Wpf command canexecute not updating

I know the binding is working because I created a behavior that receives a target binding and raise the Can Execute when the the binding changes.With this behavior, the Can Execute is called normally.When using the Relay Command class, a command class used for MVVM development, you may find times when a button that is enabled or disabled based on Relay Command.Can Execute does not refresh until a keyboard or mouse click.This code works mostly correct but i can not make method Can Save Item to work properly.I don't know how to tell to Save Command that properties of View Model was changed.It takes an expression representing a property and adds it to an internal collection.In the Initialize method (lines 17-24), we use the Messenger to register for the Property Changed Message Base notification.

Invalidate Requery Suggested and i tried to use their some times but i don't know how to do it properly and it didn't take an effect. Set it to true whenever you change any field (add logic to the setters for properties to do this) and have your save command check the isdirty, run validation and then submit if all conditions are met.When using commands, usually in an MVVM scenario, we can define a method, Can Execute, that determines whether a command can execute in its current state.In a such situation, if the Can Execute handler returns , the associated command can’t be invoked: if the command is bound, for example, to a Button, the latter will be automatically disabled.The command parameter is set but doesn't seem to change.After load the window, the button remains disabled.

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