Set focus on TextBox in WPF from view model

Question

I have a TextBox and a Button in my view   Now I am checking a condition upon button click and if the condition turns out to be false  displaying the message to the user  and then I have to set the cursor to the TextBox control   if  companyref    null        var cs   new Lipper Nelson AdminClient Main Views ContactPanels CompanyAssociation          MessageBox Show  Company does not exist     Error   MessageBoxButton OK                      MessageBoxImage Exclamation        cs txtCompanyID Focusable   true       System Windows Input Keyboard Focus cs txtCompanyID       The above code is in the ViewModel   The CompanyAssociation is the view name   But the cursor is not getting set in the TextBox   The xaml is    lt igEditors XamTextEditor Name  txtCompanyID                            KeyDown  xamTextEditorAllowOnlyNumeric KeyDown                           ValueChanged  txtCompanyID ValueChanged                           Text   Binding Company CompanyId                                          Mode TwoWay                                          UpdateSourceTrigger PropertyChanged                            Width   Binding ActualWidth  ElementName border                            Grid Column  1  Grid Row  0                           VerticalAlignment  Top                           HorizontalAlignment  Stretch                           Margin  0 5 0 0                           IsEnabled   Binding Path IsEditable    gt    lt Button Template   StaticResource buttonTemp1           Command   Binding ContactCommand           CommandParameter  searchCompany          Content  Search          Width  80          Grid Row  0  Grid Column  2          VerticalAlignment  Top          Margin  0          HorizontalAlignment  Left          IsEnabled   Binding Path IsEditable    gt

User · Answer

The problem is that once the IsUserNameFocused is set to true, it will never be false. This solves it by handling the GotFocus and LostFocus for the FrameworkElement.

I was having trouble with the source code formatting so here is a link

User · Answer

For Silverlight   using System Windows  using System Windows Controls  using System Windows Interactivity   namespace MyProject Behaviors       public class FocusBehavior   Behavior lt Control gt                protected override void OnAttached                         this AssociatedObject Loaded    AssociatedObject Loaded              base OnAttached                       private void AssociatedObject Loaded object sender  RoutedEventArgs e                        this AssociatedObject Loaded -  AssociatedObject Loaded              if  this HasInitialFocus    this IsFocused                                this GotFocus                                     private void GotFocus                         this AssociatedObject Focus                if  this IsSelectAll                                if  this AssociatedObject is TextBox                                         this AssociatedObject as TextBox  SelectAll                                      else if  this AssociatedObject is PasswordBox                                         this AssociatedObject as PasswordBox  SelectAll                                      else if  this AssociatedObject is RichTextBox                                         this AssociatedObject as RichTextBox  SelectAll                                                       public static readonly DependencyProperty IsFocusedProperty               DependencyProperty Register                   IsFocused                   typeof bool                   typeof FocusBehavior                   new PropertyMetadata false                        d  e    gt                                                 if   bool e NewValue                                                          FocusBehavior d  GotFocus                                                                public bool IsFocused                       get   return  bool GetValue IsFocusedProperty                 set   SetValue IsFocusedProperty  value                        public static readonly DependencyProperty HasInitialFocusProperty               DependencyProperty Register                   HasInitialFocus                   typeof bool                   typeof FocusBehavior                   new PropertyMetadata false  null             public bool HasInitialFocus                       get   return  bool GetValue HasInitialFocusProperty                 set   SetValue HasInitialFocusProperty  value                        public static readonly DependencyProperty IsSelectAllProperty               DependencyProperty Register                   IsSelectAll                   typeof bool                   typeof FocusBehavior                   new PropertyMetadata false  null             public bool IsSelectAll                       get   return  bool GetValue IsSelectAllProperty                 set   SetValue IsSelectAllProperty  value                          LoginViewModel cs       public class LoginModel   ViewModelBase                             private bool  EmailFocus   false          public bool EmailFocus                       get                               return  EmailFocus                            set                               if  value                                         EmailFocus   false                      RaisePropertyChanged  EmailFocus                                       EmailFocus   value                  RaisePropertyChanged  EmailFocus                                              Login xaml   xmlns i  http   schemas microsoft com expression 2010 interactivity  xmlns beh  clr-namespace MyProject Behaviors    lt TextBox Text   Binding Email  Mode TwoWay  UpdateSourceTrigger PropertyChanged   gt       lt i Interaction Behaviors gt           lt beh FocusBehavior IsFocused   Binding EmailFocus   IsSelectAll  True   gt       lt  i Interaction Behaviors gt   lt  TextBox gt    OR   lt TextBox Text   Binding Email  Mode TwoWay  UpdateSourceTrigger PropertyChanged   gt       lt i Interaction Behaviors gt           lt beh FocusBehavior HasInitialFocus  True  IsSelectAll  True   gt       lt  i Interaction Behaviors gt   lt  TextBox gt    To set the focus should just do it in code   EmailFocus   true    Remember that this plugin is part of an html page  so other controls in the page might have the focus  if   Application Current IsRunningOutOfBrowser        System Windows Browser HtmlPage Plugin Focus

