Can't watch object instance with Riverpod

Question

In a Flutter web project, I'm having this issue with Riverpod:

Consumer(
  builder: (context, watch, child) {
    final om=watch(human);  
    return Text(om.name); }

'watch' is underlined and the compiler says: The expression doesn't evaluate to a function, so it can't be invoked. The quick fix suggestion is to remove human from the parenthesis. Of course, that's not happening while I have still have some fight left in me. This is the definition of human:

final human=ChangeNotifierProvider((ref)=>Human()); 

class Human with ChangeNotifier{String name="tananana";}

I couldn't tell you what version of Riverpod I'm importing, as I've had to leave it unspecified in pubspec.yaml so that it may work out its conflicts with the other imports, but I'm on channel master running version 2.9.0-1.0.pre.294

Any advice would be valued.

score 7 · Accepted Answer · answered Jan 09 '22 at 13:51

7

You're most likely using version 1.0.x of Riverpod, which changes the syntax for listening providers.

TL;DR, Consumer doesn't receive "watch" as parameter but a "ref". So to watch a provider, you need to do:

Consumer(
  builder: (context, ref, child) {
    final om = ref.watch(human);

See the migration guide for more informations

answered Jan 09 '22 at 13:51

Rémi Rousselet

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That did it!!! you = lifesaver – Eight Rice Jan 09 '22 at 13:58
You wouldn't happen to know how to do context.read in this version? – Eight Rice Jan 11 '22 at 14:22
@EightRice it is "ref.read" instead – Rémi Rousselet Jan 12 '22 at 12:50
There was no "ref" as far as the compiler was concerned so I ended up downgrading to the old versions. – Eight Rice Jan 12 '22 at 16:09

Can't watch object instance with Riverpod

1 Answers1