   Dummy          Trigger update                       In your  xaml file use this converter  First reference it    lt UserControl Resources gt       lt ViewModelHelpers RowIndexConverter x Key  RowIndexConverter   gt   lt  UserControl Resources gt    Then  for instance  if your dictionary has an entry where the key is  Name   then to bind to it  use   lt TextBlock  Text   Binding Dummy  Converter  StaticResource RowIndexConverter   ConverterParameter Name   gt

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There s a much easier way of doing this  You can assign a Name to your Window or UserControl  and then binding by ElementName   Window1 xaml   lt Window x Class  QuizBee Host Window1          x Name  Window1          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml  gt        lt ListView ItemsSource   Binding ElementName Window1  Path myDictionary     gt   lt  Window gt    Window1 xaml cs  public partial class Window1 Window          the property must be public  and it must have a getter  amp  setter     public Dictionary lt string  myClass gt  myDictionary   get  set         public Window1                    define the dictionary items in the constructor            do the defining BEFORE the InitializeComponent             myDictionary   new Dictionary lt string  myClass gt                            item 1   new myClass 1                  item 2   new myClass 2                  item 3   new myClass 3                  item 4   new myClass 4                  item 5   new myClass 5                         InitializeComponent

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While Guy s answer is correct  and probably fits 9 out of 10 cases   it s worth noting that if you are attempting to do this from a control that already has its DataContext set further up the stack  you ll resetting this when you set DataContext back to itself   DataContext   Binding RelativeSource  RelativeSource Self      This will of course then break your existing bindings   If this is the case  you should set the RelativeSource on the control you are trying to bind  rather than its parent   i e  for binding to a UserControl s properties   Binding Path PropertyName           RelativeSource  RelativeSource FindAncestor  AncestorType  x Type UserControl     Given how difficult it can be currently to see what s going on with data binding  it s worth bearing this in mind even if you find that setting RelativeSource  RelativeSource Self  currently works

User · Answer

You can try x Reference trick   lt Window     x Name  myWindow  gt  lt ListBox ItemsSource   Binding Items  Source  x Reference myWindow      gt  lt  Window gt

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Make your property  windowname  a DependencyProperty and keep the remaining same

User · Answer

One way would be to create an ObservableCollection  System Collections ObjectModel  and have your dictionary data in there  Then you should be able to bind the ObservableCollection to your ListBox   In your XAML you should have something like this    lt ListBox ItemsSource   Binding Path Name of your ObservableCollection    gt

User · Answer

You can set the DataContext for your control  form  etc  like so   DataContext   Binding RelativeSource  RelativeSource Self      Clarification   The data context being set to the value above should be done at whatever element  owns  the code behind -- so for a Window  you should set it in the Window declaration   I have your example working with this code    lt Window x Class  MyClass    Title   Binding windowname     DataContext   Binding RelativeSource  RelativeSource Self      Height  470  Width  626  gt    The DataContext set at this level then is inherited by any element in the window  unless you explicitly change it for a child element   so after setting the DataContext for the Window you should be able to just do straight binding to CodeBehind properties from any control on the window

[c#] Binding objects defined in code-behind

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