Button Bound To Command Won't Disable

Kevin Marois

Working on a WPF MVVM app... I have this button:

It's bound to RunCommand:

private ICommand _RunCommand;
public ICommand RunCommand
{
get
{
if (_RunCommand == null)
{
_RunCommand = new RelayCommand(runTest, runTestCanExecute);
}
return _RunCommand;
}
}

Here's the methods:

private void runTest()
{
isTesting = true;

var device = (from d in tempDevices
                where d.DeviceId == SelectedDevice.DeviceId
                select d).FirstOrDefault();

diag.ExecuteTest(device, SelectedTest);

}
private bool runTestCanExecute()
{
return !isTesting;
}

isTesting is defaulted to False. The button does not disable. Anyone see what's wrong?

If it's not broken, fix it until it is

SledgeHammer01

Are you sure its not disabled? You are overriding the content, so it may appear to be enabled, but really be not clickable because you aren't handling the disabled state.

Mycroft Holmes

Try this, change you button to use a Click="" event instead of a Command.

Never underestimate the power of human stupidity RAH

Kevin Marois

Ya, it's still responds to clicks.

If it's not broken, fix it until it is

SledgeHammer01

Copy & pasted your code into a test project and it disables just fine. Make sure your DataContext is set properly or it won't know where the command is. I.e. put a break point on your CanExecute handler and make sure its actually getting called.

Kevin Marois

Ok, I see what's going on. isTesting is somehow reverting to false by the time the CanExecute is called. Stay tuned.....

If it's not broken, fix it until it is

RobCroll

I haven't got VS at hand at the moment but couldn't you just do something along the lines of:

"You get that on the big jobs."

PaulLinton

Whenever you change isTesting you will need to call

RunCommand.OnCanExecuteChanged()

(If it isn't, you might want to make isTesting a property and call OnExecuteChanged from the Setter)