Use StringFormat to add a string to a WPF XAML binding

Question

I have a WPF 4 application that contains a TextBlock which has a one-way binding to an integer value (in this case, a temperature in degrees Celsius). The XAML looks like this:

<TextBlock x:Name="textBlockTemperature"><Run Text="{Binding CelsiusTemp, Mode=OneWay}"/></TextBlock>

This works fine for displaying the actual temperature value but I'd like to format this value so it includes °C instead of just the number (30°C instead of just 30). I've been reading about StringFormat and I've seen several generic examples like this:

// format the bound value as a currency
<TextBlock Text="{Binding Amount, StringFormat={}{0:C}}" />

and

// preface the bound value with a string and format it as a currency
<TextBlock Text="{Binding Amount, StringFormat=Amount: {0:C}}"/>

Unfortunately, none of the examples I've seen have appended a string to the bound value as I'm trying to do. I'm sure it's got to be something simple but I'm not having any luck finding it. Can anyone explain to me how to do that?

Answer 1

Your first example is effectively what you need:

<TextBlock Text="{Binding CelsiusTemp, StringFormat={}{0}°C}" />

Answer 2

Here's an alternative that works well for readability if you have the Binding in the middle of the string or multiple bindings:

<TextBlock>
  <Run Text="Temperature is "/>
  <Run Text="{Binding CelsiusTemp}"/>
  <Run Text="°C"/>  
</TextBlock>

<!-- displays: 0°C (32°F)-->
<TextBlock>
  <Run Text="{Binding CelsiusTemp}"/>
  <Run Text="°C"/>
  <Run Text=" ("/>
  <Run Text="{Binding Fahrenheit}"/>
  <Run Text="°F)"/>
</TextBlock>

Answer 3

Please note that using StringFormat in Bindings only seems to work for "text" properties. Using this for Label.Content will not work

Answer 4

In xaml

<TextBlock Text="{Binding CelsiusTemp}" />

In ViewModel, this way setting the value also works:

 public string CelsiusTemp
        {
            get { return string.Format("{0}°C", _CelsiusTemp); }
            set
            {
                value = value.Replace("°C", "");
              _CelsiusTemp = value;
            }
        }