User · Answer

I use WPF   Caliburn Micro a found that  dfaivre  has made a general and workable solution  here  http   caliburnmicro codeplex com discussions 222892

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System Windows Forms Application DoEvents    Keyboard Focus tbxLastName

User · Answer

Nobody seems to have included the final step to make it easy to update attributes via binded variables  Here s what I came up with  Let me know if there is a better way of doing this   XAML       lt TextBox x Name  txtLabel        Text   Binding Label         local FocusExtension IsFocused   Binding txtLabel IsFocused  Mode TwoWay           gt        lt Button x Name  butEdit  Content  Edit          Height  40            IsEnabled   Binding butEdit IsEnabled                                   Command   Binding cmdCapsuleEdit Command                                      gt       ViewModel      public class LoginModel   ViewModelBase            public string txtLabel IsFocused   get  set                         public string butEdit IsEnabled   get  set                          public void SetProperty string PropertyName  string value                System Reflection PropertyInfo propertyInfo   this GetType   GetProperty PropertyName           propertyInfo SetValue this  Convert ChangeType value  propertyInfo PropertyType   null           OnPropertyChanged PropertyName                               private void Example function             SetProperty  butEdit IsEnabled    False            SetProperty  txtLabel IsFocused    True

User · Answer

After implementing the accepted answer I did run across an issue that when navigating views with Prism the TextBox would still not get focus   A minor change to the PropertyChanged handler resolved it      private static void OnIsFocusedPropertyChanged DependencyObject d  DependencyPropertyChangedEventArgs e                var uie    UIElement d          if   bool e NewValue                        uie Dispatcher BeginInvoke DispatcherPriority Input  new Action      gt                                uie Focus

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This is an old thread  but there doesn t seem to be an answer with code that addresses the issues with Anavanka s accepted answer  it doesn t work if you set the property in the viewmodel to false  or if you set your property to true  the user manually clicks on something else  and then you set it to true again   I couldn t get Zamotic s solution to work reliably in these cases either   Pulling together some of the discussions above gives me the code below which does address these issues I think   public static class FocusExtension       public static bool GetIsFocused DependencyObject obj                return  bool obj GetValue IsFocusedProperty              public static void SetIsFocused DependencyObject obj  bool value                obj SetValue IsFocusedProperty  value              public static readonly DependencyProperty IsFocusedProperty           DependencyProperty RegisterAttached            IsFocused   typeof bool   typeof FocusExtension            new UIPropertyMetadata false  null  OnCoerceValue         private static object OnCoerceValue DependencyObject d  object baseValue                if   bool baseValue                UIElement d  Focus            else if    UIElement  d  IsFocused              Keyboard ClearFocus            return   bool baseValue             Having said that  this is still complex for something that can be done in one line in codebehind  and CoerceValue isn t really meant to be used in this way  so maybe codebehind is the way to go

User · Answer

Just do this    lt Window x class                     FocusManager FocusedElement   Binding ElementName myTextBox    gt   lt Grid gt   lt TextBox Name  myTextBox   gt

User · Answer

I found Crucial s solution to the IsVisible problem very useful  It didn t completely solve my problem  but some extra code following the same pattern for the IsEnabled pattern did   To the IsFocusedChanged method I added       if   fe IsEnabled                fe IsEnabledChanged    fe IsEnabledChanged          And here s the handler   private static void fe IsEnabledChanged object sender  DependencyPropertyChangedEventArgs e        var fe    FrameworkElement sender      if  fe IsEnabled  amp  amp   bool   FrameworkElement sender  GetValue IsFocusedProperty                 fe IsEnabledChanged -  fe IsEnabledChanged          fe Focus

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In my case  the FocusExtension didn t work until I change the method OnIsFocusedPropertyChanged  The original one was working only in debug when a break point stopped the process  At runtime  the process is too quick and nothing happend  With this little modification and the help of our friend Task  this is working fine in both scenarios   private static void OnIsFocusedPropertyChanged DependencyObject d  DependencyPropertyChangedEventArgs e      var uie    UIElement d    if   bool e NewValue          var action   new Action      gt  uie Dispatcher BeginInvoke  Action       gt  uie Focus           Task Factory StartNew action

