WPF Commands---How to attach to ViewModel properly from View for logic?
I have seen quite a few different posts regarding this, but am still confused as to what the proper way to do this is. I am implementing RelayCommand and IRequireViewID to do things like call a WindowsManager class to close windows from the view where it doesn't need to know what window it is calling, etc.
However, situations that arise like this is where I am unsure how to implement things properly.
So basically I have a command in the viewModel where you click a button and I need to save data to a DB once this happens. How do I have the command in the View but then put the logic for this into the ViewModel? IE, basically the ViewModel would need to know when the Command is called. I mean I could always put a static method in the viewmodel and call it from the view but I am assuming that probably is not a good way to implement it, ie MyViewModel.RedValidation from the view.
RelayCommand Class
public class RelayCommand : ICommand
{
private Action commandTask;
public RelayCommand(Action commandToRun)
{
commandTask = commandToRun;
}
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
commandTask();
}
}
View
public ICommand ValidateRed
{
get => new RelayCommand(RedValidation);
}
private void RedValidation()
{
//SAVE Data To DB <----This should be in the ViewModel though right?
}
XAML:
<Button Name="ValidateBtn" Style="{StaticResource mainButtons}" Content="Validate Email" Width="100"
HorizontalAlignment="Left" Command="{Binding ValidateRed}"/>
c# wpf mvvm command viewmodel
asked Nov 27 '18 at 17:45
MattEMattE
343517
add a comment |
I have seen quite a few different posts regarding this, but am still confused as to what the proper way to do this is. I am implementing RelayCommand and IRequireViewID to do things like call a WindowsManager class to close windows from the view where it doesn't need to know what window it is calling, etc.
However, situations that arise like this is where I am unsure how to implement things properly.
So basically I have a command in the viewModel where you click a button and I need to save data to a DB once this happens. How do I have the command in the View but then put the logic for this into the ViewModel? IE, basically the ViewModel would need to know when the Command is called. I mean I could always put a static method in the viewmodel and call it from the view but I am assuming that probably is not a good way to implement it, ie MyViewModel.RedValidation from the view.
RelayCommand Class
public class RelayCommand : ICommand
{
private Action commandTask;
public RelayCommand(Action commandToRun)
{
commandTask = commandToRun;
}
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
commandTask();
}
}
View
public ICommand ValidateRed
{
get => new RelayCommand(RedValidation);
}
private void RedValidation()
{
//SAVE Data To DB <----This should be in the ViewModel though right?
}
XAML:
<Button Name="ValidateBtn" Style="{StaticResource mainButtons}" Content="Validate Email" Width="100"
HorizontalAlignment="Left" Command="{Binding ValidateRed}"/>
c# wpf mvvm command viewmodel
asked Nov 27 '18 at 17:45
MattEMattE
343517
In your example the only thing in the view, next to the UI, is the trigger. Which triggers the command on your viewmodel. The binding will let it know when it's called. Actually, the bliss is the other way around. The view doesn't know about the command, or what's been triggered. This is what separation of concerns is about. The view should only care about presentation, and the viewmodel provides whatever it needs.
– Funk
Nov 27 '18 at 19:25
"SAVE Data To DB" most definitely should not be in View or in ViewModel. it should be in a data-access layer
– ASh
Nov 27 '18 at 20:26
add a comment |
I have seen quite a few different posts regarding this, but am still confused as to what the proper way to do this is. I am implementing RelayCommand and IRequireViewID to do things like call a WindowsManager class to close windows from the view where it doesn't need to know what window it is calling, etc.
However, situations that arise like this is where I am unsure how to implement things properly.
So basically I have a command in the viewModel where you click a button and I need to save data to a DB once this happens. How do I have the command in the View but then put the logic for this into the ViewModel? IE, basically the ViewModel would need to know when the Command is called. I mean I could always put a static method in the viewmodel and call it from the view but I am assuming that probably is not a good way to implement it, ie MyViewModel.RedValidation from the view.
RelayCommand Class
public class RelayCommand : ICommand
{
private Action commandTask;
public RelayCommand(Action commandToRun)
{
commandTask = commandToRun;
}
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
commandTask();
}
}
View
public ICommand ValidateRed
{
get => new RelayCommand(RedValidation);
}
private void RedValidation()
{
//SAVE Data To DB <----This should be in the ViewModel though right?
}
XAML:
<Button Name="ValidateBtn" Style="{StaticResource mainButtons}" Content="Validate Email" Width="100"
HorizontalAlignment="Left" Command="{Binding ValidateRed}"/>
c# wpf mvvm command viewmodel
asked Nov 27 '18 at 17:45
MattEMattE
343517
I have seen quite a few different posts regarding this, but am still confused as to what the proper way to do this is. I am implementing RelayCommand and IRequireViewID to do things like call a WindowsManager class to close windows from the view where it doesn't need to know what window it is calling, etc.
However, situations that arise like this is where I am unsure how to implement things properly.
So basically I have a command in the viewModel where you click a button and I need to save data to a DB once this happens. How do I have the command in the View but then put the logic for this into the ViewModel? IE, basically the ViewModel would need to know when the Command is called. I mean I could always put a static method in the viewmodel and call it from the view but I am assuming that probably is not a good way to implement it, ie MyViewModel.RedValidation from the view.
