WPF Binding syntax

Question

When to use "/" symbol in path? I thought "/" uses only when we work with XML, but today see example:

class ViewModel
{
    CollectionView Data {get;set;}
}

class BusinessObkect
{
    string Name {get;set;}
}

DataContext property of the window is set to an instance of the ViewModel class, Data property of the ViewModel instance is niitialized with a collection of BusinessObject objects.

if Text property of TextBox instance {Binding Path=Data/Name} all works normal, but if Text = {Binding Path=Data.Name} - binding error.

When I must use "/" instead of "." in bindings Path?

brunnerh · Accepted Answer · 2011-06-20 17:05:30Z

13

Why not ask the documentation:

Subproperties of a property can be specified by a syntax similar to that used in C#. For instance, the clause Path=ShoppingCart.Order sets the binding to the subproperty Order of the object or property ShoppingCart.

When the source is a collection view, the current item can be specified with a slash (/). For example, the clause Path=/ sets the binding to the current item in the view. When the source is a collection, this syntax specifies the current item of the default collection view.

(Collection view link added for convenience)

That's about as concise and complete as it gets. Using . notation with a collection to a property of one of its items does not even make sense. e.g. Collection.Date as opposed to Collection/Date (unless the collection itself actually has a Date property for some reason).

edited Jun 20, 2011 at 17:05

answered Jun 20, 2011 at 17:00

brunnerh

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Comments

Femaref · Accepted Answer · 2011-06-20 16:20:45Z

4

You need to use it when Data is a collection. / takes the current element of the Data collection and returns the Name property on it.

answered Jun 20, 2011 at 16:20

Femaref

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2 Comments

Ed Swangren Over a year ago

What do you mean by the "current element of [a] collection"? None of the collection types that I am familiar with have a concept of a current item in and of themselves.

Femaref Over a year ago

In this case, he uses a CollectionView on its own, it already has that. If you use an ObservableCollection<T> (or similar), the WPF engine wraps it into a CollectionView to supply this necessary infrastructure.

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