Andy De George
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title, ms.date, dev_langs, helpviewer_keywords, ms.assetid
| title | ms.date | dev_langs | helpviewer_keywords | ms.assetid | ||||
|---|---|---|---|---|---|---|---|---|
| How to: Produce a Value Based on a List of Bound Items | 03/30/2017 |
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b3d06378-b511-4181-95aa-316d60c9229b |
How to: Produce a Value Based on a List of Bound Items
xref:System.Windows.Data.MultiBinding allows you to bind a binding target property to a list of source properties and then apply logic to produce a value with the given inputs. This example demonstrates how to use xref:System.Windows.Data.MultiBinding.
Example
In the following example, NameListData refers to a collection of PersonName objects, which are objects that contain two properties, firstName and lastName. The following example produces a xref:System.Windows.Controls.TextBlock that shows the first and last names of a person with the last name first.
[!code-xamlMultiBinding#Resources1]
[!code-xamlMultiBinding#Resources2]
[!code-xamlMultiBinding#MultiBindingTextBox2]
[!code-xamlMultiBinding#Window]
To understand how the last-name-first format is produced, let's take a look at the implementation of the NameConverter:
[!code-csharpMultiBinding#3] [!code-vbMultiBinding#3]
NameConverter implements the xref:System.Windows.Data.IMultiValueConverter interface. NameConverter takes the values from the individual bindings and stores them in the values object array. The order in which the xref:System.Windows.Data.Binding elements appear under the xref:System.Windows.Data.MultiBinding element is the order in which those values are stored in the array. The value of the xref:System.Windows.Data.MultiBinding.ConverterParameter%2A attribute is referenced by the parameter argument of the xref:System.Windows.Data.MultiBinding.Converter%2A method, which performs a switch on the parameter to determine how to format the name.