问题
I am trying to display a set of data using a DataTemplate in an ItemsControl, with the ItemsPanel set as a uniform grid of size 3 x 3. The ItemsSource of the ItemsControl is set to bind to a CollectionViewSource which filters the source collection based on a search term. This all works fine.
The list I am binding to is of an arbitrary size, but I only want 9 results to be displayed, but I can't for the life of me work out how to either:
a) limit the CollectionViewSource to output the first 9 items
b) limit the UniformPanel to only 3 x 3 and never to create new rows
c) limit the ItemsControl to only allow 9 data templates to be created at once.
I'm really scratching my head because I'm sure this is a common databinding scenario but I can't find anything on the web about it.
回答1:
Two solutions I can think of:
If you are using View Model, put the logic in there to create a property that you can bind to that only ever has 9 elements. Make sure it's unit tested to ensure more than 9 elements never sneak into the collection.
Alternatively you could use a converter when binding the items source to convert the full list to a reduced list of the first 9.
回答2:
This is just one of those things you can't do in XAML (yet).
You could create a "CollectionViewSourceView" (:P), which will be updated whenever CollectionViewSource is updated, to only output the first 9 items. Still, this is going into the codebehind (or better, the viewmodel).
回答3:
I was about to say the same as James Hay (use a Converter), but I would also add that you can databind a ConverterParameter in the XAML to dynamically specify how many items are returned.
来源：https://stackoverflow.com/questions/1914786/wpf-how-to-set-a-maximum-amount-of-results-from-collectionviewsource