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Anvakas brilliant code is for Windows Desktop applications  If you are like me and needed the same solution for Windows Store apps this code might be handy   public static class FocusExtension       public static bool GetIsFocused DependencyObject obj                return  bool obj GetValue IsFocusedProperty               public static void SetIsFocused DependencyObject obj  bool value                obj SetValue IsFocusedProperty  value               public static readonly DependencyProperty IsFocusedProperty           DependencyProperty RegisterAttached            IsFocused   typeof bool   typeof FocusExtension            new PropertyMetadata false  OnIsFocusedPropertyChanged          private static void OnIsFocusedPropertyChanged DependencyObject d          DependencyPropertyChangedEventArgs e                if   bool e NewValue                        var uie   d as Windows UI Xaml Controls Control               if  uie    null                                 uie Focus FocusState Programmatic

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I have found solution by editing code as per following  There is no need to set Binding property first False then True   public static class FocusExtension        public static bool GetIsFocused DependencyObject obj                return  bool obj GetValue IsFocusedProperty               public static void SetIsFocused DependencyObject obj  bool value                obj SetValue IsFocusedProperty  value               public static readonly DependencyProperty IsFocusedProperty           DependencyProperty RegisterAttached            IsFocused   typeof bool   typeof FocusExtension            new UIPropertyMetadata false  OnIsFocusedPropertyChanged          private static void OnIsFocusedPropertyChanged DependencyObject d  DependencyPropertyChangedEventArgs e                if  d    null  amp  amp  d is Control                        var  Control   d as Control              if   bool e NewValue                                   To set false value to get focus on control  if we don t set value to False then we have to set all binding                   property to first False then True to set focus on control                  OnLostFocus  Control  null                    Control Focus       Don t care about false values                                     private static void OnLostFocus object sender  RoutedEventArgs e                if  sender    null  amp  amp  sender is Control                         sender as Control  SetValue IsFocusedProperty  false

User · Answer

public class DummyViewModel   ViewModelBase               private bool isfocused  false          public bool IsFocused                       get                               return isfocused                            set                               isfocused  value                  OnPropertyChanged  IsFocused

User · Answer

Let me answer to your question in three parts     I m wondering what is  cs txtCompanyID  in your example   Is it a TextBox control  If yes  then you are on a wrong way  Generally speaking it s not a good idea to have any reference to UI in your ViewModel  You can ask  Why   but this is another question to post on Stackoverflow     The best way to track down issues with Focus is    debugging  Net source code  No kidding  It saved me a lot of time many times  To enable  net source code debugging refer to Shawn Bruke s blog  Finally  general approach that I use to set focus from ViewModel is Attached Properties  I wrote very simple attached property  which can be set on any UIElement  And it can be bound to ViewModel s property  IsFocused  for example  Here it is   public static class FocusExtension       public static bool GetIsFocused DependencyObject obj                return  bool  obj GetValue IsFocusedProperty              public static void SetIsFocused DependencyObject obj  bool value                obj SetValue IsFocusedProperty  value              public static readonly DependencyProperty IsFocusedProperty           DependencyProperty RegisterAttached               IsFocused   typeof  bool   typeof  FocusExtension               new UIPropertyMetadata false  OnIsFocusedPropertyChanged         private static void OnIsFocusedPropertyChanged          DependencyObject d           DependencyPropertyChangedEventArgs e                var uie    UIElement  d          if   bool  e NewValue                        uie Focus       Don t care about false values                      Now in your View  in XAML  you can bind this property to your ViewModel    lt TextBox local FocusExtension IsFocused   Binding IsUserNameFocused     gt     Hope this helps     If it doesn t refer to the answer  2    Cheers

