Simple question about control widget values about scoped_model HOT 2 CLOSED

Hi @brianegan

Thanks so much, that's super useful and explained very clearly. I can see the usage in your code, and the reasoning behind storing the active selection in the model. I'm realizing now that having this stored makes a lot more sense, for instance in my app, the data entry widgets are on the home screen (including this DropdownButton), but you can pull a drawer over it and delete items from the dropdown list. In that case I'd want to what the user had selected, so I can change the selected value if that's the one to be deleted.

Appreciate you taking the time to answer my question!
All the best.

from scoped_model.

Hi @willismonroe!

I usually put that type of logic in the Model itself, with a getter/setter pair. In the Widget, I just call model.currentValue = selectedValue within the onChanged callback of a DropDownButton.

The reason I put it in the model? Generally, you'll want the selected value to affect other things in the Model as well! For example, in a Todo app, if you use a DropdownButton to filter the results, you'll want to use that Filter to limit the number of items displayed, and those items are generally contained in the Model as well. Therefore, in that case, it makes more sense to put this value in the Model rather than in a State class, so you can synchronize all that logic.

I've got an example of a PopupMenuButton that does exactly this type of thing in my Architecture Samples Repo with a PopupMenuButton, but the concepts should be basically the same:

1. The model class get / set methods: https://github.com/brianegan/flutter_architecture_samples/blob/master/example/scoped_model/lib/widgets/filter_button.dart#L25
2. Usage in the Widget: https://github.com/brianegan/flutter_architecture_samples/blob/master/example/scoped_model/lib/widgets/filter_button.dart#L20

Hope that helps! Let me know if it does, or if ya have follow up questions :)

from scoped_model.