[FIXED] make ConfigurationProperties optional

Issue

I have spring boot application which uses application.yml for configuration. The structure is something like:

...
rmq:
  host: "host"
  port: 5672
...

In my code I have ApplicationConfig class which looks like below:

@AllArgsConstructor
class ApplicationConfig {
  private RabbitConfig rabbitConfig;
}

@ConfigurationProperties(prefix = "rmq")
class RabbitConfig {
  @NotNull
  private String host;
  @NotNull
  private Integer port;
}

The problem is that section rmq is optional in my application. And I want field rabbitConfig will init by null in case it is absent in application.yml.

But really if I drop rmq section in config file I've got an error (rmq.host is absent). Is it possible to force springboot to init rabbitConfig with null in that case?

Solution

You can use @ConditionalOnProperty for such cases. In your case, you should define it as:

@ConfigurationProperties(prefix = "rmq")
@ConditionalOnProperty(prefix = "rmq", name = "host", matchIfMissing = true)
class RabbitConfig {
  @NotNull
  private String host;
  @NotNull
  private Integer port;
}

Then it will load the bean only if there is rmq.host set, and if not, it will be set to null.

There is also an alternative that you always put i.e. rmq.enabled = true | false, and then @ConditionalOnProperty(prefix = "rmq", name = "host", havingValue = true)

Answered By - Aid Hadzic
Answer Checked By - Marilyn (JavaFixing Volunteer)