Question

I know this is probably really daft, but my head isn’t working properly today.

I have a patient entity and a disability table. A patient can have 0 or many disabilities.

If I create a ListBox whose ItemsSource is bound to an ObservableCollection of Disability how do I hook the checked/unchecked of the items CheckBox to add/remove the disability from my patients’ collection of Disabilities using MVVM? What would the CheckBox be bound to on my patient entity?

Answer 1

The CheckedListBox expects to be bound to a list of items that have a boolean property which indicates the state of each checkbox. However, your model has a collection property that you wish to add / remove items to / from based on the checkbox state.

This sounds like the job of a view model!

From your PatientViewModel expose a collection of DisabilityViewModel instances that are bound to your CheckedListBox, each DisabilityViewModel instance should have a IsChecked boolean property. Detect the changing of this state within your view model, then within PatientViewModel updated the state of the wrapped Patient model object.