:param method: http request method
        :param url: http request url
        :param query_params: query parameters in the url
        :param headers: http request headers
        :param body: request json body, for `application/json`
        :param post_params: request post parameters,
                            `application/x-www-form-urlencoded`
                            and `multipart/form-data`
        :param _preload_content: if False, the urllib3.HTTPResponse object will be returned without
                                 reading/decoding response data. Default is True.
        :param _request_timeout: timeout setting for this request. If one number provided, it will be total request
                                 timeout. It can also be a pair (tuple) of (connection, read) timeouts.

def request(self, method, url, query_params=None, headers=None,
                body=None, post_params=None, _preload_content=True, _request_timeout=None):
        """
        :param method: http request method
        :param url: http request url
        :param query_params: query parameters in the url
        :param headers: http request headers
        :param body: request json body, for `application/json`
        :param post_params: request post parameters,
                            `application/x-www-form-urlencoded`
                            and `multipart/form-data`
        :param _preload_content: if False, the urllib3.HTTPResponse object will be returned without
                                 reading/decoding response data. Default is True.
        :param _request_timeout: timeout setting for this request. If one number provided, it will be total request
                                 timeout. It can also be a pair (tuple) of (connection, read) timeouts.
        """
        method = method.upper()
        assert method in ['GET', 'HEAD', 'DELETE', 'POST', 'PUT', 'PATCH', 'OPTIONS']

        if post_params and body:
            raise ValueError(
                "body parameter cannot be used with post_params parameter."
            )

        post_params = post_params or {}
        headers = headers or {}

        timeout = None
        if _request_timeout:
            if isinstance(_request_timeout, (int, ) if PY3 else (int, long)):
                timeout = urllib3.Timeout(total=_request_timeout)
            elif isinstance(_request_timeout, tuple) and len(_request_timeout) == 2:
                timeout = urllib3.Timeout(connect=_request_timeout[0], read=_request_timeout[1])

        if 'Content-Type' not in headers:
            headers['Content-Type'] = 'application/json'

        try:
            # For `POST`, `PUT`, `PATCH`, `OPTIONS`, `DELETE`
            if method in ['POST', 'PUT', 'PATCH', 'OPTIONS', 'DELETE']:
                if query_params:
                    url += '?' + urlencode(query_params)
                if re.search('json', headers['Content-Type'], re.IGNORECASE):
                    if headers['Content-Type'] == 'application/json-patch+json':
                        if not isinstance(body, list):
                            headers['Content-Type'] = \
                                'application/strategic-merge-patch+json'
                    request_body = None
                    if body is not None:
                        request_body = json.dumps(body)
                    r = self.pool_manager.request(method, url,
                                                  body=request_body,
                                                  preload_content=_preload_content,
                                                  timeout=timeout,
                                                  headers=headers)
                elif headers['Content-Type'] == 'application/x-www-form-urlencoded':
                    r = self.pool_manager.request(method, url,
                                                  fields=post_params,
                                                  encode_multipart=False,
                                                  preload_content=_preload_content,
                                                  timeout=timeout,
                                                  headers=headers)
                elif headers['Content-Type'] == 'multipart/form-data':
                    # must del headers['Content-Type'], or the correct Content-Type
                    # which generated by urllib3 will be overwritten.
                    del headers['Content-Type']
                    r = self.pool_manager.request(method, url,
                                                  fields=post_params,
                                                  encode_multipart=True,
                                                  preload_content=_preload_content,
                                                  timeout=timeout,
                                                  headers=headers)
                # Pass a `string` parameter directly in the body to support
                # other content types than Json when `body` argument is provided
                # in serialized form
                elif isinstance(body, str):
                    request_body = body
                    r = self.pool_manager.request(method, url,
                                                  body=request_body,
                                                  preload_content=_preload_content,
                                                  timeout=timeout,
                                                  headers=headers)
                else:
                    # Cannot generate the request from given parameters
                    msg = """Cannot prepare a request message for provided arguments.
                             Please check that your arguments match declared content type."""
                    raise ApiException(status=0, reason=msg)
            # For `GET`, `HEAD`
            else:
                r = self.pool_manager.request(method, url,
                                              fields=query_params,
                                              preload_content=_preload_content,
                                              timeout=timeout,
                                              headers=headers)
        except urllib3.exceptions.SSLError as e:
            msg = "{0}\n{1}".format(type(e).__name__, str(e))
            raise ApiException(status=0, reason=msg)

        if _preload_content:
            r = RESTResponse(r)

            # In the python 3, the response.data is bytes.
            # we need to decode it to string.
            if PY3:
                r.data = r.data.decode('utf8')

            # log response body
            logger.debug("response body: %s", r.data)

        if not 200 <= r.status <= 299:
            raise ApiException(http_resp=r)

        return r