How to display default text --Select Team -- in combo box on pageload in WPF

Question

In a WPF app  in MVP app  I have a combo box for which I display the data fetched from Database  Before the items added to the Combo box  I want to display the default text such as       -- Select Team --    so that on pageload it displays and on selecting it the text should be cleared and the items should be displayed   Selecting data from DB is happening  I need to display the default text until the user selects an item from combo box   Please guide me

User · Answer

I dont know if it s directly supported but you could overlay the combo with a label and set it to hidden if the selection isn t null   eg    lt Grid gt      lt ComboBox Text  Test  Height  23  SelectionChanged  comboBox1 SelectionChanged  Name  comboBox1  VerticalAlignment  Top  ItemsSource   Binding Source ABCD      gt      lt TextBlock IsHitTestVisible  False  Margin  10 5 0 0  Name  txtSelectTeam  Foreground  Gray  Text  Select Team      gt  lt  TextBlock gt   lt  Grid gt    Then in the selection changed handler      private void comboBox1 SelectionChanged object sender  SelectionChangedEventArgs e        txtSelectTeam Visibility   comboBox1 SelectedItem    null   Visibility Visible   Visibility Hidden

User · Answer

Not best practice  but works fine      lt ComboBox GotFocus  Focused   x Name  combobox1  HorizontalAlignment  Left  Margin  8 29 0 0  VerticalAlignment  Top  Width  128  Height  117   gt    Code behind  public partial class MainWindow   Window       bool clearonce   true      bool fillonce   true      public MainWindow                 this InitializeComponent                      combobox1 Items Insert 0    -- Select Team --            combobox1 SelectedIndex   0             private void Focused object sender  RoutedEventArgs e                    if clearonce                                combobox1 Items Clear                    clearonce   false                            if  fillonce                                fill the combobox items here                  for  int i   0  i  lt  10  i                                          combobox1 Items Insert i  i                                     fillonce   false

User · Answer

Easiest way is to use CompositeCollection to merge default text and data from database directly in ComboBox e g        lt ComboBox x Name  SelectTeamComboBox  SelectedIndex  0  gt           lt ComboBox ItemsSource gt               lt CompositeCollection gt                   lt ComboBoxItem Visibility  Collapsed  gt -- Select Team -- lt  ComboBoxItem gt                   lt CollectionContainer Collection   Binding Source  StaticResource ResourceKey MyComboOptions     gt               lt  CompositeCollection gt           lt  ComboBox ItemsSource gt       lt  ComboBox gt    And in Resources define StaticResource to bind ComboBox options to your DataContext  because direct binding in CollectionContainer doesn t work correctly    lt Window Resources gt       lt CollectionViewSource Source   Binding   x Key  MyComboOptions    gt   lt  Window Resources gt    This way you can define your ComboBox options only in xaml e g        lt ComboBox x Name  SelectTeamComboBox  SelectedIndex  0  gt           lt ComboBox ItemsSource gt               lt CompositeCollection gt                   lt ComboBoxItem Visibility  Collapsed  gt -- Select Team -- lt  ComboBoxItem gt                   lt ComboBoxItem  gt Option 1 lt  ComboBoxItem gt                   lt ComboBoxItem  gt Option 2 lt  ComboBoxItem gt               lt  CompositeCollection gt           lt  ComboBox ItemsSource gt       lt  ComboBox gt

User · Answer

HappyNomad s solution was very good and helped me eventually arrive at this slightly different solution     lt ComboBox x Name  ComboBoxUploadProject       Grid Row  2      Width  200       Height  23                                 Margin  64 0 0 0      ItemsSource   Binding projectList       SelectedValue    Binding projectSelect        DisplayMemberPath  projectName      SelectedValuePath  projectId       gt       lt ComboBox Template gt           lt ControlTemplate TargetType  ComboBox  gt               lt Grid gt                   lt ComboBox x Name  cb                       DataContext   Binding RelativeSource  RelativeSource TemplatedParent                         ItemsSource   Binding ItemsSource  RelativeSource  RelativeSource TemplatedParent                        SelectedValue    Binding SelectedValue  RelativeSource  RelativeSource TemplatedParent                         DisplayMemberPath  projectName                      SelectedValuePath  projectId                        gt                   lt TextBlock x Name  tb  Text  Select Item     Margin  3 3 0 0  IsHitTestVisible  False  Visibility  Hidden   gt               lt  Grid gt               lt ControlTemplate Triggers gt                   lt Trigger SourceName  cb  Property  SelectedItem  Value   x Null   gt                       lt Setter TargetName  tb  Property  Visibility  Value  Visible   gt                   lt  Trigger gt               lt  ControlTemplate Triggers gt           lt  ControlTemplate gt       lt  ComboBox Template gt   lt  ComboBox gt

