Problem with Dependency Property and PropertyChangedCallback in WPF
1
In my CustomControl, I have the View dependency property. The outer control that uses this control sets this property via a view model. When it is set, a Refresh method is trigerred and the View is rendered!
Everything is fine so far! But what if I also want it to Refresh when a property of the View is changed.
Maybe I am not doing it the standard way? Should I define a public Refresh() method on the control and call it from outside? How can I use commanding?
public static readonly DependencyProperty ViewProperty =
DependencyProperty.Register(
"View", typeof(View),
typeof(CustomControl), new PropertyMetadata(Refresh)
);
public View View
get => (View)GetValue(ViewProperty);
set => SetValue(ViewProperty, value);
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
//
MessageBox.Show("Refreshed!");
public sealed class View : INotifyPropertyChanged
private bool m_isDirty;
public bool IsDirty
get => m_isDirty;
set
m_isDirty = value;
OnPropertyChanged();
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged([CallerMemberName] string propertyName = null)
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
c# wpf mvvm dependency-properties inotifypropertychanged
edited Nov 15 '18 at 6:16
Blacktempel
2,88231739
asked Nov 14 '18 at 13:13
VahidVahid
1,89453684
add a comment |
1
In my CustomControl, I have the View dependency property. The outer control that uses this control sets this property via a view model. When it is set, a Refresh method is trigerred and the View is rendered!
Everything is fine so far! But what if I also want it to Refresh when a property of the View is changed.
Maybe I am not doing it the standard way? Should I define a public Refresh() method on the control and call it from outside? How can I use commanding?
public static readonly DependencyProperty ViewProperty =
DependencyProperty.Register(
"View", typeof(View),
typeof(CustomControl), new PropertyMetadata(Refresh)
);
public View View
get => (View)GetValue(ViewProperty);
set => SetValue(ViewProperty, value);
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
//
MessageBox.Show("Refreshed!");
public sealed class View : INotifyPropertyChanged
private bool m_isDirty;
public bool IsDirty
get => m_isDirty;
set
m_isDirty = value;
OnPropertyChanged();
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged([CallerMemberName] string propertyName = null)
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
c# wpf mvvm dependency-properties inotifypropertychanged
edited Nov 15 '18 at 6:16
Blacktempel
2,88231739
asked Nov 14 '18 at 13:13
VahidVahid
1,89453684
add a comment |
1
1
1
In my CustomControl, I have the View dependency property. The outer control that uses this control sets this property via a view model. When it is set, a Refresh method is trigerred and the View is rendered!
Everything is fine so far! But what if I also want it to Refresh when a property of the View is changed.
Maybe I am not doing it the standard way? Should I define a public Refresh() method on the control and call it from outside? How can I use commanding?
public static readonly DependencyProperty ViewProperty =
DependencyProperty.Register(
"View", typeof(View),
typeof(CustomControl), new PropertyMetadata(Refresh)
);
public View View
get => (View)GetValue(ViewProperty);
set => SetValue(ViewProperty, value);
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
//
MessageBox.Show("Refreshed!");
public sealed class View : INotifyPropertyChanged
private bool m_isDirty;
public bool IsDirty
get => m_isDirty;
set
m_isDirty = value;
OnPropertyChanged();
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged([CallerMemberName] string propertyName = null)
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
c# wpf mvvm dependency-properties inotifypropertychanged
edited Nov 15 '18 at 6:16
Blacktempel
2,88231739
asked Nov 14 '18 at 13:13
VahidVahid
1,89453684
In my CustomControl, I have the View dependency property. The outer control that uses this control sets this property via a view model. When it is set, a Refresh method is trigerred and the View is rendered!
Everything is fine so far! But what if I also want it to Refresh when a property of the View is changed.
Maybe I am not doing it the standard way? Should I define a public Refresh() method on the control and call it from outside? How can I use commanding?
public static readonly DependencyProperty ViewProperty =
DependencyProperty.Register(
"View", typeof(View),
typeof(CustomControl), new PropertyMetadata(Refresh)
);
public View View
get => (View)GetValue(ViewProperty);
set => SetValue(ViewProperty, value);
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
//
MessageBox.Show("Refreshed!");
public sealed class View : INotifyPropertyChanged
private bool m_isDirty;
public bool IsDirty
get => m_isDirty;
set
m_isDirty = value;
OnPropertyChanged();
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged([CallerMemberName] string propertyName = null)
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
c# wpf mvvm dependency-properties inotifypropertychanged
c# wpf mvvm dependency-properties inotifypropertychanged
edited Nov 15 '18 at 6:16
Blacktempel
2,88231739
asked Nov 14 '18 at 13:13
VahidVahid
1,89453684
edited Nov 15 '18 at 6:16
Blacktempel
2,88231739
asked Nov 14 '18 at 13:13
VahidVahid
1,89453684
edited Nov 15 '18 at 6:16
Blacktempel
2,88231739
edited Nov 15 '18 at 6:16
Blacktempel
2,88231739
edited Nov 15 '18 at 6:16
Blacktempel
2,88231739
2,88231739
asked Nov 14 '18 at 13:13
VahidVahid
1,89453684
asked Nov 14 '18 at 13:13
VahidVahid
1,89453684
asked Nov 14 '18 at 13:13
VahidVahid
1,89453684
1,89453684
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
1
You could hook up an event handler for the PropertyChanged event of the View in your callback:
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
MessageBox.Show("Refreshed!");
View newView = e.NewValue as View;
if (newView != null)
newView.PropertyChanged += NewView_PropertyChanged;
View oldView = e.OldValue as View;
if (oldView != null)
oldView.PropertyChanged -= NewView_PropertyChanged;
private static void NewView_PropertyChanged(object sender, PropertyChangedEventArgs e)
View view = (View)sender;
//view updated...
