Close Window from ViewModel

Question

Im creating a Login using a window control to allow a user to login into a WPF application that I am creating    So far  I have created a method that checks whether the user has entered in the correct credentials for the username and password in a textbox on the login screen  binding two properties    I have achieved this by creating a bool method  like so   public bool CheckLogin         var user   context Users Where i   gt  i Username    this Username  SingleOrDefault         if  user    null                MessageBox Show  Unable to Login  incorrect credentials             return false            else if  this Username    user Username    this Password ToString      user Password                MessageBox Show  Welcome     user Username      you have successfully logged in              return true            else               MessageBox Show  Unable to Login  incorrect credentials             return false           public ICommand ShowLoginCommand       get               if  this showLoginCommand    null                        this showLoginCommand   new RelayCommand this LoginExecute  null                     return this showLoginCommand           private void LoginExecute         this CheckLogin         I also have a command that I bind to my button within the xaml like so    lt Button Name  btnLogin  IsDefault  True  Content  Login  Command   Binding ShowLoginCommand     gt    When I enter in the username and password it executes the appropriated code  whether it being right  or wrong  But how can I close this window from the ViewModel when both username and password are correct   I have previously tried using a dialog modal but it didn t quite work out  Furthermore  within my app xaml  I have done something like the following  which loads the login page first  then once true  loads the actual application   private void ApplicationStart object sender  StartupEventArgs e        Current ShutdownMode   ShutdownMode OnExplicitShutdown       var dialog   new UserView         if  dialog ShowDialog      true                var mainWindow   new MainWindow            Current ShutdownMode   ShutdownMode OnMainWindowClose          Current MainWindow   mainWindow          mainWindow Show              else               MessageBox Show  Unable to load application     Error   MessageBoxButton OK           Current Shutdown -1             Question  How can I close the Login Window control from the ViewModel   Thanks in advance

User · Answer

You can close the current window just by using the following code   Application Current Windows 0  Close

User · Answer

You can create new Event handler in the ViewModel like this   public event EventHandler RequestClose       protected void OnRequestClose                 if  RequestClose    null              RequestClose this  EventArgs Empty           Then Define RelayCommand for ExitCommand   private RelayCommand  CloseCommand      public ICommand CloseCommand               get                       if this  CloseCommand  null                  this  CloseCommand new RelayCommand CloseClick               return this  CloseCommand                       private void CloseClick object obj                OnRequestClose            Then In XAML file set    lt Button Command   Binding CloseCommand     gt    Set the DataContext in the xaml cs File and Subscribe to the event we created   public partial class MainWindow   Window       private ViewModel mainViewModel   null      public MainWindow                 InitializeComponent            mainViewModel   new ViewModel            this DataContext   mainViewModel          mainViewModel RequestClose    delegate object sender  EventArgs args    this Close

User · Answer

it may be late  but here is my answer  foreach  Window item in Application Current Windows        if  item DataContext    this  item Close

