[java] Spring Boot - inject map from application.yml

I have a Spring Boot application with the following application.yml - taken basically from here:

info:
   build:
      artifact: ${project.artifactId}
      name: ${project.name}
      description: ${project.description}
      version: ${project.version}

I can inject particular values, e.g.

@Value("${info.build.artifact}") String value

I would like, however, to inject the whole map, i.e. something like this:

@Value("${info}") Map<String, Object> info

Is that (or something similar) possible? Obviously, I can load yaml directly, but was wondering if there's something already supported by Spring.

Solution for pulling Map using @Value from application.yml property coded as multiline

application.yml

other-prop: just for demo 

my-map-property-name: "{\
         key1: \"ANY String Value here\", \  
         key2: \"any number of items\" , \ 
         key3: \"Note the Last item does not have comma\" \
         }"

other-prop2: just for demo 2 

Here the value for our map property "my-map-property-name" is stored in JSON format inside a string and we have achived multiline using \ at end of line

myJavaClass.java

import org.springframework.beans.factory.annotation.Value;

public class myJavaClass {

@Value("#{${my-map-property-name}}") 
private Map<String,String> myMap;

public void someRandomMethod (){
    if(myMap.containsKey("key1")) {
            //todo...
    } }

}

More explanation

• \ in yaml it is Used to break string into multiline

• \" is escape charater for "(quote) in yaml string

• {key:value} JSON in yaml which will be converted to Map by @Value

• #{ } it is SpEL expresion and can be used in @Value to convert json int Map or Array / list Reference

Tested in a spring boot project

You can make it even simplier, if you want to avoid extra structures.

service:
  mappings:
    key1: value1
    key2: value2

@Configuration
@EnableConfigurationProperties
public class ServiceConfigurationProperties {

  @Bean
  @ConfigurationProperties(prefix = "service.mappings")
  public Map<String, String> serviceMappings() {
    return new HashMap<>();
  }

}

And then use it as usual, for example with a constructor:

public class Foo {

  private final Map<String, String> serviceMappings;

  public Foo(Map<String, String> serviceMappings) {
    this.serviceMappings = serviceMappings;
  }

}

In case of direct @Value injection, the most elegant way is writing the key-values as an inline json (use ' and " chars to avoid cumbersome escapings) and parsing it using SPEL:

#in yaml file:
my:
  map:
      is: '{ "key1":"val1", 
              "key2":"val2" }'

in your @Component or @Bean, :

@Component
public class MyClass{
     @Value("#{${my.map.is}}")
     Map<String,String> myYamlMap;
}

for a more YAML convenient syntax, you can avoid the json curly braces altogether, directly typing the key value pairs

 my:  
   map:  
       is: '"a":"b", "foo":"bar"'

and add the missing curly braces directly to your @Value SPEL expression:

@Value("#{{${my.map.is}}}")
 Map<String,String> myYamlMap;

the value will be resolved from the yaml, the wrapping curlies will be concatenated to it, and finally the SPEL expression will resolve the string as map.

Below solution is a shorthand for @Andy Wilkinson's solution, except that it doesn't have to use a separate class or on a @Bean annotated method.

application.yml:

input:
  name: raja
  age: 12
  somedata:
    abcd: 1 
    bcbd: 2
    cdbd: 3

SomeComponent.java:

@Component
@EnableConfigurationProperties
@ConfigurationProperties(prefix = "input")
class SomeComponent {

    @Value("${input.name}")
    private String name;

    @Value("${input.age}")
    private Integer age;

    private HashMap<String, Integer> somedata;

    public HashMap<String, Integer> getSomedata() {
        return somedata;
    }

    public void setSomedata(HashMap<String, Integer> somedata) {
        this.somedata = somedata;
    }

}

We can club both @Value annotation and @ConfigurationProperties, no issues. But getters and setters are important and @EnableConfigurationProperties is must to have the @ConfigurationProperties to work.

I tried this idea from groovy solution provided by @Szymon Stepniak, thought it will be useful for someone.

To retrieve map from configuration you will need configuration class. @Value annotation won't do the trick, unfortunately.

Application.yml

entries:
  map:
     key1: value1
     key2: value2

Configuration class:

@Configuration
@ConfigurationProperties("entries")
@Getter
@Setter
 public static class MyConfig {
     private Map<String, String> map;
 }

I run into the same problem today, but unfortunately Andy's solution didn't work for me. In Spring Boot 1.2.1.RELEASE it's even easier, but you have to be aware of a few things.

Here is the interesting part from my application.yml:

oauth:
  providers:
    google:
     api: org.scribe.builder.api.Google2Api
     key: api_key
     secret: api_secret
     callback: http://callback.your.host/oauth/google

providers map contains only one map entry, my goal is to provide dynamic configuration for other OAuth providers. I want to inject this map into a service that will initialize services based on the configuration provided in this yaml file. My initial implementation was:

@Service
@ConfigurationProperties(prefix = 'oauth')
class OAuth2ProvidersService implements InitializingBean {

    private Map<String, Map<String, String>> providers = [:]

    @Override
    void afterPropertiesSet() throws Exception {
       initialize()
    }

    private void initialize() {
       //....
    }
}

After starting the application, providers map in OAuth2ProvidersService was not initialized. I tried the solution suggested by Andy, but it didn't work as well. I use Groovy in that application, so I decided to remove private and let Groovy generates getter and setter. So my code looked like this:

@Service
@ConfigurationProperties(prefix = 'oauth')
class OAuth2ProvidersService implements InitializingBean {

    Map<String, Map<String, String>> providers = [:]

    @Override
    void afterPropertiesSet() throws Exception {
       initialize()
    }

    private void initialize() {
       //....
    }
}

After that small change everything worked.

Although there is one thing that might be worth mentioning. After I make it working I decided to make this field private and provide setter with straight argument type in the setter method. Unfortunately it wont work that. It causes org.springframework.beans.NotWritablePropertyException with message:

Invalid property 'providers[google]' of bean class [com.zinvoice.user.service.OAuth2ProvidersService]: Cannot access indexed value in property referenced in indexed property path 'providers[google]'; nested exception is org.springframework.beans.NotReadablePropertyException: Invalid property 'providers[google]' of bean class [com.zinvoice.user.service.OAuth2ProvidersService]: Bean property 'providers[google]' is not readable or has an invalid getter method: Does the return type of the getter match the parameter type of the setter?

Keep it in mind if you're using Groovy in your Spring Boot application.

foo.bars.one.counter=1
foo.bars.one.active=false
foo.bars[two].id=IdOfBarWithKeyTwo

public class Foo {

  private Map<String, Bar> bars = new HashMap<>();

  public Map<String, Bar> getBars() { .... }
}

https://github.com/spring-projects/spring-boot/wiki/Spring-Boot-Configuration-Binding