User · Answer

None of these worked for me exactly  but for the benefit of others  this is what I ended up writing based on some of the code already provided here   Usage would be as follows    lt TextBox     h FocusBehavior IsFocused  True   gt    And the implementation would be as follows        lt summary gt      Behavior allowing to put focus on element from the view model in a MVVM implementation       lt  summary gt  public static class FocusBehavior        region Dependency Properties          lt summary gt           lt c gt IsFocused lt  c gt  dependency property           lt  summary gt      public static readonly DependencyProperty IsFocusedProperty           DependencyProperty RegisterAttached  IsFocused   typeof bool                typeof FocusBehavior   new FrameworkPropertyMetadata IsFocusedChanged             lt summary gt          Gets the  lt c gt IsFocused lt  c gt  property value           lt  summary gt           lt param name  element  gt The element  lt  param gt           lt returns gt Value of the  lt c gt IsFocused lt  c gt  property or  lt c gt null lt  c gt  if not set  lt  returns gt      public static bool  GetIsFocused DependencyObject element                if  element    null                        throw new ArgumentNullException  element                      return  bool  element GetValue IsFocusedProperty                  lt summary gt          Sets the  lt c gt IsFocused lt  c gt  property value           lt  summary gt           lt param name  element  gt The element  lt  param gt           lt param name  value  gt The value  lt  param gt      public static void SetIsFocused DependencyObject element  bool  value                if  element    null                        throw new ArgumentNullException  element                      element SetValue IsFocusedProperty  value              endregion Dependency Properties       region Event Handlers          lt summary gt          Determines whether the value of the dependency property  lt c gt IsFocused lt  c gt  has change           lt  summary gt           lt param name  d  gt The dependency object  lt  param gt           lt param name  e  gt The  lt see cref  System Windows DependencyPropertyChangedEventArgs   gt  instance containing the event data  lt  param gt      private static void IsFocusedChanged DependencyObject d  DependencyPropertyChangedEventArgs e                   Ensure it is a FrameworkElement instance          var fe   d as FrameworkElement          if  fe    null  amp  amp  e OldValue    null  amp  amp  e NewValue    null  amp  amp   bool e NewValue                           Attach to the Loaded event to set the focus there  If we do it here it will                be overridden by the view rendering the framework element              fe Loaded    FrameworkElementLoaded                           lt summary gt          Sets the focus when the framework element is loaded and ready to receive input           lt  summary gt           lt param name  sender  gt The sender  lt  param gt           lt param name  e  gt The  lt see cref  System Windows RoutedEventArgs   gt  instance containing the event data  lt  param gt      private static void FrameworkElementLoaded object sender  RoutedEventArgs e                   Ensure it is a FrameworkElement instance          var fe   sender as FrameworkElement          if  fe    null                           Remove the event handler registration              fe Loaded -  FrameworkElementLoaded                 Set the focus to the given framework element              fe Focus                   Determine if it is a text box like element              var tb   fe as TextBoxBase              if  tb    null                                   Select all text to be ready for replacement                  tb SelectAll                                       endregion Event Handlers

User · Answer

First off i would like to thank Avanka for helping me solve my focus problem  There is however a bug in the code he posted  namely in the line      if  e OldValue    null   The problem I had was that if you first click in your view and focus the control  e oldValue is no longer null  Then when you set the variable to focus the control for the first time  this results in the lostfocus and gotfocus handlers not being set  My solution to this was as follows   public static class ExtensionFocus           static ExtensionFocus                     BoundElements   new List lt string gt                    public static readonly DependencyProperty IsFocusedProperty           DependencyProperty RegisterAttached  IsFocused   typeof bool            typeof ExtensionFocus   new FrameworkPropertyMetadata false  IsFocusedChanged         private static List lt string gt  BoundElements       public static bool  GetIsFocused DependencyObject element                    if  element    null                            throw new ArgumentNullException  ExtensionFocus GetIsFocused called with null element                          return  bool  element GetValue IsFocusedProperty                  public static void SetIsFocused DependencyObject element  bool  value                    if  element    null                            throw new ArgumentNullException  ExtensionFocus SetIsFocused called with null element                          element SetValue IsFocusedProperty  value                  private static void IsFocusedChanged DependencyObject d  DependencyPropertyChangedEventArgs e                    var fe    FrameworkElement d              OLD LINE             if  e OldValue    null             TWO NEW LINES          if  BoundElements Contains fe Name     false                            BoundElements Add fe Name               fe LostFocus    OnLostFocus              fe GotFocus    OnGotFocus                                     if   fe IsVisible                            fe IsVisibleChanged    new DependencyPropertyChangedEventHandler fe IsVisibleChanged                          if   bool e NewValue                            fe Focus                                              private static void fe IsVisibleChanged object sender  DependencyPropertyChangedEventArgs e                    var fe    FrameworkElement sender           if  fe IsVisible  amp  amp   bool   FrameworkElement sender  GetValue IsFocusedProperty                             fe IsVisibleChanged -  fe IsVisibleChanged              fe Focus                                 private static void OnLostFocus object sender  RoutedEventArgs e                    if  sender    null  amp  amp  sender is Control s                            s SetValue IsFocusedProperty  false                                private static void OnGotFocus object sender  RoutedEventArgs e                    if  sender    null  amp  amp  sender is Control s                            s SetValue IsFocusedProperty  true