User · Answer

You can pass the window to your ViewModel using the CommandParameter  See my Example below   I ve implemented an CloseWindow Method which takes a Windows as parameter and closes it  The window is passed to the ViewModel via CommandParameter  Note that you need to define an x Name for the window which should be close  In my XAML Window i call this method via Command and pass the window itself as a parameter to the ViewModel using CommandParameter   Command   Binding CloseWindowCommand  Mode OneWay    CommandParameter   Binding ElementName TestWindow     ViewModel  public RelayCommand lt Window gt  CloseWindowCommand   get  private set     public MainViewModel         this CloseWindowCommand   new RelayCommand lt Window gt  this CloseWindow      private void CloseWindow Window window        if  window    null               window Close              View   lt Window x Class  ClientLibTestTool ErrorView          x Name  TestWindow          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml          xmlns localization  clr-namespace ClientLibTestTool ViewLanguages          DataContext   Binding Main  Source  StaticResource Locator            Title   x Static localization localization HeaderErrorView           Height  600  Width  800          ResizeMode  NoResize          WindowStartupLocation  CenterScreen  gt       lt Grid gt            lt Button Content   x Static localization localization ButtonClose                    Height  30                   Width  100                   Margin  0 0 10 10                   IsCancel  True                   VerticalAlignment  Bottom                   HorizontalAlignment  Right                   Command   Binding CloseWindowCommand  Mode OneWay                    CommandParameter   Binding ElementName TestWindow    gt       lt  Grid gt   lt  Window gt    Note that i m using the MVVM light framework  but the principal applies to every wpf application   This solution violates of the MVVM pattern  because the view-model shouldn t know anything about the UI Implementation  If you want to strictly follow the MVVM programming paradigm you have to abstract the type of the view with an interface   MVVM conform solution  Former EDIT2   the user Crono mentions a valid point in the comment section      Passing the Window object to the view model breaks the MVVM pattern   IMHO  because it forces your vm to know what it s being viewed in    You can fix this by introducing an interface containing a close method    Interface   public interface ICloseable       void Close        Your refactored ViewModel will look like this   ViewModel  public RelayCommand lt ICloseable gt  CloseWindowCommand   get  private set     public MainViewModel         this CloseWindowCommand   new RelayCommand lt IClosable gt  this CloseWindow      private void CloseWindow ICloseable window        if  window    null                window Close              You have to reference and implement the ICloseable interface in your view  View  Code behind   public partial class MainWindow   Window  ICloseable       public MainWindow                 InitializeComponent              Answer to the original question   former EDIT1   Your Login Button  Added CommandParameter     lt Button Name  btnLogin  IsDefault  True  Content  Login  Command   Binding ShowLoginCommand   CommandParameter   Binding ElementName LoginWindow    gt    Your code    public RelayCommand lt Window gt  CloseWindowCommand   get  private set       the  lt Window gt  is important for your solution    public MainViewModel              initialize the CloseWindowCommand  Again  mind the  lt Window gt         you don t have to do this in your constructor but it is good practice  thought      this CloseWindowCommand   new RelayCommand lt Window gt  this CloseWindow        public bool CheckLogin Window loginWindow    Added loginWindow Parameter        var user   context Users Where i   gt  i Username    this Username  SingleOrDefault         if  user    null                MessageBox Show  Unable to Login  incorrect credentials             return false            else if  this Username    user Username    this Password ToString      user Password                MessageBox Show  Welcome    user Username      you have successfully logged in             this CloseWindow loginWindow     Added call to CloseWindow Method         return true            else               MessageBox Show  Unable to Login  incorrect credentials             return false               Added CloseWindow Method  private void CloseWindow Window window          if  window    null                  window Close

User · Answer

This is a way I did it pretty simply   YourWindow xaml cs    In your constructor public YourWindow         InitializeComponent        DataContext   new YourWindowViewModel this       YourWindowViewModel cs  private YourWindow window   so we can kill the window    In your constructor public YourWindowViewModel YourWindow window        this window   window       to close the window public void CloseWindow         window Close        I don t see anything wrong with the answer you chose  I just thought this might be a more simple way to do it

