WinRT XAML : Binding text to decimal causes

Question

When binding a textbox's Text property to a decimal on a view model using two way binding, I'm receiving the exception below.  The exception occurs when leaving the text box.  It works fine when using a float.

Object of type 'System.String' cannot be converted to type 'System.Decimal'.

Value does not fall within the expected range.

<Page
    x:Class="DecimalBindingTest.BlankPage"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:DecimalBindingTest"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d">
    <Page.DataContext>
        <local:ViewModel />
    </Page.DataContext>
    
    <StackPanel>
        <TextBox Text="{Binding Decimal, Mode=TwoWay}" />
     </StackPanel>
</Page>

public class ViewModel
    {
        private decimal m_Decimal;
        public decimal Decimal
        {
            get { return m_Decimal; }
            set { m_Decimal = value; }
        }
    }

Answer 1

This is by design.  There's a long and complicated answer for this which I am not going into.  Please use float.

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Matt Small - Microsoft Escalation Engineer - Forum Moderator If my reply answers your question, please mark this post as answered.

Answer 2

Hey Matt: Actually I'd like to understand this limitation better. Is there a reference you can point me to why this is?

Answer 3

It would be nice to know, but he marked his previous answer as the official answer.

Answer 4

Had the same problem, and found this Forum post.  Agree, would be nice to understand why this behaviour.  Not had this same issue with WP7 (at least with other controls), so not clear why it shouldn't be supported. 

Can we at least get a link to the long and complicated answer somewhere else?

Thanks.

Answer 5

Too bad we can't vote as Unhelpful

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Luc Morin, T.P. http://www.stlm.ca

Answer 6

In case some other poor soul runs into this question, there is a simple solution.  Creating a IValueConverter solves the problem as described by Stefan here http://social.msdn.microsoft.com/Forums/is/winappswithcsharp/thread/b6099324-e66c-42ef-9bfe-a0f022e2b6ab.

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Darrel