User · Answer

Put a label on top of the combobox   Bind the content of the label to to the combobox Text property   Set the opacity of the combobox to zero   Opacity 0   Write default text in the combobox Text property                     lt ComboBox Name  quot cb quot          Text  quot --Select Team-- quot  Opacity  quot 0 quot           Height  quot 40 quot  Width  quot 140 quot   gt            lt ComboBoxItem Content  quot Manchester United quot    gt            lt ComboBoxItem Content  quot Lester quot    gt        lt  ComboBox gt    lt  Grid gt

User · Answer

A little late but    A more simple way would be to add a dummy data item to the list with parameter IsDummy true and make sure it is not HitTestVisable and its hight is 1 pixel  using a Converter  so it wont be seen   Than just register to SelectionChanged and in it  set the index to the dummy item index   It works like a charm and this way you don t mess with the style and colors of the ComboBox or your application theme

User · Answer

I am using an IsNullConverter class in my project and it worked for me  here is the code for it in c  create a folder named Converter and add this class in that folder as the trigger used doesnt supports value for rather than null and IsNullConverter just do that   public class IsNullConverter   IValueConverter       public object Convert object value  Type targetType  object parameter  CultureInfo culture                return  value    null              public object ConvertBack object value  Type targetType  object parameter  CultureInfo culture                throw new InvalidOperationException  IsNullConverter can only be used OneWay               add the namespace in xaml file like this   xmlns Converters  clr-namespace TymeSheet Converter    means  xmlns Converters  clr-namespace YourProjectName Converter    use this line below the resources to make it availabe through xaml code   lt Converters IsNullConverter x Key  isNullConverter    gt    here is the xaml code i used here the trigger so whenever an item is selected in the combobox the visibilty of your text becomes false    lt TextBlock Text  Select Project  IsHitTestVisible  False  FontFamily   TimeSheet component Resources  Open Sans  FontSize  14  Canvas Right  191  Canvas Top  22  gt                           lt TextBlock Resources gt                               lt Converters IsNullConverter x Key  isNullConverter   gt                           lt  TextBlock Resources gt                           lt TextBlock Style gt                               lt Style TargetType  TextBlock  gt                                   lt Style Triggers gt                                       lt DataTrigger Binding   Binding ElementName ProjectComboBox Path SelectedItem Converter  StaticResource isNullConverter    Value  False  gt                                           lt Setter Property  Visibility  Value  Hidden   gt                                       lt  DataTrigger gt                                   lt  Style Triggers gt                               lt  Style gt                           lt  TextBlock Style gt                       lt  TextBlock gt

User · Answer

IceForge s answer was pretty close  and is AFAIK the easiest solution to this problem  But it missed something  as it wasn t working  at least for me  it never actually displays the text    In the end  you can t just set the  Visibility  property of the TextBlock to  Hidden  in order for it to be hidden when the combo box s selected item isn t null  you have to SET it that way by default  since you can t check not null in triggers  by using a Setter in XAML at the same place as the Triggers   Here s the actual solution based on his  the missing Setter being placed just before the Triggers    lt ComboBox x Name  combo   gt   lt TextBlock Text  --Select Team--  IsHitTestVisible  False  gt       lt TextBlock Style gt           lt Style TargetType  TextBlock  gt                lt Style Setters gt                   lt Setter Property  Visibility  Value  Hidden   gt               lt  Style Setters gt                lt Style Triggers gt                   lt DataTrigger Binding   Binding ElementName combo Path SelectedItem   Value   x Null   gt                       lt Setter Property  Visibility  Value  Visible   gt                   lt  DataTrigger gt               lt  Style Triggers gt           lt  Style gt       lt  TextBlock Style gt   lt  TextBlock gt