answered Nov 14 '18 at 13:22
mm8mm8
83.2k81831
Sounds a reasonable solution. Thank you. But then it will fire on every property change in View! And I do not want to hard-code the property name here! Isn't it possible to have some Refresh() method in the Control and a mechansim so that I can force it to execute via binding from outside?
– Vahid
Nov 14 '18 at 13:37
It will fire whenever the view fires the PropertyChanged event. What property name are you referring to?
– mm8
Nov 14 '18 at 13:41
My View may have other properties that raise OnPropertyChanged like Name, etc. I only want change in a specific property of View to trigger the Refresh() on CustomControl. What I want is a kind of mechansim in CustomControl so that I can bind to my ViewModel outside the Control.
– Vahid
Nov 14 '18 at 13:43
Maybe I should have a boolean RefreshRequested DP in CustomControl and bind it to imy view model outside the control as well?
– Vahid
Nov 14 '18 at 13:44
Either check the name of the property that raised the event in the control or raise another event in View.
– mm8
Nov 14 '18 at 13:54
|
show 1 more comment
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
1
You could hook up an event handler for the PropertyChanged event of the View in your callback:
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
MessageBox.Show("Refreshed!");
View newView = e.NewValue as View;
if (newView != null)
newView.PropertyChanged += NewView_PropertyChanged;
View oldView = e.OldValue as View;
if (oldView != null)
oldView.PropertyChanged -= NewView_PropertyChanged;
private static void NewView_PropertyChanged(object sender, PropertyChangedEventArgs e)
View view = (View)sender;
//view updated...
answered Nov 14 '18 at 13:22
mm8mm8
83.2k81831
Sounds a reasonable solution. Thank you. But then it will fire on every property change in View! And I do not want to hard-code the property name here! Isn't it possible to have some Refresh() method in the Control and a mechansim so that I can force it to execute via binding from outside?
– Vahid
Nov 14 '18 at 13:37
It will fire whenever the view fires the PropertyChanged event. What property name are you referring to?
– mm8
Nov 14 '18 at 13:41
My View may have other properties that raise OnPropertyChanged like Name, etc. I only want change in a specific property of View to trigger the Refresh() on CustomControl. What I want is a kind of mechansim in CustomControl so that I can bind to my ViewModel outside the Control.
– Vahid
Nov 14 '18 at 13:43
Maybe I should have a boolean RefreshRequested DP in CustomControl and bind it to imy view model outside the control as well?
– Vahid
Nov 14 '18 at 13:44
Either check the name of the property that raised the event in the control or raise another event in View.
– mm8
Nov 14 '18 at 13:54
|
show 1 more comment
1
You could hook up an event handler for the PropertyChanged event of the View in your callback:
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
MessageBox.Show("Refreshed!");
View newView = e.NewValue as View;
if (newView != null)
newView.PropertyChanged += NewView_PropertyChanged;
View oldView = e.OldValue as View;
if (oldView != null)
oldView.PropertyChanged -= NewView_PropertyChanged;
private static void NewView_PropertyChanged(object sender, PropertyChangedEventArgs e)
View view = (View)sender;
//view updated...
answered Nov 14 '18 at 13:22
mm8mm8
83.2k81831
Sounds a reasonable solution. Thank you. But then it will fire on every property change in View! And I do not want to hard-code the property name here! Isn't it possible to have some Refresh() method in the Control and a mechansim so that I can force it to execute via binding from outside?
– Vahid
Nov 14 '18 at 13:37
It will fire whenever the view fires the PropertyChanged event. What property name are you referring to?
– mm8
Nov 14 '18 at 13:41
My View may have other properties that raise OnPropertyChanged like Name, etc. I only want change in a specific property of View to trigger the Refresh() on CustomControl. What I want is a kind of mechansim in CustomControl so that I can bind to my ViewModel outside the Control.
– Vahid
Nov 14 '18 at 13:43
Maybe I should have a boolean RefreshRequested DP in CustomControl and bind it to imy view model outside the control as well?
– Vahid
Nov 14 '18 at 13:44
Either check the name of the property that raised the event in the control or raise another event in View.
