@DependsOn

@DependsOn([...]) names beans that must be created before this one and destroyed after it.

Why

The container already orders beans by their injected dependencies: if A takes B in its constructor, B is created first and destroyed last. You do not need @DependsOn for that.

Use it only for a dependency the container cannot see: a bean that relies on another bean's side effect without injecting it. Examples: a schema that another bean creates in the database, a global value that another bean sets up, a file that another bean writes.

Every name must exist. refresh() checks that before any bean is created.

Example

import 'package:spring_core_dart/spring_core_dart.dart';

// Creates the database tables when it starts.
@Component('schema')
class Schema {
  @PostConstruct()
  void create() {
    // CREATE TABLE ...
  }
}

// Reads the tables, but never calls Schema. Without @DependsOn the
// container could create it first.
@Component()
@DependsOn(['schema'])
class Migrations {
  @PostConstruct()
  void run() {
    // runs after the `schema` bean was created and initialized
  }
}

Parameters

In Spring (Java)

@Component
@DependsOn("schema")
class Migrations { ... }

Differences that matter: Spring takes a single name or an array; here it is always a list. A missing name fails refresh() before any bean is created.

See also

• @PostConstruct, @PreDestroy
• @Bean
• BeanRegistrar (dependsOn)