User · Answer

I think the best way is to keep the MVVM principle clean  so basically you must use the Messenger Class provided with the MVVM Light and here is how to use it   in your viewmodel exampleViewModel cs  write the following    Messenger Default Send lt string gt   focus    DoFocus      now in your View cs not the XAML the view xaml cs  write the following in the constructor   public MyView                         InitializeComponent                 Messenger Default Register lt string gt  this   DoFocus   doFocus                     public void doFocus string msg                        if  msg     focus                   this txtcode Focus                that method owrks just fine and with less code and maintaining MVVM standards

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I know this question has been answered a thousand times over by now  but I made some edits to Anvaka s contribution that I think will help others that had similar issues that I had  Firstly  I changed the above Attached Property like so  public static class FocusExtension       public static readonly DependencyProperty IsFocusedProperty            DependencyProperty RegisterAttached  quot IsFocused quot   typeof bool    typeof FocusExtension   new FrameworkPropertyMetadata IsFocusedChanged  BindsTwoWayByDefault   true         public static bool  GetIsFocused DependencyObject element                if  element    null                        throw new ArgumentNullException  quot element quot                       return  bool  element GetValue IsFocusedProperty              public static void SetIsFocused DependencyObject element  bool  value                if  element    null                        throw new ArgumentNullException  quot element quot                       element SetValue IsFocusedProperty  value              private static void IsFocusedChanged DependencyObject d  DependencyPropertyChangedEventArgs e                var fe    FrameworkElement d           if  e OldValue    null                        fe GotFocus    FrameworkElement GotFocus              fe LostFocus    FrameworkElement LostFocus                     if   fe IsVisible                        fe IsVisibleChanged    new DependencyPropertyChangedEventHandler fe IsVisibleChanged                      if  e NewValue    null  amp  amp   bool e NewValue                        fe Focus                         private static void fe IsVisibleChanged object sender  DependencyPropertyChangedEventArgs e                var fe    FrameworkElement sender          if  fe IsVisible  amp  amp   bool fe GetValue IsFocusedProperty                         fe IsVisibleChanged -  fe IsVisibleChanged              fe Focus                         private static void FrameworkElement GotFocus object sender  RoutedEventArgs e                  FrameworkElement sender  SetValue IsFocusedProperty  true              private static void FrameworkElement LostFocus object sender  RoutedEventArgs e                  FrameworkElement sender  SetValue IsFocusedProperty  false            My reason for adding the visibility references were tabs  Apparently if you used the attached property on any other tab outside of the initially visible tab  the attached property didn t work until you manually focused the control  The other obstacle was creating a more elegant way of resetting the underlying property to false when it lost focus  That s where the lost focus events came in   lt TextBox                 Text  quot  Binding Description  quot      FocusExtension IsFocused  quot  Binding IsFocused  quot   gt   If there s a better way to handle the visibility issue  please let me know  Note  Thanks to Apfelkuacha for the suggestion of putting the BindsTwoWayByDefault in the DependencyProperty  I had done that long ago in my own code  but never updated this post  The Mode TwoWay is no longer necessary in the WPF code due to this change

User · Answer

An alternative approach based on  Sheridan answer here    lt TextBox Text   Binding SomeText  Mode TwoWay  UpdateSourceTrigger PropertyChanged   gt           lt TextBox Style gt               lt Style gt                   lt Style Triggers gt                       lt DataTrigger Binding   Binding SomeTextIsFocused  Mode TwoWay  UpdateSourceTrigger PropertyChanged   Value  True  gt                           lt Setter Property  FocusManager FocusedElement  Value   Binding RelativeSource  RelativeSource Self      gt                       lt  DataTrigger gt                   lt  Style Triggers gt               lt  Style gt           lt  TextBox Style gt       lt  TextBox gt    In your view model set up your binding in the usual way and then set the SomeTextIsFocused to true to set the focus on your text box

User · Answer

You could use the ViewCommand design pattern  It describes a method for the MVVM design pattern to control a View from a ViewModel with commands   I ve implemented it based on King A Majid s suggestion to use the MVVM Light Messenger class  The ViewCommandManager class handles invoking commands in connected views  It s basically the other direction of regular Commands  for these cases when a ViewModel needs to do some action in its View  It uses reflection like data-bound commands and WeakReferences to avoid memory leaks   http   dev unclassified de source viewcommand  also published on CodeProject

User · Answer

For those trying to use Anvaka s solution above  I was having issues with the binding only working the first time  as lostfocus would not update the property to false  You can manually set the property to false and then true every time  but a better solution could be to do something like this in your property   bool  isFocused   false      public bool IsFocused                get   return  isFocused             set                        isFocused   false               isFocused   value              base OnPropertyChanged  IsFocused                       This way you only ever need to set it to true  and it will get focus

[c#] Set focus on TextBox in WPF from view model

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