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Redis – Spring boot: Bean and dynamic Qualifiers

Considering the following spring-boot snippet:

// AppConfig.java

@Configuration
public class AppConfig {
    @Bean
    public PersonService users(ICache cache) {
        return new PersonServiceImpl(cache);
    }

  @Bean
  public ICache redis() {
        return new RedisCache();
    }

  @Bean
  public ICache memory() {
        return new MemoryCache();
    }
}

// PersonController.java

@RestController
public class PersonController { 
    @Autowired
    private PersonService users; 
      
    @Getmapping("/api/v1/person") 
    public List<PersonV1> getAllV1(){ 
      return users.getAllV1(); 
    } 
    
    @Getmapping("/api/v2/person") 
    public List<PersonV2> getAllV2(){ 
      return users.getAllV2(); 
    } 
}

I would like to configure spring to automatically wire endpoints from both v1 and v2 to the PersonService. However, for the v1 endpoint, I want to retrieve data from the PersonService using Memory cache as its backend, while for the v2 endpoint, I have to fetch data from Redis cache backend. If spring boot does not support this directly, what would be the best practice to achieve this? Can I use @Conditional for this purpose?

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2

Answers


  1. 0

    Considering you want to have both versions running you can make use of @Qualifier. This annotation can be used when there are multiple beans of the same type and you want to wire only one of them with a property.

    @Configuration
public class AppConfig {

    @Bean
    @Qualifier("memoryCachePersonService")
    public PersonService usersMemoryCache() {
        return new PersonServiceImpl(memoryCache());
    }

    @Bean
    @Qualifier("redisCachePersonService")
    public PersonService usersRedisCache() {
         return new PersonServiceImpl(redisCache());
     }

    @Bean
    public ICache redisCache() {
         return new RedisCache();
     }

    @Bean
    public ICache memoryCache() {
        return new MemoryCache();
    }
}

    And your Controller:

    @RestController
public class PersonController {

    @Autowired
    @Qualifier("memoryCachePersonService")
    private PersonService usersMemory;

    @Autowired
    @Qualifier("redisCachePersonService")
    private PersonService usersRedis;

    @GetMapping("/api/v1/person") 
    public List<PersonV1> getAllV1(){ 
        return usersMemory.getAllV1(); 
    } 
    
    @GetMapping("/api/v2/person") 
    public List<PersonV2> getAllV2(){ 
        return usersRedis.getAllV2(); 
    } 
}

    You can find more information about how @Qualifier works on Spring boot documentation

    You can even make use of @Primaryif that fits to you

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  2. 0

    If I understand your Q correctly you want to check memory cache before and then decide to use it or redis ?
    spring has :

    @ConditionalOnExpression("${[checkCacheBefore]}")

    but it is not clean usage and cause your controller messy .
    you can use strategypattern and check you condition before with additional service.

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