[BUG] Java RestTemplate client using application/problem+json for its Accept header
Created by: ajeans
Bug Report Checklist
-
Have you provided a full/minimal spec to reproduce the issue? -
Have you validated the input using an OpenAPI validator (example)? -
What's the version of OpenAPI Generator used? -
Have you search for related issues/PRs? -
What's the actual output vs expected output? -
[Optional] Bounty to sponsor the fix (example)
Description
So we have created a REST server based on standard spring framework conventions (RestController), the openapi spec is generated using springdoc-openapi from the server, and I managed to use the gradle openapi-generator plugin to create a "java/resttemplate" client.
This is with the 4.3.1 openapi-generator plugin.
Using an integration test, this worked fine so
But then we decided to make the server handle errors as described in RFC-7807 https://tools.ietf.org/html/rfc7807 As soon as I regenerated the openapi spec and the client from it, the test started failing.
Debugging this a bit, it seems that:
- Adding the RFC-7807 for the error cases is properly reflected in the openapi spec, HTTP 200 declares a application/json content whereas HTTP 500 declares a application/problem+json content
"paths": {
"/": {
"get": {
"tags": [
"home-controller"
],
"summary": "Request information from the application",
"operationId": "home",
"responses": {
"500": {
"description": "Internal Server Error",
"content": {
"application/problem+json": {
"schema": {
"$ref": "#/components/schemas/ErrorDto"
}
}
}
},
"200": {
"description": "OK",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/HomeResponseDto"
}
}
}
}
}
}
}
}- The client is properly generated using the gradle plugin, the main change is that each *ControllerApi now knows that it should accept the two media types
final MultiValueMap<String, String> cookieParams = new LinkedMultiValueMap<String, String>();
final MultiValueMap formParams = new LinkedMultiValueMap();
- final String[] accepts = {"application/json"};
+ final String[] accepts = {"application/problem+json", "application/json"};
final List<MediaType> accept = apiClient.selectHeaderAccept(accepts);
final String[] contentTypes = {};
final MediaType contentType = apiClient.selectHeaderContentType(contentTypes);- When launching the integration test however, what happens is that
apiClient.selectHeaderAccepttransforms{"application/problem+json", "application/json"}into a singleMediaType.APPLICATION_PROBLEM_JSONbecause of its generated implementation.
As application/problem+json comes first, isJsonMime returns true and this is the only media type that is returned.
public List<MediaType> selectHeaderAccept(String[] accepts) {
if (accepts.length == 0) {
return null;
}
for (String accept : accepts) {
MediaType mediaType = MediaType.parseMediaType(accept);
if (isJsonMime(mediaType)) {
return Collections.singletonList(mediaType);
}
}
return MediaType.parseMediaTypes(StringUtils.arrayToCommaDelimitedString(accepts));
}- The client sends an HTTP Header
Accept: application/problem+jsonwhich is rejected by the server as being an unexpected media type.
org.springframework.web.client.HttpClientErrorException$UnsupportedMediaType: 415 : [{"detail":"Accept type 'application/problem+json' not supported","exception-id":"2a0da9ab-7286-4e1c-ba18-d2c2ada028b3","status":415,"timestamp":"2020-08-05T07:18:16.138179Z","title":"Unsupported Media Type"}] at org.springframework.web.client.HttpClientErrorException.create(HttpClientErrorException.java:133)
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:184)
at org.springframework.web.client.DefaultResponseErrorHandler.handleError(DefaultResponseErrorHandler.java:125)
at org.springframework.web.client.ResponseErrorHandler.handleError(ResponseErrorHandler.java:63)
at org.springframework.web.client.RestTemplate.handleResponse(RestTemplate.java:782)
at org.springframework.web.client.RestTemplate.doExecute(RestTemplate.java:740)
at org.springframework.web.client.RestTemplate.exchange(RestTemplate.java:651)openapi-generator version
This is with 4.3.1. I didn't test the 5.0.0 beta as the mustache template has the same selectHeaderAccept implementation (cf. https://github.com/OpenAPITools/openapi-generator/blob/master/modules/openapi-generator/src/main/resources/Java/libraries/resttemplate/ApiClient.mustache)
OpenAPI declaration file content or url
{
"openapi": "3.0.1",
"info": {
"title": "Example",
"description": "Example for JSON and problem JSON (RFC-7807)",
"license": {
"name": "Proprietary"
},
"version": "0.1.0-SNAPSHOT"
},
"servers": [
{
"url": "https://example.com/foo/v0",
"description": "Generated server url"
}
],
"paths": {
"/": {
"get": {
"tags": [
"home-controller"
],
"summary": "Request information from the application",
"operationId": "home",
"responses": {
"500": {
"description": "Internal Server Error",
"content": {
"application/problem+json": {
"schema": {
"$ref": "#/components/schemas/ErrorDto"
}
}
}
},
"200": {
"description": "OK",
"content": {
"application/json": {
"schema": {
"$ref": "#/components/schemas/HomeResponseDto"
}
}
}
}
}
}
}
},
"components": {
"schemas": {
"ErrorDto": {
"type": "object",
"properties": {
"detail": {
"type": "string"
},
"exception-id": {
"type": "string",
"format": "uuid"
},
"status": {
"type": "integer",
"format": "int32"
},
"timestamp": {
"type": "string",
"format": "date-time"
},
"title": {
"type": "string"
}
}
},
"HomeResponseDto": {
"type": "object",
"properties": {
"actuator": {
"type": "string",
"format": "url"
},
"swagger": {
"type": "string",
"format": "url"
}
}
}
}
}
}Generation Details
The gradle configuration is as follows
openApiGenerate {
// see https://github.com/OpenAPITools/openapi-generator/blob/master/docs/generators/java.md
generatorName = "java"
library = "resttemplate" // spring rest template and jackson is what we want
inputSpec = "$rootDir/$project.name/specs/sign-v3.0.yaml".toString()
outputDir = "$rootDir/$project.name"
// remove a lot of stuff that can be generated
generateApiDocumentation = false
generateApiTests = false
generateModelTests = false
generateModelDocumentation = false
// define correct groups
apiPackage = "com.quicksign.cases.worker.esig.client.api"
modelPackage = "com.quicksign.cases.worker.esig.client.model"
configOptions = [
dateLibrary: "java8", // we have the java8 date library
hideGenerationTimestamp: "true" // simpler diffs when regenerating
]
}Steps to reproduce
I can provide a simplified gradle project if necessary.
Related issues/PRs
#440 (closed) seems to be in the same group of "how do I deal with multiple mime types"
Suggest a fix
Naively, I would implement another method called isJsonProblemMime and only return early if the media type being tested is isJsonMime(mediaType) && !isJsonProblemMime(mediaType)
Happy to write a PR in that direction (or another) if that helps.