Substring a bound String

Question

What I want is to bind a string to a textblock or datatrigger (basically some WPF object) and take a part of the string. This string will be delimited. So, for example, I have this string:

String values = "value1|value2";

And I have two controls - txtBlock1 and txtBlock2.

In txtBlock1 I would like to set the Text property like Text={Binding values}. In txtBlock2 I would like to set the Text property like Text={Binding values}.

Obviously this will display the same string so I need some sort of StringFormat expression to add to this binding to substring values so that txtBlock1 reads value1 and txtBlock2 reads value2.

I've had a good read about and it seems like this: Wpf Binding Stringformat to show only first character is the typical proposed solution. But it seems awfully long-winded for what I'm trying to achieve here.

Thanks a lot for any help in advance.

score 2 · Accepted Answer · answered Feb 07 '12 at 12:45

What you need here is a converter. Add a converter parameter to indicate the index.

public class DelimiterConverter : IValueConverter
{
    public object Convert(Object value, Type targetType, object parameter, CultureInfo culture)
    {
        string[] values = ((string)value).Split("|");
        int index = int.Parse((string)parameter);
        return values[index];
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return "";
    }

Then you just specify the index of the value in XAML with the ConverterParameter attribute.

score 1 · Answer 2 · answered Feb 07 '12 at 12:47

I would use a value converter as explained in the example your linked.

But if you want something that is more straightforward, you could use the following property and bindings:

public string[] ValueArray
{
    get
    {
        return values.Split('|');
    }
}

<TextBlock Text="{Binding ValueArray[0]}" />
<TextBlock Text="{Binding ValueArray[1]}" />

But take care of what could happen if values is either null or doesn't contain |.

score 1 · Answer 3 · answered Feb 07 '12 at 12:54

1

If you just have two string you can simply do:

<TextBlock Text=Text={Binding value1}/>
<TextBlock Text=Text={Binding value2}/>

and

public string value1
{
   get{return values.Split('|')[0]}
   set{values = value + values.Remove(0, values.IndexOf('|')+1)}
}
public string value2 ....
public string values ...

In fact you can write a function for set value and get value for related index (extend above approach),But if you don't like this syntax, IMO what you referred is best option for you.

answered Feb 07 '12 at 12:54

Saeed Amiri

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The textblock I'm binding the string to will be as part of a datatemplate for listbox items. So the string will differ for each item. Thanks a lot for your reply, I'm sure I can use your solution here somehow. – SkonJeet Feb 07 '12 at 13:08

Substring a bound String

3 Answers3

Linked