Create Map with List from application YML in Spring Boot using @Value

Question

I'm trying to create a Map<Integer,List<Integer>> variable into Java service.

I have this .yml:

my:
  data:
    '{
      1:[1,2,3],
      2:[1,2,3]
    }'

And into Java code:

@Value("#{${my.data}}")
protected Map<Integer,List<Integer>> bar;

But it fails when I run the project.

Actually the error thrown is something like:

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'controller' defined in file ...

But it has to be by dependency injection, it fails when create the @Value in the @Service and the error is propagated. Also I have tested these values

my:
  data:
    '{
      1:
      - 1
      - 2,
      2:
      - 1
    }'

And it creates a lists with values -3 and -1.

| key | value |
+-----+-------+
|  1  |  [-3] |
|  2  |  [-1] |
+-----+-------+

So the error thrown before has to be due to the definition of the list in the first yml.

Also I've tested using List<Integer> and int[] into the Map object.

So, what's the correct syntax to create Map<Integer, List<Integer>>? I assumed it was like a JSON object { key: [v1, v2] } but it seems to fails.

Thanks in advance.

Are you aware that you are giving your data as single string and evaluate it as Spring Expression, whose syntax is nowhere near JSON/YAML? Is this on purpose? — flyx, Nov 16 '21 at 16:44
In general, complex values should be loaded via `@ConfigurationProperties` and it is unclear why you give the hard requirement of doing it via `@Value`. Would you drop that requirement, [this question](https://stackoverflow.com/q/24917194/347964) would give you multiple answers for different use-cases. — flyx, Nov 16 '21 at 16:54
I have used this way (created JSON as a string) because an answer in the same link you provide ([here](https://stackoverflow.com/a/65762810/13464279)). If there is another way using `@Value` please tell me. Also use `@Value` instead of `@ConfigurationProperties` is for simplicity. — J.F., Nov 16 '21 at 18:05

xerx593 · Answer 1 · 2021-11-16T19:40:48.143

With @Value annotation:

You should not map (yaml or properties "map") keys to Integer, prefer String.
(Problem) Nesting Lists...

..still, I am quite sure it is possible with (crazy SpEL(l) @Value).

baeldung-article

But Type-safe Configuration Properties produce nice results quickly:

App.java:

@SpringBootApplication
@ConfigurationPropertiesScan
public class App {

  public static void main(String[] args) {
    SpringApplication.run(App.class, args);
  }

  @Bean
  CommandLineRunner runner(@Autowired My bar) {
    return args ->  System.out.println(bar);
  }
}

My.java:

@ConfigurationProperties("my")
public class My {
    private Map<Integer, List<Integer>> data = new HashMap<>();
    // Getter + Setter!!!
}

With this "fixed" yaml:

my:
  data: {
    1: [1,2,3],
    2: [1,2,3]
  }

Prints:

My(data={1=[1, 2, 3], 2=[1, 2, 3]})

EDIT:

The "best", I got with @Value so far, is:

@Value("#{${other.data}}") Map<?, ?> other; // raw map!! :-)

with this yaml(-like):

other:
  data: '{
   1: ''[1,2,3]'',
   2: ''[1,2,3]''
  }'

Prints:

{1=[1,2,3], 2=[1,2,3]}

(jdk:8, maven:3.8.2, spring-boot:2.5.6)

Thanks, I've tested the link but it fails to create a list... I don't know if it is possible to do it using `@Value`. Also the other way provided works, thanks for the answer but I hope there is a possible way to do it with `@Value`. — J.F., Nov 16 '21 at 18:08

Create Map with List from application YML in Spring Boot using @Value

1 Answers1