User · Answer

Well here is something I used in several projects  It may look like a hack  but it works fine   public class AttachedProperties   DependencyObject   adds a bindable DialogResult to window       public static readonly DependencyProperty DialogResultProperty            DependencyProperty RegisterAttached  DialogResult   typeof bool    typeof AttachedProperties            new PropertyMetaData default bool    OnDialogResultChanged         public bool  DialogResult               get   return  bool  GetValue DialogResultProperty             set   SetValue DialogResultProperty  value                private static void OnDialogResultChanged DependencyObject d  DependencyPropertyChangedEventArgs e                var window   d as Window          if  window    null              return           window DialogResult    bool  e NewValue            Now you can bind DialogResult to a VM and set its value of a property  The Window will close  when the value is set    lt  -- Assuming that the VM is bound to the DataContext and the bound VM has a property DialogResult -- gt   lt Window someNs AttachedProperties DialogResult  Binding DialogResult    gt    This is an abstract of what s running in our production environment   lt Window x Class  AC Frontend Controls DialogControl Dialog          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml          xmlns DialogControl  clr-namespace AC Frontend Controls DialogControl           xmlns hlp  clr-namespace AC Frontend Helper          MinHeight  150  MinWidth  300  ResizeMode  NoResize  SizeToContent  WidthAndHeight          WindowStartupLocation  CenterScreen  Title   Binding Title           hlp AttachedProperties DialogResult   Binding DialogResult   WindowStyle  ToolWindow  ShowInTaskbar  True          Language   Binding UiCulture  Source  StaticResource Strings    gt           lt  -- A lot more stuff here -- gt   lt  Window gt    As you can see  I m declaring the namespace xmlns hlp  clr-namespace AC Frontend Helper  first and afterwards the binding hlp AttachedProperties DialogResult   Binding DialogResult      The AttachedProperty looks like this  It s not the same I posted yesterday  but IMHO it shouldn t have any effect   public class AttachedProperties        region DialogResult      public static readonly DependencyProperty DialogResultProperty           DependencyProperty RegisterAttached  DialogResult   typeof  bool    typeof  AttachedProperties   new PropertyMetadata default bool    OnDialogResultChanged         private static void OnDialogResultChanged DependencyObject d  DependencyPropertyChangedEventArgs e                var wnd   d as Window          if  wnd    null              return           wnd DialogResult    bool   e NewValue             public static bool  GetDialogResult DependencyObject dp                if  dp    null  throw new ArgumentNullException  dp             return  bool  dp GetValue DialogResultProperty              public static void SetDialogResult DependencyObject dp  object value                if  dp    null  throw new ArgumentNullException  dp             dp SetValue DialogResultProperty  value               endregion

User · Answer

You may treat window as a service  eg  UI service  and pass itself to viewmodel via an interface  as such   public interface IMainWindowAccess       void Close bool result      public class MainWindow   IMainWindowAccess                    public void Close bool result                DialogResult   result          Close             public class MainWindowViewModel       private IMainWindowAccess access       public MainWindowViewModel IMainWindowAccess access                this access   access             public void DoClose                 access Close true             This solution have most upsides of passing the view itself to viewmodel without having downside of breaking MVVM  because though physically view is passed to viewmodel  the latter still don t know about the former  it sees only some IMainWindowAccess  So for instance if we wanted to migrate this solution to other platform  it would be only a matter of implementing IMainWindowAccess properly for  say  an Activity   I m posting the solution here to propose a different approach than events  though it s actually very similar   because it seems a little bit simpler than events to implement  attaching detaching etc    but still aligns nicely with MVVM pattern

User · Answer

You can use Messenger from MVVMLight toolkit   in your ViewModel send a message like this  Messenger Default Send new NotificationMessage  Close       then in your windows code behind  after InitializeComponent  register for that message like this     Messenger Default Register lt NotificationMessage gt  this  m  gt       if m Notification     Close                  this Close                   you can find more about MVVMLight toolkit here  MVVMLight toolkit on Codeplex  Notice that there is not a  no code-behind at all rule  in MVVM and you can do registering for messages in a view code-behind

