Refactoring Bloated ViewModel
- by Holy Christ
Hi,
I am writing a PRISM/MVVM/WPF application. It's a LOB application, so there are a lot of complicated rules. I've noticed the View Model is starting to get bloated. There are two main issues.
One is that to maintain MVVM, I'm doing a lot of things that feel hacky like adding a bunch of properties to my VM. The view binds to those properties to keep track of what feels like view specific information. For example, a boolean keeping track of the status of a long running process in the VM, so the view can disable some of its controls while the long running process is working. I've read that this issue could be solved with Attached Behaviors. I'll look more into that. In the example MVVM apps you see online, this isn't a big deal because they are over-simplified.
The other issue is the number of commands in my VM. Right now there are four commands. I'm defining the commands in the VM using Josh Smith's RelayCommand (basically the DelegateCommand in PRISM) so all the business logic lives in the VM. I considered moving each command into separate unit of works. I'm not sure the best way to do this.
Which patterns are you guys using to keep your VMs clean? I can already feel someone responding with "your view and VM is too complicated, you should break them into many view/VMs". It is certainly not too complicated from a Ux perspective - there are 2 buttons, a combobox, and a listbox. Also, from a logical perspective, it is one cohesive domain. Having said that, I'm very interested in hearing how others are dealing with this type of issue.
Thanks for your input.
