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Scopes in Koin Annotations

While using definitions and modules, you may need to define scopes for particular space and time resolution.

Defining a Scope with @Scope​

Koin allows to use scopes, please refer to Koin Scopes section for more details on basics.

To declare a scope with annotations, just use @Scope annotation on a class, like this

@Scope
class MyScopeClass

this will be equivalent of the following scope section:

scope<MyScopeClass> {

}

Else, if you need rather a scope name more than a type, you need to tag a class with @Scope(name = ) annotation, using name parameter:

@Scope(name = "my_scope_name")
class MyScopeClass

this will be the equivalent of 

scope<named("my_scope_name")> {

}

Adding a definition in a Scope with @Scoped​

To declare a definition inside a scope (defined or not with annotations), just tag a class with @Scope and @Scoped annotations:

@Scope(name = "my_scope_name")
@Scoped
class MyScopedComponent

This will generate the right definition inside the scope section:

scope<named("my_scope_name")> {
  scoped { MyScopedComponent() }
}
info

You need both annotations, to indicate the needed scope space (with @Scope) and the kind of component to define (with @Scoped)

Dependency resolution from a scope​

From a scoped definition, you can resolve any definition from your inner Scope and from the parents scopes.

For example, the following case will work:

@Single
class MySingle

@Scope(name = "my_scope_name")
@Scoped
class MyScopedComponent(
  val mySingle : MySingle,
  val myOtherScopedComponent :MyOtherScopedComponent
)

@Scope(name = "my_scope_name")
@Scoped
class MyOtherScopedComponent(
  val mySingle : MySingle
)

The component MySingle is defined as single definition, in root. MyScopedComponent and MyOtherScopedComponent are defined in scope "my_scope_name". The dependencies resolution from MyScopedComponent is accessing Koin root with MySingle instance, and MyOtherScopedComponent scoped instance from current "my_scope_name" scope.

Resolving outside a Scope with @ScopeId (since 1.3.0)​

You may need to resolve a component from another scope, that is not directly accessible to your scope. For this you need to tag your dependency with @ScopeId annotation, to tell Koin to find this dependency in a scope of given scope Id.

@Factory
class MyFactory(
  @ScopeId("my_scope_id") val myScopedComponent :MyScopedComponent
)

The above code is equivalent to generated:

factory { Myfactory(getScope("my_scope_id").get()) }

This example show that MyFactory component will resolve MyScopedComponent component from a scope instance with id "my_scope_id". This scope created with id "my_scope_id" needs to be created with the right scope definition.

info

The MyScopedComponent component needs to be defined in a Scope section, and scope instance needs to created with id "my_scope_id".