RelayCommand Class
public class RelayCommand : ICommand
{
private Action commandTask;
public RelayCommand(Action commandToRun)
{
commandTask = commandToRun;
}
public bool CanExecute(object parameter)
{
return true;
}
public event EventHandler CanExecuteChanged;
public void Execute(object parameter)
{
commandTask();
}
}
View
public ICommand ValidateRed
{
get => new RelayCommand(RedValidation);
}
private void RedValidation()
{
//SAVE Data To DB <----This should be in the ViewModel though right?
}
XAML:
<Button Name="ValidateBtn" Style="{StaticResource mainButtons}" Content="Validate Email" Width="100"
HorizontalAlignment="Left" Command="{Binding ValidateRed}"/>
c# wpf mvvm command viewmodel
c# wpf mvvm command viewmodel
asked Nov 27 '18 at 17:45
MattEMattE
343517
asked Nov 27 '18 at 17:45
MattEMattE
343517
edited Nov 27 '18 at 17:49
MattE
asked Nov 27 '18 at 17:45
MattEMattE
343517
asked Nov 27 '18 at 17:45
MattEMattE
343517
asked Nov 27 '18 at 17:45
MattEMattE
343517
343517
In your example the only thing in the view, next to the UI, is the trigger. Which triggers the command on your viewmodel. The binding will let it know when it's called. Actually, the bliss is the other way around. The view doesn't know about the command, or what's been triggered. This is what separation of concerns is about. The view should only care about presentation, and the viewmodel provides whatever it needs.
– Funk
Nov 27 '18 at 19:25
"SAVE Data To DB" most definitely should not be in View or in ViewModel. it should be in a data-access layer
– ASh
Nov 27 '18 at 20:26
add a comment |
In your example the only thing in the view, next to the UI, is the trigger. Which triggers the command on your viewmodel. The binding will let it know when it's called. Actually, the bliss is the other way around. The view doesn't know about the command, or what's been triggered. This is what separation of concerns is about. The view should only care about presentation, and the viewmodel provides whatever it needs.
– Funk
Nov 27 '18 at 19:25
"SAVE Data To DB" most definitely should not be in View or in ViewModel. it should be in a data-access layer
– ASh
Nov 27 '18 at 20:26
In your example the only thing in the view, next to the UI, is the trigger. Which triggers the command on your viewmodel. The binding will let it know when it's called. Actually, the bliss is the other way around. The view doesn't know about the command, or what's been triggered. This is what separation of concerns is about. The view should only care about presentation, and the viewmodel provides whatever it needs.
– Funk
Nov 27 '18 at 19:25
In your example the only thing in the view, next to the UI, is the trigger. Which triggers the command on your viewmodel. The binding will let it know when it's called. Actually, the bliss is the other way around. The view doesn't know about the command, or what's been triggered. This is what separation of concerns is about. The view should only care about presentation, and the viewmodel provides whatever it needs.
– Funk
Nov 27 '18 at 19:25
"SAVE Data To DB" most definitely should not be in View or in ViewModel. it should be in a data-access layer
– ASh
Nov 27 '18 at 20:26
"SAVE Data To DB" most definitely should not be in View or in ViewModel. it should be in a data-access layer
– ASh
Nov 27 '18 at 20:26
add a comment |
1 Answer
1
active
oldest
votes
Everything you have in "View" should be in "ViewModel". Commands are properties of the view model, not the view (also, you shouldn't be binding against the view 99% of the time).
Once you have changed that, it should fall into place the way you expect.
answered Nov 27 '18 at 17:48
BradleyDotNETBradleyDotNET
52k87190
add a comment |
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1 Answer
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votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
Everything you have in "View" should be in "ViewModel". Commands are properties of the view model, not the view (also, you shouldn't be binding against the view 99% of the time).
Once you have changed that, it should fall into place the way you expect.
answered Nov 27 '18 at 17:48
BradleyDotNETBradleyDotNET
52k87190
add a comment |
Everything you have in "View" should be in "ViewModel". Commands are properties of the view model, not the view (also, you shouldn't be binding against the view 99% of the time).
Once you have changed that, it should fall into place the way you expect.
answered Nov 27 '18 at 17:48
BradleyDotNETBradleyDotNET
52k87190
add a comment |
Everything you have in "View" should be in "ViewModel". Commands are properties of the view model, not the view (also, you shouldn't be binding against the view 99% of the time).
Once you have changed that, it should fall into place the way you expect.
answered Nov 27 '18 at 17:48
BradleyDotNETBradleyDotNET
52k87190
Everything you have in "View" should be in "ViewModel". Commands are properties of the view model, not the view (also, you shouldn't be binding against the view 99% of the time).
Once you have changed that, it should fall into place the way you expect.
answered Nov 27 '18 at 17:48
BradleyDotNETBradleyDotNET
52k87190
answered Nov 27 '18 at 17:48
BradleyDotNETBradleyDotNET
52k87190
answered Nov 27 '18 at 17:48
BradleyDotNETBradleyDotNET
52k87190
answered Nov 27 '18 at 17:48
BradleyDotNETBradleyDotNET
52k87190
52k87190
add a comment |
add a comment |
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In your example the only thing in the view, next to the UI, is the trigger. Which triggers the command on your viewmodel. The binding will let it know when it's called. Actually, the bliss is the other way around. The view doesn't know about the command, or what's been triggered. This is what separation of concerns is about. The view should only care about presentation, and the viewmodel provides whatever it needs.
– Funk
Nov 27 '18 at 19:25
"SAVE Data To DB" most definitely should not be in View or in ViewModel. it should be in a data-access layer
– ASh
Nov 27 '18 at 20:26