[java-client] String response body sent as 'application/json'

[jmini]

While I was working on a test suite for the java clients (I will post my results in #689)

I have noticed that if the server sends a response with Content-Type application/json and following body:

"Hello world"

It gets wrongly de-serialized by the JaxRS based java clients:
expected:<"[Hello world]"> but was:<"\"Hello world\"">

The default java-client (using okhttp and gson) do not have the issue.

---

Only a quoted string as JSON value used to be illegal (you find a lot of posts telling this), but the newest JSON RFC 7159 says that this is now valid.
The reference website JSONLint also tells that "Hello world" is a valid JSON value.

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[jmini]

The java-client with the resttemplate library has the same problem.

[jmini]

One additional test-case, this is also a valid JSON value:

"Check the \"hello\" value"

[lyuanlai]

I am using openapi-generator 4.0.0-snapshot resttemplate to generate client-side codes. I run into error I suspect is the same root cause as this ticket. The generated code looks like

public RolePermission addRolePermission(String role, String body) throws RestClientException {
      Object postBody = body;
      ....

The endpoint accepts json, and returns json. This code got "Bad Request" from server. If I change to Object postBody = "\"" + body + "\"";, then server processes the request without problem.

Is there a quick fix?

[wing328]

4.0.0-snapshot resttemplate t

Please try the latest master to see if the issue still occurs. You can download the SNAPSHOT JAR as mentioned in the readme.

[lyuanlai]

Using 4.3.0-SNAPSHOT does not fix it, same codes generated. The part of the mustache template for the generated code has not changed in a relevant way:

public ResponseEntity<{{#returnType}}{{{returnType}}}{{/returnType}}{{^returnType}}Void{{/returnType}}> {{operationId}}WithHttpInfo({{#allParams}}{{{dataType}}} {{paramName}}{{#hasMore}}, {{/hasMore}}{{/allParams}}) throws RestClientException {
        Object postBody = {{#bodyParam}}{{paramName}}{{/bodyParam}}{{^bodyParam}}null{{/bodyParam}};

(Manually changing the codes the same way above correctly communicate with server again)

[arminzavada]

I experienced the same issue with a string bodied request.
I found, that it is because the sendBody function does not check if body is a String, in which case it should convert it to a buffer, and send that, rather then send it as a json

if (body instanceof String) { // added check
    Buffer buffer = Buffer.buffer((String) body);
    request.sendBuffer(buffer, responseHandler);
} else if (body instanceof byte[]) {
    Buffer buffer = Buffer.buffer((byte[]) body);
    request.sendBuffer(buffer, responseHandler);
} else if (body instanceof AsyncFile) {
    AsyncFile file = (AsyncFile) body;
    request.sendStream(file, responseHandler);
} else {
    request.sendJson(body, responseHandler);
}