User · Answer

System Environment Exit 0   in view model would work

User · Answer

My proffered way is Declare event in ViewModel and use blend InvokeMethodAction as below   Sample ViewModel  public class MainWindowViewModel   BindableBase  ICloseable       public DelegateCommand SomeCommand   get  private set         region ICloseable Implementation     public event EventHandler CloseRequested               public void RaiseCloseNotification                 var handler   CloseRequested          if  handler    null                        handler Invoke this  EventArgs Empty                        endregion      public MainWindowViewModel                 SomeCommand   new DelegateCommand      gt                          when you decide to close window             RaiseCloseNotification                          I Closeable interface is as below but don t require to perform this action  ICloseable will help in creating generic view service  so if you construct view and ViewModel by dependency injection then what you can do is   internal interface ICloseable       event EventHandler CloseRequested      Use of ICloseable  var viewModel   new MainWindowViewModel               As service is generic and don t know whether it can request close event         var window   new Window     Content   new MainView              var closeable   viewModel as ICloseable          if  closeable    null                        closeable CloseRequested     s  e    gt  window Close                And Below is Xaml  You can use this xaml even if you don t implement interface  it will only need your view model to raise CloseRquested     lt Window xmlns  http   schemas microsoft com winfx 2006 xaml presentation  xmlns x  http   schemas microsoft com winfx 2006 xaml  xmlns d  http   schemas microsoft com expression blend 2008  xmlns mc  http   schemas openxmlformats org markup-compatibility 2006  xmlns local  clr-namespace WPFRx  xmlns i  http   schemas microsoft com expression 2010 interactivity   xmlns ei  http   schemas microsoft com expression 2010 interactions   xmlns ViewModels  clr-namespace WPFRx ViewModels  x Name  window  x Class  WPFRx MainWindow      mc Ignorable  d      Title  MainWindow  Height  350  Width  525   d DataContext   d DesignInstance  x Type ViewModels MainWindowViewModel    gt    lt i Interaction Triggers gt       lt i EventTrigger SourceObject   Binding Mode OneWay   EventName  CloseRequested   gt           lt ei CallMethodAction TargetObject   Binding ElementName window   MethodName  Close   gt       lt  i EventTrigger gt   lt  i Interaction Triggers gt    lt Grid gt       lt Button Content  Some Content  Command   Binding SomeCommand   Width  100  Height  25   gt   lt  Grid gt

User · Answer

I know this is an old post  probably no one would scroll this far  I know I didn t  So  after hours of trying different stuff  I found this blog and dude killed it  Simplest way to do this  tried it and it works like a charm   Blog  In the ViewModel        public bool CanClose   get  set     private RelayCommand closeCommand  public ICommand CloseCommand       get               if closeCommand    null                        closeCommand   new RelayCommand param   gt  Close    param   gt  CanClose                      public void Close         this Close             add an Action property to the ViewModel  but define it from the View   s code-behind file  This will let us dynamically define a reference on the ViewModel that points to the View   On the ViewModel  we   ll simply add   public Action CloseAction   get  set      And on the View  we   ll define it as such   public View         InitializeComponent      this draws the View     ViewModel vm   new ViewModel       this creates an instance of the ViewModel     this DataContext   vm     this sets the newly created ViewModel as the DataContext for the View     if   vm CloseAction    null           vm CloseAction   new Action      gt  this Close

User · Answer

It s simple  You can create your own ViewModel class for Login - LoginViewModel  You can create view var dialog   new  UserView    inside your LoginViewModel   And you can set-up Command LoginCommand into button    lt Button Name  btnLogin  IsDefault  True  Content  Login  Command   Binding LoginCommand     gt    and    lt Button Name  btnCancel  IsDefault  True  Content  Login  Command   Binding CancelCommand     gt    ViewModel class   public class LoginViewModel       Window dialog      public bool ShowLogin                dialog   new UserView           dialog DataContext   this     set up ViewModel into View        if  dialog ShowDialog      true                    return true                   return false             ICommand  loginCommand     public ICommand LoginCommand               get                       if   loginCommand    null                   loginCommand   new RelayCommand param   gt  this Login                  return  loginCommand                       public void CloseLoginView                     if  dialog    null            dialog Close                  public void Login                 if CheckLogin    true                        CloseLoginView                               else                        write error message                      public bool CheckLogin                      check login code       return true

User · Answer

How about this    ViewModel   class ViewModel       public Action CloseAction   get  set        private void Stuff                   Do Stuff        CloseAction       closes the window           In your ViewModel use CloseAction   to close the window just like in the example above   View   public View         InitializeComponent        ViewModel vm   new ViewModel        this creates an instance of the ViewModel     this DataContext   vm     this sets the newly created ViewModel as the DataContext for the View     if  vm CloseAction    null          vm CloseAction   new Action      gt  this Close

