Thanks for letting me know. I’ve updated the blog post to include the missing code.

Bea

Unfortunately I am not an expert in Blend. There is a forum where you can ask Blend questions – there are typically people from the Blend team watching the questions and replying.

I hope you can find answers to your questions there.

Thanks,
Bea

It is the latter. The checkboxes are bound to a property on the items added to the ObservableCollection, so some checkboxes are unchecked and some are checked.

Al

Ah, yes, I understand your scenario with the dynamic properties and yes, CustomTypeDescriptor is the best solution. I added this topic to my list, so I will talk about it in a future post (not in the next one, since I have other topic requests before this one.)

I have one question about your ListView scenario. Are the CheckBoxes in the ListViewItems bound to one single property in the ObservableCollection, meaning they’re all checked or all unchecked? Or are they bound to a property on the items added to the ObservableCollection, which means some of them could be checked and others unchecked? From your description, it seems like you’re asking for the first, but I would expect the second one to be a more useful scenario.

Thanks,
Bea

I’m sorry it’s taken so long to get back to you. In a static situation, the observable collection would have a set of properties that you would then map to each column in a list view, something like Name, Age, and Height for example. And that’s great for a static view. The data I work with isn’t static. I have one list view and when the data is returned it may have one column of data or ten, depending on the call being made. My list view needs to be able to handle the additional (or lack) of columns without resorting to hard-code properties (i.e., Name, Age, etc). I mean, I could have set of properties named Column1, Column2, etc, but that’s pretty kludgy. The solution to this problem was (and I’m not sure I completely understand everything) to create some classes to generate some custom properties for a collection utilizing the TypeDescriptionProvider, CustomTypeDescriptor and PropertyDescriptor classes. This creates a dynamic, custom set of properties for the collection so I can map my collection to the each column in the list view. As far as the MultiBinding example goes, try this. Use the example in the SDK for having a checkbox on a ListViewItem (How to: Create ListViewItems with a CheckBox). Bind the list view to an observable collection and additionally bind the checkbox checked state to a boolean in the observable collection. Show us the example with xaml and code. There is a definite lack of coding examples for Binding/MultiBinding in code and a few good examples would go a long way to help and for understanding.

Thanks,
Al

Thanks for your feedback. I agree that real world apps are much more complex than the simple samples you find in my blog. But at the same time, all these samples are based on questions I received from customers that, like you, are writing big real world apps. I will be happy to write a sample that addresses the particular difficulties you are encountering while writing your app.

Replying to the scenarios you mentioned:

- I can certainly write my bindings in code in my next sample.
- Can you explain what you mean by dynamic properties in ObservableCollections? Are you using WPF’s property system?
- Anytime you want to bind to more than one source at a time, you should use MultiBinding. You can find a MultiBinding sample here. Let me know if this solves your problem.

Thanks,
Bea

I think a lot of your examples are ok, but they really aren’t how the real world works, at least for me anyway.

For example, although my data comes to me in an xml format, it gets parsed and placed into an object. My binding needs to take place in code because each call for data can have a different number of columns, which will be unknown until I receive the data. I have a requirement for textboxes in each column header to act as input for a filter. Each row needs a checkbox that not only is bound to the ListViewItem’s IsSelected property but also bound to the data source. And on top of all of this is a very complex architecture that leaves everything loosely coupled.

So I guess what I am asking for is better examples. Show us not only how to bind with xaml, but in code as well. Show us observable collections with dynamic properties. Show us how to bind a checkbox to a ListViewItem’s IsSelected property _and_ to a property in the data source (my current problem that needs resolution).

Thanks,
Al