User · Answer

Only set the IsEditable attribute to true   lt ComboBox Name  comboBox1                        Text  --Select Team--            IsEditable  true    lt ---- that s all            IsReadOnly  true   gt

User · Answer

You can do this without any code behind by using a IValueConverter    lt Grid gt      lt ComboBox        x Name  comboBox1         ItemsSource   Binding MyItemSource      gt      lt TextBlock        Visibility   Binding SelectedItem  ElementName comboBox1  Converter  StaticResource NullToVisibilityConverter           IsHitTestVisible  False         Text      Select Team        gt   lt  Grid gt    Here you have the converter class that you can re-use   public class NullToVisibilityConverter   IValueConverter        region Implementation of IValueConverter      public object Convert object value  Type targetType  object parameter  CultureInfo culture                return value    null   Visibility Visible   Visibility Collapsed             public object ConvertBack object value  Type targetType  object parameter  CultureInfo culture                throw new NotImplementedException                endregion     And finally  you need to declare your converter in a resource section    lt Converters NullToVisibilityConverter x Key  NullToVisibilityConverter    gt    Where Converters is the place you have placed the converter class  An example is   xmlns Converters  clr-namespace MyProject Resources Converters    The very nice thing about this approach is no repetition of code in your code behind

User · Answer

Not tried it with combo boxes but this has worked for me with other controls     ageektrapped blogpost  He uses the adorner layer here to display a watermark

User · Answer

InitializeComponent   yourcombobox text   -- Select Team --     The above code demonstrates the simplest way to achieve it  After window load  declare the text of the combobox  using the  Text property of the combobox  This can be extended to the DatePicker  Textbox and other controls as well

User · Answer

Based on IceForge s answer I prepared a reusable solution   xaml style    lt Style x Key  ComboBoxSelectOverlay  TargetType  TextBlock  gt       lt Setter Property  Grid ZIndex  Value  10   gt       lt Setter Property  Foreground  Value   x Static SystemColors GrayTextBrush    gt       lt Setter Property  Margin  Value  6 4 10 0   gt       lt Setter Property  IsHitTestVisible  Value  False   gt       lt Setter Property  Visibility  Value  Hidden   gt       lt Style Triggers gt           lt DataTrigger Binding   Binding   Value   x Null   gt               lt Setter Property  Visibility  Value  Visible   gt           lt  DataTrigger gt       lt  Style Triggers gt   lt  Style gt    example of use    lt Grid gt        lt ComboBox x Name  cmb                 ItemsSource   Binding Teams                   SelectedItem   Binding SelectedTeam    gt        lt TextBlock DataContext   Binding ElementName cmb Path SelectedItem                  Text   -- Select Team --                  Style   StaticResource ComboBoxSelectOverlay    gt   lt  Grid gt

User · Answer

I believe a watermark as mentioned in this post would work well in this case  There s a bit of code needed but you can reuse it for any combobox or textbox  and even passwordboxes  so I prefer this way

User · Answer

Set IsEditable  True  on the ComboBox element  This will display the Text property of the ComboBox

User · Answer

I know this is semi old but what about this way    lt DataTemplate x Key  italComboWM  gt       lt TextBlock FontSize  11  FontFamily  Segoe UI  FontStyle  Italic  Text  --Select an item--    gt   lt  DataTemplate gt    lt ComboBox EmptySelectionBoxTemplate   StaticResource italComboWM     gt

User · Answer

The easiest way I ve found to do this is    lt ComboBox Name  MyComboBox   IsEditable  True   IsReadOnly  True   Text  -- Select Team --    gt    You ll obviously need to add your other options  but this is probably the simplest way to do it   There is however one downside to this method which is while the text inside your combo box will not be editable  it is still selectable  However  given the poor quality and complexity of every alternative I ve found to date  this is probably the best option out there