User · Answer

Staying MVVM  I think using either Behaviors from the Blend SDK  System Windows Interactivity  or a custom interaction request from Prism could work really well for this sort of situation   If going the Behavior route  here s the general idea   public class CloseWindowBehavior   Behavior lt Window gt        public bool CloseTrigger               get   return  bool GetValue CloseTriggerProperty             set   SetValue CloseTriggerProperty  value                public static readonly DependencyProperty CloseTriggerProperty           DependencyProperty Register  CloseTrigger   typeof bool   typeof CloseWindowBehavior   new PropertyMetadata false  OnCloseTriggerChanged         private static void OnCloseTriggerChanged DependencyObject d  DependencyPropertyChangedEventArgs e                var behavior   d as CloseWindowBehavior           if  behavior    null                        behavior OnCloseTriggerChanged                         private void OnCloseTriggerChanged                    when closetrigger is true  close the window         if  this CloseTrigger                        this AssociatedObject Close                        Then in your window  you would just bind the CloseTrigger to a boolean value that would be set when you wanted the window to close    lt Window x Class  TestApp MainWindow          xmlns  http   schemas microsoft com winfx 2006 xaml presentation          xmlns x  http   schemas microsoft com winfx 2006 xaml          xmlns i  clr-namespace System Windows Interactivity assembly System Windows Interactivity          xmlns local  clr-namespace TestApp          Title  MainWindow  Height  350  Width  525  gt       lt i Interaction Behaviors gt           lt local CloseWindowBehavior CloseTrigger   Binding CloseTrigger     gt       lt  i Interaction Behaviors gt        lt Grid gt        lt  Grid gt   lt  Window gt    Finally  your DataContext ViewModel would have a property that you d set when you wanted the window to close like this   public class MainWindowViewModel   INotifyPropertyChanged       private bool closeTrigger            lt summary gt          Gets or Sets if the main window should be closed          lt  summary gt      public bool CloseTrigger               get   return this closeTrigger            set                       this closeTrigger   value              RaisePropertyChanged nameof CloseTrigger                         public MainWindowViewModel                    just setting for example  close the window         CloseTrigger   true             protected void RaisePropertyChanged string propertyName                if  PropertyChanged    null                        PropertyChanged this  new PropertyChangedEventArgs propertyName                         public event PropertyChangedEventHandler PropertyChanged       set your Window DataContext   new MainWindowViewModel

User · Answer

Here is a simple example using the MVVM Light Messenger instead of an event   The view model sends a close message when a button is clicked       public MainViewModel                 QuitCommand   new RelayCommand ExecuteQuitCommand              public RelayCommand QuitCommand   get  private set         private void ExecuteQuitCommand                  Messenger Default Send lt CloseMessage gt  new CloseMessage             Then it is received in the code behind of the window       public Main                    InitializeComponent            Messenger Default Register lt CloseMessage gt  this  HandleCloseMessage              private void HandleCloseMessage CloseMessage closeMessage                Close

User · Answer

I usually put an event on the view model when I need to do this and then hook it up to the Window Close   when binding the view model to the window  public class LoginViewModel       public event EventHandler OnRequestClose       private void Login                    Login logic here         OnRequestClose this  new EventArgs               And when creating the login window  var vm   new LoginViewModel    var loginWindow   new LoginWindow       DataContext   vm    vm OnRequestClose     s  e    gt  loginWindow Close     loginWindow ShowDialog

User · Answer

Easy way  public interface IRequireViewIdentification       Guid ViewID   get        Implement to ViewModel  public class MyViewVM   IRequireViewIdentification       private Guid  viewId       public Guid ViewID               get   return  viewId               public MyViewVM                  viewId   Guid NewGuid              Add general window manager helper  public static class WindowManager       public static void CloseWindow Guid id                foreach  Window window in Application Current Windows                        var w id   window DataContext as IRequireViewIdentification              if  w id    null  amp  amp  w id ViewID Equals id                                 window Close                                      And close it like this in viewmodel  WindowManager CloseWindow ViewID

[c#] Close Window from ViewModel

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