Flutter NowPlaying Example Provider Error

Question

I'm struggling with some flutter code especially streamprovider.

https://pub.dev/packages/nowplaying/example

I tried this code with new flutter project but it keeps throwing errors.

Can you please help me solve this error?

Error code is like below:

══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════ The following ProviderNotFoundException was thrown building Consumer(dirty): Error: Could not find the correct Provider above this Consumer Widget

This happens because you used a BuildContext that does not include the provider of your choice. There are a few common scenarios:

• You added a new provider in your main.dart and performed a hot-reload. To fix, perform a hot-restart.

• The provider you are trying to read is in a different route.

  Providers are "scoped". So if you insert of provider inside a route, then other routes will not be able to access that provider.

• You used a BuildContext that is an ancestor of the provider you are trying to read.

  Make sure that Consumer is under your MultiProvider/Provider. This usually happens when you are creating a provider and trying to read it immediately.

  For example, instead of:

    return Provider<Example>(
      create: (_) => Example(),
      // Will throw a ProviderNotFoundError, because `context` is associated
      // to the widget that is the parent of `Provider<Example>`
      child: Text(context.watch<Example>()),
    ),   }   ```
  
  consider using `builder` like so:
  
  ```   Widget build(BuildContext context) {
    return Provider<Example>(
      create: (_) => Example(),
      // we use `builder` to obtain a new `BuildContext` that has access to the provider
      builder: (context) {
        // No longer throws
        return Text(context.watch<Example>()),
      }
    ),   }   ```
  

Answer 1

There are a few things surprising me within the example:

1. The example ommits the create: (_) => Example(), part. For this try adding: create: (_) => NowPlayingTrack(),
2. Make sure to add initialValue: null, as the provider package since version 5.0.0-nullsafety requires initialData for both FutureProvider and StreamProvider.
3. Refer to provider docs:

"To expose a newly created object, use the default constructor of a provider. Do not use the .value constructor if you want to create an object, or you may otherwise have undesired side effects"

This also means you should not use value: NowPlaying.instance.stream, to create your object but instead create a new object inside create (see 1.).

4. The example is not specifying the concrete provider type, which might cause problems. Try this: StreamProvider<NowPlayingTrack>(...)