How can I add custom json object to Openapi spec generated by SpringBoot SpringDoc?

Question

My springboot project generates openapi spec using SpringDoc. I want to add a json object to the generated spec

{
    "api-definition": {
      "priority": 1,
      "owner: "jack"
    }
}

so that the generated spec file looks like

{"openapi":"3.0.1",

  ................

  ................

  "api-definition": {
      "priority": 1,
      "owner: "jack"
  }
}

Can someone please help.

Answer 1

I was able to do this by creating an OpenApiCustomiser bean.

@Configuration
public class OpenApiConfig {

@Bean
public OpenApiCustomiser customise() {
    return openApi -> {
        try {
            openApi.setExtensions(vendorExtensions());
        } catch (JsonProcessingException e) {
            log.error("bad json, should never happen");
        }
    };
}

private static ObjectMapper mapper = new ObjectMapper();

private Map<String, Object> vendorExtensions() throws JsonProcessingException {
    MapType type = mapper.getTypeFactory().constructMapType(
            Map.class, String.class, Object.class);
    Map<String, Object> stringObjectMap = new HashMap<>();

    stringObjectMap.put("api-definition",
            mapper.readValue(readFile("api-definition.json"), type));
    return stringObjectMap;
}

//To read file from resources folder
private String readFile(String fileName) {
    ClassLoader classLoader = getClass().getClassLoader();
    try {
        return Files.readString(Path.of(classLoader.getResource(fileName).getFile()));
    } catch (IOException ex) {
        log.error(ex.getMessage());
    }
    return null;
}

}

api-definition.json looks like below

{ 
  "priority": 1,
  "owner: "jack"
}