HttpMessageNotWritableException: No converter for [...] with preset Content-Type 'null'] with OpenApi Spring generator

user_3014199 0
Viewed 24336

I am implementing the petstore API with openAPI in a (gradle) spring boot project. I generate a server with the openapi generator plugin and implement a simple request:

@Service
@RestController
public class PetApiController implements PetApi {

    @Override
    public ResponseEntity<Pet> getPetById(Long petId) {
        Pet p = new Pet();
        p.setId(0L);
        p.setName("fido");
        p.setPhotoUrls(new ArrayList<String>());
        p.setStatus(StatusEnum.AVAILABLE);
        p.setTags(new ArrayList<Tag>());
        Category c = new Category();
        c.setId(3L);
        c.setName("dummy category");
        p.setCategory(c);
        
        ResponseEntity<Pet> r = new ResponseEntity<Pet>(p, HttpStatus.OK);
        
        return r;
    }
}

The swagger-ui that I generate offers both xml and json queries for a request, but xml doesn't seem to work:

$ curl -X GET "http://localhost:8080/pet/1" -H  "accept: application/xml"; echo ""

$ curl -X GET "http://localhost:8080/pet/1" -H  "accept: application/json"; echo ""
{"id":0,"name":"fido","category":{"id":3,"name":"dummy category"},"photoUrls":[],"tags":[],"status":"available"}

I even get an error message:

2020-09-10 09:04:34.213  WARN 23958 --- [nio-8080-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.http.converter.HttpMessageNotWritableException: No converter for [class com.petstore.server.model.Pet] with preset Content-Type 'null']

However I cannot catch this exception and print the whole context, it only happens after return r

There is already a question with my exact error message: Springboot HttpMessageNotWritableException: No converter for [...] with preset Content-Type 'null'] But I still think my context is different since I generate my POJOs so I have no controll over them and I shouldn't have this problem in the first place since the plugin should generate everything fittingly.

openapi-generator spring-boot spring
5 Answers

for me a problem was in lines:

responses:
        "200":
          description: default response
          content:
            '*/*' # <---- here
              schema:

instead of '*/*' it should be 'application/json'

user_49065440

The spring generator discriminates against xml by default, see the documentation: https://openapi-generator.tech/docs/generators/spring under

Option  | Description                                       | Default
--------+---------------------------------------------------+---------
withXml | whether to include support for application/xml    | false
        | content type and include XML annotations in the   |
        | model (works with libraries that provide support  |
        | for JSON and XML)                                 |
user_30141990

You need to add support for xml format using the below dependency in your pom file:

<dependency>
    <groupId>com.fasterxml.jackson.dataformat</groupId>
    <artifactId>jackson-dataformat-xml</artifactId>
    <version>2.1.1</version>
</dependency>

Note : here version is the latest as per today.

user_10691860

According awnser by Peer, i have resolve my issue but it is different way. You need add "text/xml" to tell spring. Even though this limits your API to being JSON-based (which is fine for your needs), you’re welcome to set produces to an array of String for multiple content types. For example, to allow for XML output, you could add “text/html” to the produces attribute:

@RequestMapping(path = "your_path", produces = {"application/json", "text/xml"})

user_138107980

In my case, my class Pet didn't have a getter at all.

So I fixed the problem just by adding get methods for fields.

user_46093530
Related