During the creation of a recent demo Silverlight project, I tasked myself with creating a generic (re-useable) filter control that I could use to filter rows in a Silverlight DataGrid.

The control had to be lightweight, and work automatically with any object collection that the DataGrid was bound to – thus making it plug-and-play for any future uses.

I’ve created a great starting point with this, by designing a set of inter-operating classes that have the following key features.

1. The Filter control of writtem completely in Xaml, using Xaml binding syntax (good designer supprt)
2. By virtue of point 1, it is easily modified in Blend
3. The filter control works by creating Lambda/Linq Expression trees to perform filtering.
4. The filter control can ustilise the DescriptionAttribute for plug-and-play.

Here are a couple of screenshots:

1) No filtering

2) Adding a couple of filters, by clicking on the ‘Add New Filter’ button, setting the filter and clicking on ‘Apply All Filters’

As you can see, the compiled Expression tree effectively filtered the data in the main grid.

The advantages of this filter control are

1. You could package it up, and drop it into any scenario – the only thing the filter control needs to know is the Type details of the objects in the data collection.
2. You could play around with the visuals, and create a ‘FilteringDataGrid’ as a single control
3. It could be a great starting point for implementing a Microsoft Excel – like ‘Auto Filter’ grid.

The ideas are limitless, and the link below will allow you to download the project and try it out for yourself.

SimpleFilterControl.zip

Here are some Caveats

1. This is not production quality code. A lot of production-necessary engineering is missing for the sake of illustrating the approach(es) taken in as simple a way as possible.
2. This code can be freely used, but comes with no guarantees whatsoever.
3. I'm happy to hear about suggested improvements or alternative ideas, but if you have any criticisms about the quality of the code, please refer to point 1 above.

I hope those that take a look find it interesting, and I look forward to your comments.

Dean