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QuestionUI Validation Problem Pin
Kevin Marois10-Oct-23 14:10
professionalKevin Marois10-Oct-23 14:10 
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Richard Deeming10-Oct-23 23:13
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GeneralRe: UI Validation Problem Pin
Kevin Marois12-Oct-23 8:25
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GeneralRe: UI Validation Problem Pin
Richard Deeming12-Oct-23 22:34
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AnswerRe: UI Validation Problem Pin
Gerry Schmitz12-Oct-23 9:52
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GeneralRe: UI Validation Problem Pin
Kevin Marois12-Oct-23 15:54
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GeneralRe: UI Validation Problem Pin
Gerry Schmitz12-Oct-23 20:12
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GeneralRe: UI Validation Problem Pin
Kevin Marois16-Oct-23 13:50
professionalKevin Marois16-Oct-23 13:50 
OK, I don't get what's wrong here.

Here's the CustomerName in my CustomerView
<TextBox Grid.Row="1" 
            Grid.Column="0"
            Text="{Binding Customer.CustomerName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, ValidatesOnNotifyDataErrors=True}"
            IsEnabled="{Binding AreFieldsEnabled}">

<pre>
<Validation.ErrorTemplate>
    <ControlTemplate>
        <StackPanel>
            <AdornedElementPlaceholder/>
            <ItemsControl ItemsSource="{Binding}">
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding ErrorContent}" Foreground="Red" />
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </StackPanel>
    </ControlTemplate>
</Validation.ErrorTemplate>



Here's the VM
private void Customer_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
    IsChanged = true;

    ValidateCustomerName();
}

private void ValidateCustomerName()
{
    ClearErrors(nameof(Customer.CustomerName));

    if (string.IsNullOrWhiteSpace(Customer.CustomerName))
    {
        AddError(nameof(Customer.CustomerName), "The Customer Name cannot be empty.");
    }
}
When I clear out the CustomerName field, the ValidateCustomerName method fires, and the error is added to the errors collection. I just don't see the error text on the UI.

However, if instead of binding to Customer.CustomerName, if I put a string property on the VM called CustomerName and use that, then I see the error text.
In theory, theory and practice are the same. But in practice, they never are.”
If it's not broken, fix it until it is.
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QuestionUI Validation Questions Pin
Kevin Marois29-Sep-23 16:54
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AnswerRe: UI Validation Questions Pin
Richard Deeming1-Oct-23 22:43
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