When to use Provider.of<X> vs. Consumer<X> in Flutter

Question

I'm still wrapping my head around state-management techniques in flutter and am a bit confused about when and why to use Provider.of<X> vs. Consumer<X>. I understand (I think) from the documentation that when choosing between these two you would use Provider.of when we want access to the data, but you don't need the UI to change. So the following (taken from the docs) gets access to the data and updates the UI on new events:

return HumongousWidget(   // ...   child: AnotherMonstrousWidget(// <- This widget will rebuild on new data events     // ...     child: Consumer<CartModel>(       builder: (context, cart, child) {         return Text('Total price: ${cart.totalPrice}');       },     ),   ), ); 

Whereas, where we only need the data on don't want to rebuild with UI, we'd use Provider.of<X> with the listen parameter set to false, as below:

Provider.of<CartModel>(context, listen: false).add(item); \\Widget won't rebuild 

However, listen isn't required and so the following will run too:

Provider.of<CartModel>(context).add(item); \\listener optional 

So this brings me to a few questions:

1. Is this the correct way to distinguish Provider.of<X> and Consumer<X>. Former doesn't update UI, latter does?
2. If listen isn't set to false will the widget be rebuilt by default or not rebuilt? What if listen is set to true?
3. Why have Provider.of with the option to rebuild the UI at all when we have Consumer?

Answer 1

It doesn't matter. But to explain things rapidly:

Provider.of is the only way to obtain and listen to an object. Consumer, Selector, and all the *ProxyProvider calls Provider.of to work.

Provider.of vs Consumer is a matter of personal preference. But there's a few arguments for both

Provider.of

• can be called in all the widgets lifecycle, including click handlers and didChangeDependencies
• doesn't increase the indentation

Consumer

• allows more granular widgets rebuilds
• solves most BuildContext misuse

Answer 2

For your questions:

1. Is this the correct way to distinguish Provider.of<X> and Consumer<X>. Former doesn't update UI, latter does?

Provider.of<X> depends on value of listen to trigger a new State.build to widgets and State.didChangeDependencies for StatefulWidget.

Consumer<X> always update UI, as it uses Provider.of<T>(context), where listen is true. See full source here.

2. If listen isn't set to false will the widget be rebuilt by default or not rebuilt? What if listen is set to true?

Default value is true, means will trigger a new State.build to widgets and State.didChangeDependencies for StatefulWidget. See full source here.

static T of<T>(BuildContext context, {bool listen = true}).

3. Why have Provider.of with the option to rebuild the UI at all when we have Consumer?

Pretty much covered by Rémi Rousselet's answer.