When customizing the built-in FilteringBehavior
of the control as you mentioned all that is requires is to inherit the FilteringBehavior
class and override it's methods. Because the AsyncFilteringBehavior is a more advanced and complicated filtering behavior customizing it is not possible with a simple inheritance. In order to create custom AsyncFilteringBehavior you will need to copy the code of the behavior and only customize the item matching function which is used by it. You could customize it's parallel filtering mechanism also but it would change the way the behavior is designed to work. I created and attached a sample project which demonstrates how to create such custom AsyncFilteringBehavior. In the sample project you can change the "match" function in the FindMatchingItems
method to match your custom filtering needs.
As we see that it would be useful to be able to easily create a custom AsyncFilteringBehavior we will do our best to improve its implementation. We logged it as a feature request in our feedback portal
where you can track it's status. In the current version of RadAutoCompleteBox the only possibility of creating a custom AsyncFilteringBehavior is by using the described above approach. Hope this is helpful.
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