Schema validation for XML responses

[ilaif]

Hey guys,
I hope it's the right repo to open an issue in, let me know if not.

I'm currently running a restify server with the swagger-restify-mw package to have my routes validated by a swagger api doc.
All was well until I needed to support XML requests/response. So I've done the following:

• Added application/xml to consumes, produces.
• Used express-xml-bodyparser parser as a middleware to parse XML for requests (with some customer formatter I added to normalize to how a js object would look like with json request) - requests part works fine.
• In response, I'm sending the response like this:

res.header('Content-Type', 'application/xml');
res.send({
    data
});
res.end();

while I have a restify formatter to transform the response into XML:

const xml2js = require('xml2js');
const XMLBuilder = new xml2js.Builder();

const app = restify.createServer({
    ...
    formatters: {
        'application/xml': (req, res, body, cb) => {
            if (!body) {
                res.setHeader('Content-Length', 0);
                return (null);
            }

            if (body instanceof Error) {
                if ((body.restCode || body.httpCode) && body.body) {
                    body = body.body;
                } else {
                    body = {
                        message: body.message
                    };
                }
            }

            if (Buffer.isBuffer(body)) {
                body = body.toString('base64');
            }

            const data = XMLBuilder.buildObject(obj);

            res.setHeader('Content-Length', Buffer.byteLength(data));
            return cb(null, data);
        }
    }
});

Since swagger-restify-mw is working with res.json(...) and not res.send(...) (Which I need for the formatter to hook), then I get the following error after the response is sent back to the client successfully:

Error: Response validation failed: failed schema validation
    at throwErrorWithCode (/Users/ilaif/git/location-notifier/node_modules/swagger-tools/lib/validators.js:121:13)
    at Object.module.exports.validateAgainstSchema (/Users/ilaif/git/location-notifier/node_modules/swagger-tools/lib/validators.js:176:7)
    at /Users/ilaif/git/location-notifier/node_modules/swagger-tools/middleware/swagger-validator.js:141:22
    at /Users/ilaif/git/location-notifier/node_modules/swagger-tools/node_modules/async/lib/async.js:356:13
    at async.forEachOf.async.eachOf (/Users/ilaif/git/location-notifier/node_modules/swagger-tools/node_modules/async/lib/async.js:233:13)
    at _asyncMap (/Users/ilaif/git/location-notifier/node_modules/swagger-tools/node_modules/async/lib/async.js:355:9)
    at Object.map (/Users/ilaif/git/location-notifier/node_modules/swagger-tools/node_modules/async/lib/async.js:337:20)
    at validateValue (/Users/ilaif/git/location-notifier/node_modules/swagger-tools/middleware/swagger-validator.js:134:11)
    at ServerResponse.res.end (/Users/ilaif/git/location-notifier/node_modules/swagger-tools/middleware/swagger-validator.js:252:9)
    at _cb (/Users/ilaif/git/location-notifier/node_modules/restify/lib/response.js:337:14)
    at ServerResponse.formatJSON (/Users/ilaif/git/location-notifier/node_modules/restify/lib/formatters/json.js:37:12)
    at ServerResponse.format (/Users/ilaif/git/location-notifier/node_modules/restify/lib/response.js:152:23)
    at ServerResponse.send (/Users/ilaif/git/location-notifier/node_modules/restify/lib/response.js:345:14)
    at Object.exports.sendResult (/Users/ilaif/git/location-notifier/src/api/libs/response.lib.js:18:9)
    at Promise.resolve.then.then.then.results (/Users/ilaif/git/location-notifier/src/api/controllers/compute.controller.js:101:22)
    at bound (domain.js:301:14)
    at runBound (domain.js:314:12)
    at tryCatcher (/Users/ilaif/git/location-notifier/node_modules/bluebird/js/release/util.js:16:23)
    at Promise._settlePromiseFromHandler (/Users/ilaif/git/location-notifier/node_modules/bluebird/js/release/promise.js:512:31)
    at Promise._settlePromise (/Users/ilaif/git/location-notifier/node_modules/bluebird/js/release/promise.js:569:18)
    at Promise._settlePromise0 (/Users/ilaif/git/location-notifier/node_modules/bluebird/js/release/promise.js:614:10)
    at Promise._settlePromises (/Users/ilaif/git/location-notifier/node_modules/bluebird/js/release/promise.js:693:18)

So, my responses aren't being validated by the swagger-tools module, and I get an annoying error in the background. Diving into the code, I see that the validation occurs, after my "xml formatter" output, and therefore, the module is trying to parse an xml text string instead of a JS object. I suppose that XML should be supported, since swagger also supports that.
What am I doing wrong? Or how can this be fixed?

My versions:
"swagger-restify-mw": "^0.1.0",
which uses:
"swagger-node-runner": "^0.7.0"

Thanks!
Ilai