– mm8
Nov 14 '18 at 13:54
|
show 1 more comment
1
1
1
You could hook up an event handler for the PropertyChanged event of the View in your callback:
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
MessageBox.Show("Refreshed!");
View newView = e.NewValue as View;
if (newView != null)
newView.PropertyChanged += NewView_PropertyChanged;
View oldView = e.OldValue as View;
if (oldView != null)
oldView.PropertyChanged -= NewView_PropertyChanged;
private static void NewView_PropertyChanged(object sender, PropertyChangedEventArgs e)
View view = (View)sender;
//view updated...
answered Nov 14 '18 at 13:22
mm8mm8
83.2k81831
You could hook up an event handler for the PropertyChanged event of the View in your callback:
private static void Refresh(DependencyObject d, DependencyPropertyChangedEventArgs e)
MessageBox.Show("Refreshed!");
View newView = e.NewValue as View;
if (newView != null)
newView.PropertyChanged += NewView_PropertyChanged;
View oldView = e.OldValue as View;
if (oldView != null)
oldView.PropertyChanged -= NewView_PropertyChanged;
private static void NewView_PropertyChanged(object sender, PropertyChangedEventArgs e)
View view = (View)sender;
//view updated...
answered Nov 14 '18 at 13:22
mm8mm8
83.2k81831
answered Nov 14 '18 at 13:22
mm8mm8
83.2k81831
answered Nov 14 '18 at 13:22
mm8mm8
83.2k81831
answered Nov 14 '18 at 13:22
mm8mm8
83.2k81831
83.2k81831
Sounds a reasonable solution. Thank you. But then it will fire on every property change in View! And I do not want to hard-code the property name here! Isn't it possible to have some Refresh() method in the Control and a mechansim so that I can force it to execute via binding from outside?
– Vahid
Nov 14 '18 at 13:37
It will fire whenever the view fires the PropertyChanged event. What property name are you referring to?
– mm8
Nov 14 '18 at 13:41
My View may have other properties that raise OnPropertyChanged like Name, etc. I only want change in a specific property of View to trigger the Refresh() on CustomControl. What I want is a kind of mechansim in CustomControl so that I can bind to my ViewModel outside the Control.
– Vahid
Nov 14 '18 at 13:43
Maybe I should have a boolean RefreshRequested DP in CustomControl and bind it to imy view model outside the control as well?
– Vahid
Nov 14 '18 at 13:44
Either check the name of the property that raised the event in the control or raise another event in View.
– mm8
Nov 14 '18 at 13:54
|
show 1 more comment
Sounds a reasonable solution. Thank you. But then it will fire on every property change in View! And I do not want to hard-code the property name here! Isn't it possible to have some Refresh() method in the Control and a mechansim so that I can force it to execute via binding from outside?
– Vahid
Nov 14 '18 at 13:37
It will fire whenever the view fires the PropertyChanged event. What property name are you referring to?
– mm8
Nov 14 '18 at 13:41
My View may have other properties that raise OnPropertyChanged like Name, etc. I only want change in a specific property of View to trigger the Refresh() on CustomControl. What I want is a kind of mechansim in CustomControl so that I can bind to my ViewModel outside the Control.
– Vahid
Nov 14 '18 at 13:43
Maybe I should have a boolean RefreshRequested DP in CustomControl and bind it to imy view model outside the control as well?
– Vahid
Nov 14 '18 at 13:44
Either check the name of the property that raised the event in the control or raise another event in View.
– mm8
Nov 14 '18 at 13:54
Sounds a reasonable solution. Thank you. But then it will fire on every property change in View! And I do not want to hard-code the property name here! Isn't it possible to have some Refresh() method in the Control and a mechansim so that I can force it to execute via binding from outside?
– Vahid
Nov 14 '18 at 13:37
Sounds a reasonable solution. Thank you. But then it will fire on every property change in View! And I do not want to hard-code the property name here! Isn't it possible to have some Refresh() method in the Control and a mechansim so that I can force it to execute via binding from outside?
– Vahid
Nov 14 '18 at 13:37
It will fire whenever the view fires the PropertyChanged event. What property name are you referring to?
– mm8
Nov 14 '18 at 13:41
It will fire whenever the view fires the PropertyChanged event. What property name are you referring to?
– mm8
Nov 14 '18 at 13:41
My View may have other properties that raise OnPropertyChanged like Name, etc. I only want change in a specific property of View to trigger the Refresh() on CustomControl. What I want is a kind of mechansim in CustomControl so that I can bind to my ViewModel outside the Control.
– Vahid
Nov 14 '18 at 13:43
My View may have other properties that raise OnPropertyChanged like Name, etc. I only want change in a specific property of View to trigger the Refresh() on CustomControl. What I want is a kind of mechansim in CustomControl so that I can bind to my ViewModel outside the Control.
– Vahid
Nov 14 '18 at 13:43
Maybe I should have a boolean RefreshRequested DP in CustomControl and bind it to imy view model outside the control as well?
– Vahid
Nov 14 '18 at 13:44
Maybe I should have a boolean RefreshRequested DP in CustomControl and bind it to imy view model outside the control as well?
– Vahid
Nov 14 '18 at 13:44
Either check the name of the property that raised the event in the control or raise another event in View.
– mm8
Nov 14 '18 at 13:54
Either check the name of the property that raised the event in the control or raise another event in View.
– mm8
Nov 14 '18 at 13:54
|
show 1 more comment
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