Configuration properties for a map

Question

I have the following structure in my spring boot yaml file:

countryConfiguration:
  NL:
    address:
      postcodeKeyboardType: ALPHANUMERIC
      postcodeExample: 1111 AA
      cityExample: Amsterdam
  ES:
    address:
      postcodeKeyboardType: NUMERIC
      postcodeExample: 11111
      cityExample: Madrid

And I want to create a configuration properties class to access to those values. I have something like this:

@Configuration
@ConfigurationProperties
@Validated
public class CountryConfigurationProperties {

    @NotNull
    private Map<String, Configuration> countryConfiguration;

    public Map<String, Configuration> getCountryConfiguration() {
        return countryConfiguration;
    }

    public void setCountryConfiguration(Map<String, Configuration> 
countryConfiguration) {
        this.countryConfiguration = countryConfiguration;
    }

    public static class Configuration {
        private Object address;

        public Object getAddress() {
            return address;
        }

        public void setAddress(Object address) {
            this.address = address;
        }
    }


}

But it does not work, I get this: Binding to target org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under '' to io.bux.onboarding.application.config.CountryConfigurationProperties$$EnhancerBySpringCGLIB$$1d9a5856 failed:

Property: .countryConfiguration
Value: null
Reason: must not be null

If I remove the static inner class Configuration, and I put Object, it works...

Answer 1

I noticed that the address field has type Object. I would expect this to be of type Address and for there to be an inner class that represents the Address object.

In the code snippet below I have added an Address class to match the yml config you are using. I have tested this and it starts up successfully and maps the properties accordingly.

@Validated
@Component
@ConfigurationProperties
public class CountryConfigurationProperties {

    @NotNull
    private Map<String, Configuration> countryConfiguration;

    public Map<String, Configuration> getCountryConfiguration() {
        return countryConfiguration;
    }

    public void setCountryConfiguration(Map<String, Configuration> countryConfiguration) {
        this.countryConfiguration = countryConfiguration;
    }

    public static class Configuration {
        private Address address;

        public Address getAddress() {
            return address;
        }

        public void setAddress(Address address) {
            this.address = address;
        }
    }

    public static class Address {
        private String postcodeKeyboardType;
        private String postcodeExample;
        private String cityExample;

        public String getPostcodeKeyboardType() {
            return postcodeKeyboardType;
        }

        public void setPostcodeKeyboardType(String postcodeKeyboardType) {
            this.postcodeKeyboardType = postcodeKeyboardType;
        }

        public String getPostcodeExample() {
            return postcodeExample;
        }

        public void setPostcodeExample(String postcodeExample) {
            this.postcodeExample = postcodeExample;
        }

        public String getCityExample() {
            return cityExample;
        }

        public void setCityExample(String cityExample) {
            this.cityExample = cityExample;
        }
    }


}