Spring @Qualifier not working, but @Resource does?

Question

I have the following code:

@Qualifier("dateObjectMapper")
private ObjectMapper mapper;

@Autowired
DefaultProjectTweetSearchProvider(
        Client client,
        ObjectMapper mapper) {
    this.client = client;
    this.mapper = mapper;
}

The above code is not working. I get an error message stating that the spring container cannot decide which bean to use in the constructor for ObjectMapper. If I instead place @Resource(name = "dateObjectMapper") above my mapper field, it works. Why is it working in that case? I have 2 ObjectMapper beans like so:

@Bean
ObjectMapper dateObjectMapper() {
   // ... 
}

@Bean
@Primary
ObjectMapper defaultObjectMapper() {
   // ... 
}

Add `@Qualifier("dateObjectMapper")` to method `dateObjectMapper()`. — Andreas, Jun 09 '17 at 13:59
So you have to annotate **both** the Bean name (method) and the field where that bean is referenced? — njk2015, Jun 09 '17 at 14:01
No, not a duplicate. I have `@Autowired` on my constructor, not on my field. I don't need to put `@Autowired` above my field. — njk2015, Jun 09 '17 at 14:03
That is what the documentation says: [7.9.4 Fine-tuning annotation-based autowiring with qualifiers](https://docs.spring.io/spring/docs/current/spring-framework-reference/html/beans.html#beans-autowired-annotation-qualifiers). But as it says: *For a fallback match, the bean name is considered a default qualifier value.* — Andreas, Jun 09 '17 at 14:03
Well actually, you *should* use `@Qualifier` both where bean is *defined* (`@Bean`) and where bean in *injected* (`@Autowired`). But, you're not actually using `@Qualifier` where the bean is injected, because that would be the constructor, which means that you should put the `@Qualifier` on the constructor *parameter*. — Andreas, Jun 09 '17 at 14:06
I fixed it. I didn't have to use `@Qualifier` in both places. Instead, I simply place the `@Qualifier` annotation before the `ObjectMapper` parameter in the constructor and remove it from the field. Link was good for showing an example. Thanks! — njk2015, Jun 09 '17 at 14:10

Evgeni Dimitrov · Accepted Answer · 2017-06-09T14:23:11.407

1

When you use constructor injection the @Qualifier annotation has to be on the argument.

private ObjectMapper mapper;

@Autowired
DefaultProjectTweetSearchProvider(
        Client client,
        @Qualifier("dateObjectMapper") ObjectMapper mapper) {
    this.client = client;
    this.mapper = mapper;
}

Be aware of the bean names. Your example:

@Bean
ObjectMapper dateObjectMapper() {
   // ... 
}

@Bean
@Primary
ObjectMapper defaultObjectMapper() {
   // ... 
}

Will create beans with the same names as the @Bean methods: dateObjectMapper and defaultObjectMapper.

edited Jun 09 '17 at 14:23

answered Jun 09 '17 at 14:13

Evgeni Dimitrov

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Perfect. This is exactly what worked. Thanks! – njk2015 Jun 09 '17 at 14:16

Spring @Qualifier not working, but @Resource does?

1 Answers1