User · Answer

I like Tri Q s answer  but those value converters are a pain to use   PaulB did it with an event handler  but that s also unnecessary   Here s a pure XAML solution    lt ContentControl Content   Binding YourChoices   gt       lt ContentControl ContentTemplate gt           lt DataTemplate gt               lt Grid gt                   lt ComboBox x Name  cb  ItemsSource   Binding    gt                   lt TextBlock x Name  tb  Text  Select Something  IsHitTestVisible  False  Visibility  Hidden   gt               lt  Grid gt               lt DataTemplate Triggers gt                   lt Trigger SourceName  cb  Property  SelectedItem  Value   x Null   gt                       lt Setter TargetName  tb  Property  Visibility  Value  Visible   gt                   lt  Trigger gt               lt  DataTemplate Triggers gt           lt  DataTemplate gt       lt  ContentControl ContentTemplate gt    lt  ContentControl gt

User · Answer

I would recommend the following   Define a behavior  public static class ComboBoxBehaviors       public static readonly DependencyProperty DefaultTextProperty           DependencyProperty RegisterAttached  DefaultText   typeof String   typeof ComboBox   new PropertyMetadata null         public static String GetDefaultText DependencyObject obj                return  String obj GetValue DefaultTextProperty              public static void SetDefaultText DependencyObject obj  String value                var combo    ComboBox obj           RefreshDefaultText combo  value            combo SelectionChanged     sender       gt  RefreshDefaultText  ComboBox sender  GetDefaultText  ComboBox sender             obj SetValue DefaultTextProperty  value              static void RefreshDefaultText ComboBox combo  string text                   if item is selected and DefaultText is set         if  combo SelectedIndex    -1  amp  amp   String IsNullOrEmpty text                            Show DefaultText             var visual   new TextBlock                                 FontStyle   FontStyles Italic                  Text   text                  Foreground   Brushes Gray                             combo Background   new VisualBrush visual                                Stretch   Stretch None                  AlignmentX   AlignmentX Left                  AlignmentY   AlignmentY Center                  Transform   new TranslateTransform 3  0                                   else                          Hide DefaultText             combo Background   null                      User the behavior   lt ComboBox Name  cmb  Margin  72 121 0 0  VerticalAlignment  Top            local ComboBoxBehaviors DefaultText  -- Select Team --   gt

User · Answer

EDIT  Per comments below  this is not a solution  Not sure how I had it working  and can t check that project   It s time to update this answer for the latest XAML    Finding this SO question searching for a solution to this question  I then found that the updated XAML spec has a simple solution   An attribute called  Placeholder  is now available to accomplish this task  It is as simple as this  in Visual Studio 2015     lt ComboBox x Name  Selection  PlaceholderText  Select     gt       lt x String gt Item 1 lt  x String gt       lt x String gt Item 2 lt  x String gt       lt x String gt Item 3 lt  x String gt   lt  ComboBox gt

User · Answer

I did it before binding the combobox with data from database in codebehind like this -  Combobox Items Add  -- Select Team --    Combobox SelectedIndex   0

User · Answer

XAML Code                          ViewModel code      private CategoryModel  SelectedCategory      public CategoryModel SelectedCategory               get   return  SelectedCategory            set                        SelectedCategory   value              OnPropertyChanged  SelectedCategory                         private ObservableCollection lt CategoryModel gt   Categories      public ObservableCollection lt CategoryModel gt  Categories               get   return  Categories            set                        Categories   value               Categories Insert 0  new CategoryModel                                 CategoryId   0                  CategoryName     -- Select Category --                               SelectedCategory    Categories 0               OnPropertyChanged  Categories

User · Answer

No one said a pure xaml solution has to be complicated   Here s a simple one  with 1 data trigger on the text box  Margin and position as desired   lt Grid gt       lt ComboBox x Name  mybox  ItemsSource   Binding    gt       lt TextBlock Text  Select Something  IsHitTestVisible  False  gt              lt TextBlock Style gt                   lt Style TargetType  TextBlock  gt                         lt Setter Property  Visibility  Value  Hidden   gt                         lt Style Triggers gt                               lt DataTrigger Binding   Binding ElementName mybox Path SelectedItem   Value   x Null   gt                                     lt Setter Property  Visibility  Value  Visible   gt                                lt  DataTrigger gt                         lt  Style Triggers gt                   lt  Style gt              lt  TextBlock Style gt        lt  TextBlock gt   lt  Grid gt

[wpf] How to display default text "--Select Team --" in combo box on pageload in WPF?

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