converting double.NaN to the relevant culture in converter wpf

Question

have a datatable which is being inserted with doubl.NaN when we dont have values. What i want to do is whenever i see double.Nan i want to put "-" instead, therefore i have a converter with the following code:

        if (value.ToString() == double.NaN.ToString())
        {
            return "-";
        }

everything worked perfectly on "en-us" culture, but when we use different culture (like "zn-cn") it doesnt work, due to the fact that "double.NaN.ToString()" results with a chinese word where value.ToString() is the normal "NaN".

i tried using double.parse() using the converters, nothing worked.

Update - ok the problem is that the converter gets the object as string and not as double this is the Xaml:

  <ControlTemplate TargetType="{x:Type DataGridCell}">
                <Border Background="Transparent"  Padding="10 8" BorderBrush="Transparent"  BorderThickness="1">
                    <Border.Resources>
                        <Style TargetType="ToolTip">
                            <Setter Property="OverridesDefaultStyle" Value="true"/>
                            <Setter Property="HasDropShadow" Value="False"/>
                            <Setter Property="VerticalOffset" Value="-46"/>
                            <Setter Property="HorizontalOffset" Value="10"/>
                            <Setter Property="Template">
                                <Setter.Value>
                                    <ControlTemplate TargetType="ToolTip">
                                        <General:TextTooltip TitleStyle="{StaticResource NumericTableToolTipTitleStyle}"  Content="{TemplateBinding Content}" ContentStringFormat="G"  ContentStyle="{StaticResource NumericTableToolTipContentStyle}"/>
                                    </ControlTemplate>
                                </Setter.Value>
                            </Setter>
                        </Style>
                    </Border.Resources>
                    <TextBlock x:Name="tbCellText" Text="{Binding RelativeSource={RelativeSource TemplatedParent}, 
                               Path=Content.Text, Converter={StaticResource NumericTableCellContentConverter}, ConverterCulture={x:Static gl:CultureInfo.CurrentCulture}}"
                               ToolTip="{Binding ElementName=tbCellText, Path=Text}"
                               TextWrapping="Wrap"/>
                </Border>
            </ControlTemplate>

is there any way to preserve the type of the object?

i know i could just do a comparison with "NaN" but i would like more generic solution for that matter.

BTW, converters have converterculture as one of the parameters — Vlad, Jul 19 '12 at 14:58
yea i know but it doesnt help as long as the value is of string type... — Ori Price, Jul 19 '12 at 15:02
@OriPrice see my answer, you're binding to the wrong property. — Lee Louviere, Jul 19 '12 at 15:35

score 2 · Answer 1 · answered Jul 19 '12 at 14:01

2

When you bind to a property of type double the converter gets a value parameter of type double. You could easily do this:

if (double.IsNaN((double)value))
{
    return "-";
}

answered Jul 19 '12 at 14:01

Clemens

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thanks, but i tried it and it doesnt work. the value cannot be converted to double.... – Ori Price Jul 19 '12 at 14:32
i thinks its because the value object is being converted to string ("NaN") somehow – Ori Price Jul 19 '12 at 14:36
Isn't the property you're binding to of type `double`? If it's a string that's always "NaN" when the value is `NaN`, your comparison could be as simple as `if (value as string == "NaN")`. – Clemens Jul 19 '12 at 14:38
i am inserting it to a datatable (there its a double) then i am binding the datatable to a datagrid in the xaml with the relevant converter. i would expect that the value that arrive to the converter will stay the same (double) but apperantly it doesnt.... i dont want to relay on strings... is there any way to convert the string "NAN" to double? – Ori Price Jul 19 '12 at 14:46
With "relevant converter" you mean the converter we're talking about here? If the property that you bind to is of type `double`, then the converter gets a `value` parameter of type `double`. If that's not the case, you have to find out why. Perhaps you post the relevant XAML (with the binding). – Clemens Jul 19 '12 at 14:51
i've confirmed that its actually a string so you are right and i think the problem is that its being converted to string in the control template. – Ori Price Jul 19 '12 at 14:55
maybe the problem is that i am converting the value AFTER binding the data table to a data grid and when extracting the value from data grid would always be a string? – Ori Price Jul 19 '12 at 15:04
Yes indeed, you should somehow bind directly to the data. – Clemens Jul 19 '12 at 15:06

Vlad · Answer 2 · 2012-07-19T14:20:30.717

1

if (double.IsNaN(value)) ... will do in any locale.

Documentation link: http://msdn.microsoft.com/en-us/library/system.double.isnan.aspx

BTW, direct comparison to double.NaN (if (value == double.NaN)) won't work, as the comparison of NaN to NaN returns false! You could however detect NaN by such a trick: if (value != value) ... (this holds true only for NaNs). But an explicit test double.IsNaN is more readable.

Edit: as other answers suggest, inside the converter your value is perhaps not double, but object. So you'd need to include a check:

if (!(value is double))
    return ""; // or signal an error, or whatever
double d = (double)value;
if (double.IsNaN(d))
    return "-";
...

edited Jul 19 '12 at 14:20

answered Jul 19 '12 at 13:58

Vlad

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thanks, but i tried it and it doesnt work. the value cannot be converted to double.... – Ori Price Jul 19 '12 at 14:35
@Ori: Well, could you please look in the debugger, what is the actual type of `value`? – Vlad Jul 19 '12 at 14:42
yes its a string instead of double. updated the post (added the relevant Xaml) – Ori Price Jul 19 '12 at 14:58
@Ori: Hmmm. Where does this string come from? Which code have converted `double.NaN` to the localized string? – Vlad Jul 19 '12 at 14:58

score 1 · Answer 3 · answered Jul 19 '12 at 14:00

1

One little addition to Vlad:

if (value is double && double.IsNaN((double)value))

answered Jul 19 '12 at 14:00

Alexander Efimov

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thanks, but i tried it and it doesnt work. the value cannot be converted to double.... – Ori Price Jul 19 '12 at 14:34
what type of value do you have in a value parameter? – Alexander Efimov Jul 19 '12 at 14:37
string. i dont know where it comes from. – Ori Price Jul 19 '12 at 15:07
That means you're binding to a string value. Why don't you consider binding to an original double value? Try to remove "Path=Content.Text," part from your binding. I suppose, DataContext of the DataGridCell should be the original value. – Alexander Efimov Jul 19 '12 at 15:12
actually i stll have a problem. the datacontext of the DataGridCell is of a DataRow type. not a specific cell. so i get the whole row in the converter. – Ori Price Jul 22 '12 at 08:29

score 0 · Answer 4 · answered Jul 19 '12 at 15:35

0

Don't bind to the content.text property in your datagridcell. That's why the value is coming in as a string.

Try storing the data value in the Tag property of the TextBlock and bind to that, then in property updated code, set the value of the text.

answered Jul 19 '12 at 15:35

Lee Louviere

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score 0 · Accepted Answer · answered May 04 '15 at 19:16

Solution - the problem is that i was binding the data table to a datagrid and only after that i am converting all values. Extracting values from data grid is always of type strig so there was my problem. i just need to use the converter while binding directly to the data table instead to datagrid cells.

converting double.NaN to the relevant culture in converter wpf

5 Answers5