PriorityBinding-对Label中的每个绑定使用不同的StringFormat

Question

In my WPF project, I have a Label :

<Label Grid.Column="1"
       Grid.Row="1">
    <PriorityBinding>
        <Binding Path="Worker.Employer.Name" StringFormat="Employer: {0}" />
        <Binding Source="Unemployed" />
    </PriorityBinding>
</Label>

The StringFormat on doesn't seem to do anything. However, if I add this:

<Label.ContentStringFormat>
    Employer: {0}
</Label.ContentStringFormat>

... the formatting works, but it affects both bindings. How can I apply the StringFormat to only the top binding?

Update: So short of using a TextBlock instead of a Label , is there any way to accomplish this?

Answer 1

StringFormat is for string (eg TextBlock.Text), but label.Content is type of object and there for you have to use ContentStringFormat for Label.

edit: to your question - if you can chang label to TextBlock then you have no problems anymore. but if you wanna stay with label i would guess you have to use a converter to apply your string format.

Answer 2

As already explained StringFormat only works when the target property type is text.

One solution would be to use a ValueConverter to format the result, you can pass in the format string as the ConverterParameter.

Failing that create an attached DependencyProperty of type string

public static class Helper {
    public static readonly DependencyProperty TextProperty = DependencyProperty.RegisterAttached("Text", typeof(string), typeof(Helper));

   public static string GetText(DependencyObject o) {
     return (string)o.GetValue(TextProperty);
   }

   public static void SetText(DependencyObject o, string value) {
      o.SetValue(TextProperty,value);
   }
}

Then you can do

<Label Grid.Column="1"
       Grid.Row="1" 
       Content="{Binding RelativeSource={RelativeSource Self}, Path=(ui:Helper.Text)}">
    <ui:Helper.Text>
    <PriorityBinding>
        <Binding Path="Worker.Employer.Name" StringFormat="Employer: {0}" />
        <Binding Source="Unemployed" />
    </PriorityBinding>
    </ui:Helper.Text>
</Label>

The problem describe in the comments may be related to This Question and so the XAML might need to look like this.

<Label Grid.Column="1"
       Grid.Row="1" >
       <Binding RelativeSource="{RelativeSource Self}"  Path="(ui:Helper.Text)" />
      <ui:Helper.Text>
      <PriorityBinding>
          <Binding Path="Worker.Employer.Name" StringFormat="Employer: {0}" />
          <Binding Source="Unemployed" />
      </PriorityBinding>
      </ui:Helper.Text>
</Label>

Or from this MSDN question you could do

<Label Grid.Column="1"
       Grid.Row="1" >
      <ui:Helper.Text>
      <PriorityBinding>
          <Binding Path="Worker.Employer.Name" StringFormat="Employer: {0}" />
          <Binding Source="Unemployed" />
      </PriorityBinding>
      </ui:Helper.Text>
      <Label.Content>
         <Binding RelativeSource="{RelativeSource Self}"  Path="(ui:Helper.Text)" />
      </Label.Content>
    </Label>

Make sure that you bind the xmlns for ui to the namespace of your Helper class

You could always put the Content relative source binding into a style to avoid repeating it for all labels.