Cannot inject List<String> even using @Named [SPR-13585]

[spring-projects-issues]

Alexandre Navarro opened SPR-13585 and commented

Impossible to inject a Generic type (like List<String>) to create a @Bean via an argument of the method even though with using @Named.

A full example to describe the problem:

@Configuration
public class AppConfiguration {
   
    private static final Logger LOGGER = LoggerFactory.getLogger(AppConfiguration.class);

    @Bean
    public Map<String, String> map() {
        Map<String, String> map = new HashMap<>();
        for (int i = 0; i < 10; i++) {
            map.put("" + i, "" + i);
        }
        return map;
    }
    
    
    // Does not work, inject does not work for a generic type
    // Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [java.lang.String] found for dependency [map with value type java.lang.String]: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@javax.inject.Named(value=map)}
    @Bean
    public List<String> list2( @Named("map") Map<String, String> map) {
        return new ArrayList<>(map.values());
    }
    
    // Work 
    @Resource(name = "map")
    private Map<String, String> map;
    
    
    // Work
    @Bean
    public List<String> list() {
        return new ArrayList<>(this.map.values());
    }
    
    
    
    /**
     * <p>main.</p>
     *
     * @param args
     */
    public static void main(String[] args) {

        final ApplicationContext context = 
        new AnnotationConfigApplicationContext(AppConfiguration.class);
        final Map<String, String> map = (Map<String, String>) context.getBean("map");
        LOGGER.info("map={}", map);
        final List<String> list = (List<String>) context.getBean("list");
        LOGGER.info("list={}", list);
//        final List<String> list2 = (List<String>) context.getBean("list2");
//        LOGGER.info("list2={}", list2);
    }


}

For me, it should work. Tell if I did something wrong or if it exists a work around just via annotation on arguments of a @Bean method (I don't want to use Wrapper class of a GenericType or @Resource the bean wanted in a field in the Configuration file like in the example).

---

Affects: 4.2.2

Issue Links:

• Make spring support like CDI @Produces (for Array/Map/Collection inject) [SPR-11269] #15894 Make spring support like CDI @Produces (for Array/Map/Collection inject) ("is duplicated by")
• Allow for normal bean wiring semantics for types assignable to Map [SPR-7915] #12570 Allow for normal bean wiring semantics for types assignable to Map
• @Autowired does not work for target bean of type Collection [SPR-12180] #16794 @Autowired does not work for target bean of type Collection

Referenced from: commits 4a0fa69

[spring-projects-issues]

Juergen Hoeller commented

I'm afraid this is by design, since @Named is just a qualifier that narrows the set of autowire candidates, not an override for the basic Collection/Map processing that @Autowired/@Inject implies.

That said, we are aware that this can be unintuitive for such scenarios and are considering to provide some solution for such scenarios in the 4.3 timeframe.

Juergen

[spring-projects-issues]

Alexandre Navarro commented

Thanks

[sbrannen]

If you have shown interest in this issue, you may also be interested in the following which is currently scheduled for inclusion in Spring Framework 6.1.

• Direct autowiring of existing collection subtype bean if ApplicationContext contains beans of type T #30022