dependencies property

Iterable<ProviderOrFamily>? dependencies

The list of providers that this provider potentially depends on.

Specifying this list is strictly equivalent to saying "This provider may be scoped". If a provider is scoped, it should specify dependencies. If it is never scoped, it should not specify dependencies.

The content of dependencies should be a list of all the providers that this provider may depend on which can be scoped.

For example, consider the following providers:

// By not specifying "dependencies", we are saying that this provider is never scoped
final rootProvider = Provider((ref) => Foo());
// By specifying "dependencies" (even if the list is empty),
// we are saying that this provider is potentially scoped
final scopedProvider = Provider((ref) => Foo(), dependencies: []);

Then if we were to depend on rootProvider in a scoped provider, we could write any of:

final dependentProvider = Provider((ref) {
  ref.watch(rootProvider);
  // This provider does not depend on any scoped provider,
  // as such "dependencies" is optional
});

final dependentProvider = Provider((ref) {
  ref.watch(rootProvider);
  // This provider decided to specify "dependencies" anyway, marking
  // "dependentProvider" as possibly scoped.
  // Since "rootProvider" is never scoped, it doesn't need to be included
  // in "dependencies".
}, dependencies: []);

final dependentProvider = Provider((ref) {
  ref.watch(rootProvider);
  // Including "rootProvider" in "dependencies" is fine too, even though
  // it is not required. It is a no-op.
}, dependencies: [rootProvider]);

However, if we were to depend on scopedProvider then our only choice is:

final dependentProvider = Provider((ref) {
  ref.watch(scopedProvider);
  // Since "scopedProvider" specifies "dependencies", any provider that
  // depends on it must also specify "dependencies" and include "scopedProvider".
}, dependencies: [scopedProvider]);

In that scenario, the dependencies parameter is required and it must include scopedProvider.

See also:

• provider_dependencies and scoped_providers_should_specify_dependencies.
  These are lint rules that will warn about incorrect dependencies usages.

Implementation

final Iterable<ProviderOrFamily>? dependencies;