Elegant way to prevent circular events in MVC?

Question

The question, in brief:

In MVC, how do you distinguish between a checkbox click (or a selectbox or listbox change) from a human meaning \"Controller

Answer 1

Just to recap the MVC model. Views should generally update themselves. Here's how it works: a controller changes the state of the model, the model sends updates to its views, the views pull in new state from the model and update themselves. While controllers and views are generally bundled (i.e. drilling down on data in a graphic representation) they should never interact directly, only through the model. This in general of course.

So the JS functions that update your views are not actually controllers, which is an important distinction. They should be considered part of your view. This might not be helpful to the problem at hand but I thought it merited pointing out.

You can also not delete your model, I assume you mean you're deleting someting from your model, since no views or controllers can actually exist (or be in a functional state) if they're not backed by a model.

Not being a JS code jockey and not having used gmaps I don't really see where the problem is. Does changing the state of a checkbox(checked property) fire the onClick() event? It really shouldn't IMHO but perhaps they implemented it that way, otherwise you could just attach your controller to the onClick() and add some logic to the checkbox (or, this being JS, in a function somewhere) to change the checkbox state. If that's not possible, option 1 and 2 are definitely your best bet.

addition: user interacting with a view

So what happens when a user wants to interact with a view? Frequently a widget will include both a view and the controller. A checkbox has a view (you can see if it's checked or not) and also a controller (you can click it). When you click the checkbox, in principle the following should happen:

• checkbox controller receives the event
• checkbox controller changes the state for the value this checkbox represents in the model
• model updates listeners (including the checkbox)
• checkbox updates its look to reflect that that value has changed

The first step, how the controller receives the event is somewhat language dependent, but in OOP languages it's likely a listener object attached to user interface events on this particular widget which either is the controller or notifies the controller of the user interaction.