Spring-boot – springfox(swagger2) does not work with GsonHttpMessageConverterConfig

gsonspring-bootspringfoxswagger

What I am trying to build is a spring-boot (v1.2.3) application and expose my Rest API with SpringFox(swagger2) v2.0.0

my Swagger Spring config

@EnableSwagger2
@Configuration
public class SwaggerConfig {

    @Bean
    public Docket myApi() {
        return new Docket(DocumentationType.SWAGGER_2)
            .genericModelSubstitutes(DeferredResult.class)
            .useDefaultResponseMessages(false)
            .forCodeGeneration(false)
            .pathMapping("/my-prj");
    }

}

I need to use gson to convert my pojo's to json, and I do it this way:

@Configuration
public class GsonHttpMessageConverterConfig {

    @Bean
    public GsonHttpMessageConverter gsonHttpMessageConverter(Gson gson) {
        GsonHttpMessageConverter converter = new GsonHttpMessageConverter();
        converter.setGson(gson);
        return converter;
    }
}

The trouble is that if using GsonHttpMessageConverter, swagger v2 generates a wrong json:

{
"value": "{\"swagger\":\"2.0\",\"info\":{\"description\":\"Api Documentation\",\"version\":\"1.0\",\"title\":\"Api Documentation\",\"termsOfService\":\"urn:tos\",\"contact\":{\"name\":\"Contact Email\"},\"license\":{\"name\":\"Apache 2.0\",\"url\":\"http:
...

the JSON is prefixed with value and the real JSON becomes an escaped string.

here is how it should be if not using GsonHttpMessageConverter:

{
"swagger": "2.0",
"info": {
"description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a 
...

Is there a solution to create a correct swagger JSON without value and escaping?

Best Solution

solved the issue by myself:

the issue was with serializing this class:

package springfox.documentation.spring.web.json;

import com.fasterxml.jackson.annotation.JsonRawValue;
import com.fasterxml.jackson.annotation.JsonValue;

public class Json {
  private final String value;

  public Json(String value) {
    this.value = value;
  }

  @JsonValue
  @JsonRawValue
  public String value() {
    return value;
  }
}

to serialize it correct I implemented a SpringfoxJsonToGsonAdapter and added it to my gson config:

adapter:

public class SpringfoxJsonToGsonAdapter implements JsonSerializer<Json> {

    @Override
    public JsonElement serialize(Json json, Type type, JsonSerializationContext context) {
        final JsonParser parser = new JsonParser();
        return parser.parse(json.value());
    }
} 

gson config:

@Configuration
public class GsonHttpMessageConverterConfig {

    @Bean
    public GsonHttpMessageConverter gsonHttpMessageConverter() {
        GsonHttpMessageConverter converter = new GsonHttpMessageConverter();
        converter.setGson(gson());
        return converter;
    }

    private Gson gson() {
        final GsonBuilder builder = new GsonBuilder();
        builder.registerTypeAdapter(Json.class, new SpringfoxJsonToGsonAdapter());
        return builder.create();
    }
}