MessageBoxResult Strange Behaviour

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I have some logic running within a a Property. However, when attempting to use MessageBoxResult to find user's response (Yes or No) and based on that I would run the logic that will set the Property or quit/return, the set accessor is always called a second time.

In the example below, the issue happens only when the user clicks No:

C#

private SomeType _SelectedItem;
public SomeType  SelectedItem
{
    get { return _SelectedItem; }
    set
    {
        if (_SelectedItem != value)
        {
            var result = MessageBox.Show("Confirm your selection", "Confirm", MessageBoxButton.YesNo);
            if (result == MessageBoxResult.Yes)
                _SelectedItem = value;
            RaisePropertyChanged();
        }
    }
}

Posted 17-Nov-14 6:05am

BeeDev

Updated 17-Nov-14 10:19am

v3

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Maciej Los 17-Nov-14 13:48pm

Why do you use var result instead of MessageBoxResult result =?

if (result == MessageBoxResult.Yes)
{
                        _SelectedConfig = value;
                    RaisePropertyChanged();
}

BeeDev 17-Nov-14 15:34pm

To keep it short that is all.

Maciej Los 17-Nov-14 15:59pm

So... Quickly, quickly... accept my answer ;)

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Maciej Los · Answer 1 · 2014-11-17T08:13:00

Solution 1

Please, see my comment to the question.

There is no strange MessageBox behaviour. It's totally unrelated to MessageBox.

Inside a setter RaisePropertyChanged is called no matter of MessageBox result. To correct it you need to add '{' and '}', because only one line of statement is executed after if condition.

See: if-else (C# reference)[^]

Posted 17-Nov-14 8:13am

Maciej Los

Comments

BeeDev 17-Nov-14 15:55pm

Could you please clarify a little bit more; add the {brackets} around what?
The only thing I did is moving RaisePropertyChanged outside the brackets since you said it is called no matter what; however, that didn't change anything, "Set" still being hit 2 times.
if (result == MessageBoxResult.Yes)
{
_SelectedConfig = value;
}
RaisePropertyChanged();

Maciej Los 17-Nov-14 16:11pm

Please, be more attentive. The second bracket should be after this line: RaisePropertyChanged() } <--here ;)

BeeDev 17-Nov-14 16:23pm

You make me feel pretty dumb :)
Here is what I have; however, the issue still there.
if (result == MessageBoxResult.Yes)
{
_SelectedItem = value;
RaisePropertyChanged();
}

BeeDev 17-Nov-14 16:58pm

I ended up handling the logic in Code Behind any way since it is UI related.