@craft-ng/core

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Service scopes ​

scope decides how many instances of a craftService exist and who has to provide it. It is the one decision to make when declaring a service.

Short version

Default to function. Move to toProvide the day a child component needs the same instance. Use global only for genuinely app-wide state.

Supported Scopes ​

global ​

  • singleton provided at root
  • ideal for app-wide services and shared state
  • no explicit provideX() helper

toProvide ​

  • requires provideX() where the service is mounted
  • useful for feature-local service trees
  • works well with tests that need explicit providers

manuallyProvidedAtRoot ​

  • explicit provider helper, but designed to be mounted at root
  • also exposes XToProvide for public provider composition
  • allows this scope to be yielded by global services, which is not possible with toProvide (it still requires explicit setup when testing with setupCraftServiceTestingByRegister).

function ​

  • creates a fresh instance on each injection
  • useful for reusable factories with bindings and inputs

abstract ​

  • declares a contract without implementation
  • exposes a requirement token to force a concrete implementation later

Recommendations For Choosing a Scope ​

  • Prefer function for a service owned by a single component. It avoids an explicit provider and makes it clear the instance is not meant to be shared with other components or child components.
  • Move to toProvide when the same instance must be shared with child components, or across several components through a common parent or route. In that case, provide it at the component boundary, a parent component, or the route.
  • Be careful with toProvide: Angular does not report a compilation error when the provider is missing, so the failure usually appears at runtime instead.
  • Use global when the instance is intentionally shared application-wide.
  • For startup-only logic that should run when the app boots but is not injected elsewhere, prefer function together with provideAppInitializer(...). If the same instance also needs to be injected by other services, use global instead.

See Also ​