CODEWITHSUNDEEP
wpfbindinguser-controlsidataerrorinfo
user844222
user844222

Reputation: 21

Notification of Collection Update for IDataErrorInfo Validation

I would like to notify the binding system in WPF of a change in a collection's item so that a validation through IDataErrorInfo gets reevaluated whenever an item inside a collection changes. I have a custom list type which implements INotifyCollectionChanged (and works properly). But somehow the validation logic is never called, because (or at least I am assuming) that this notification does not reach the right place. Is this scenario even possible? What have I missed?

[Edit]

So basically the "architecture" is the following:

  1. MVVM base class implements IDataErrorInfo and you can register DataValidators with lambdas in the derived MVVM classes, such as:
RegisterDataValidator(() => People, () => (People.Count == 0) ? "At least one person must be specified" : null);

The indexer on the base class checks the registered validator and returns the returned by it.

  1. I have a SmartBindingList<T> where T: INotifyPropertyChange which is basically a list that when items are added to it, registers the items' PropertyChangedEvent and reacts to these events by firing the CollectionChanged event on the class itself:
private void OnSubPropertyChanged (object sender, PropertyChangedEventArgs e)
    {
        if (sender is T1)
        {
            if (CollectionChanged != null)
            {
                NotifyCollectionChangedEventArgs eventArgs = new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, sender, sender);
                CollectionChanged(this, eventArgs);
            }
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(myPropertyName));
            }
        }
    }

So all this works nicely, but when the code runs on the CollectionChanged(this, eventArgs) line, nothing happens in terms of validation. It should be wired up correctly, because when I add something to the collection, it works perfectly. What am I missing?

Upvotes: 2

Views: 784

Answers (1)

Phil
Phil

Reputation: 42991

This is a bit of stab in the dark without some example code, but try raising your OnPropertyChanged notification for the properties that have changed. This should cause validation to be re-evaluated.

Upvotes: 1

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