EventToCommandBehavior Enable/Disable

[FM1973]

Hello,
It would be nice if one could enable and disable an EventToCommandBehavior.

In my case I use the EventToCommandBehavior for Binding a command if a switch in a collectionview is toggled.
this works pretty well. The problem is, the EventToCommandBehavior also calls the command during loading the collectionview items.

[bijington]

You can control whether the Command will be executed using the CanExecute parameter. I appreciate this would rely on having some knowledge in the View Model that owns the Command property. Would that work?

[bijington]

If you have a view model that represents each item in the list then you could potentially have it handle the saving and you trigger that based on when the Switch is toggled through a binding to a boolean property on the view model. If that makes sense?

[IeuanWalker]

@FM1973 you could also have 2 bools in your model.

i.e. IntialValue + CurrentValue
Binding the CurrentValue to Toggle, when the command is triggered compare the IntialValue == CurrentValue and then do the API call if they differ.
If the API call is successful, update the IntialValue = CurrentValue

[IeuanWalker]

And as @bijington you could also handle it in the bindings and not have an event or command.

Using the new MVVM toolkit you can use the OnChanging method, which will give you the value it's about to change too. So you can compare the parameter value to the model value, i.e. -

[FM1973]

Thanks for your suggestions.
I´m talking about a collectionview of items (ObservableCollection). So OnXXXChanging won´t work.

[bijington]

it can work if the items in your ObservableCollection are observable objects. A brief example is below but note I have written it in the browser so it may not be complete.

public class ItemViewModel
{
    // Handle OnXXXChanging in here
}

public class MainViewModel
{
    public ObservableCollection<ItemViewModel> Items { get; }
}

[CliffAgius]

Closed and answered