GSON support needed

[Ziemowit]

1. Preface

In project based on Spring Boot + Spring Rest we are using GSON as message converter. We would like to add Springfox with swagger-ui to our application as it gives amazing functionality.

2. Issue

And it works when Jackson is used (we have checked it), but when GSON then swagger-ui throws an error.

We think that the reason for that is when we call "/v2/api-docs" we receive 2 different responses based on type of JSON converter used:

a) Jackson

{"swagger":"2.0","info":{"description":"Api Documentation", ...

b) GSON

{"value":{"swagger":"2.0" ...

3. Hack solution We have found lets say the "hack solution" here: http://stackoverflow.com/questions/30219946/springfoxswagger2-does-not-work-with-gsonhttpmessageconverterconfig but if possible we would like to avoid this.

4. Final request Would it be possible to add support for GSON in your application?

[dilipkrish]

Yes it would be possible but I don't have the time to do it. Would love to have an external contribution.

[cheese10yun]

I solved this problem. Import package is important

import com.google.gson.JsonElement;
import com.google.gson.JsonParser;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
import java.lang.reflect.Type;
import springfox.documentation.spring.web.json.Json;

public class SwaggerJsonSerialize implements JsonSerializer<Json> {

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

add to GsonHttpMessageConverter

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import org.springframework.http.converter.json.GsonHttpMessageConverter;
import springfox.documentation.spring.web.json.Json;

public class CustomHttpMessageConverter {

  public GsonHttpMessageConverter buildGson() {
    final Gson gson = new GsonBuilder()
        .registerTypeAdapter(Json.class, new SwaggerJsonSerialize())
        .serializeNulls()
        .create();

    final GsonHttpMessageConverter converter = new GsonHttpMessageConverter();
    converter.setGson(gson);
    return converter;
  }

}

Import the SwaggerJsonSerialized added above

Register the HttpMessageConverter (GsonHttpMessageConverter).

[dheerajsah]

We are using .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES) with naming convention of java to JSON and vice-versa on GSON like ` private GsonHttpMessageConverter customGsonHttpMessageConverter() { Gson gson = new GsonBuilder().setPrettyPrinting() .setFieldNamingPolicy(FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES) .setExclusionStrategies(new AnnotationExclusionStrategy()) .addSerializationExclusionStrategy(new AnnotationExclusionSerializationStrategy()) .addDeserializationExclusionStrategy(new AnnotationExclusionDeserializationStrategy()) .registerTypeAdapter(PipelineDeviceContainer.class, new PipelineDeviceContainerDeserializer()) .registerTypeAdapter(Date.class, new DateSerializer()) .registerTypeAdapter(Date.class, new DateDeserializer()) .registerTypeAdapter(Json.class, new SpringfoxJsonToGsonAdapter()) .serializeNulls() .create();

    GsonHttpMessageConverter gsonMessageConverter = new GsonHttpMessageConverter();
    gsonMessageConverter.setGson(gson);

    return gsonMessageConverter;
}

private static class SpringfoxJsonToGsonAdapter implements JsonSerializer<Json> { @Override public JsonElement serialize(Json json, Type type, JsonSerializationContext context) { return JsonParser.parseString(json.value()); } } ` but it seems like it always expect an FieldNamingPolicy.IDENTITY convention, hence the first page of swagger-ui/index.html works, but expanding the API throws an exception.

Any pointers or idea?