Recreate aiohttp.FormData objects during request retries

Fixes Rapptz#6531

discord/http.py

@@ -131,7 +131,7 @@ async def ws_connect(self, url, *, compress=0):
 
         return await self.__session.ws_connect(url, **kwargs)
 
-    async def request(self, route, *, files=None, **kwargs):
+    async def request(self, route, *, files=None, form=None, **kwargs):
         bucket = route.bucket
         method = route.method
         url = route.url
@@ -181,6 +181,13 @@ async def request(self, route, *, files=None, **kwargs):
                 if files:
                     for f in files:
                         f.reset(seek=tries)
+
+                if form:
+                    form_data = aiohttp.FormData()
+                    for params in form:
+                        form_data.add_field(**params)
+                    kwargs['data'] = form_data
+
                 try:
                     async with self.__session.request(method, url, **kwargs) as r:
                         log.debug('%s %s with %s has returned %s', method, url, kwargs.get('data'), r.status)
@@ -371,7 +378,7 @@ def send_typing(self, channel_id):
 
     def send_files(self, channel_id, *, files, content=None, tts=False, embed=None, nonce=None, allowed_mentions=None, message_reference=None):
         r = Route('POST', '/channels/{channel_id}/messages', channel_id=channel_id)
-        form = aiohttp.FormData()
+        form = []
 
         payload = {'tts': tts}
         if content:
@@ -385,15 +392,25 @@ def send_files(self, channel_id, *, files, content=None, tts=False, embed=None,
         if message_reference:
             payload['message_reference'] = message_reference
 
-        form.add_field('payload_json', utils.to_json(payload))
+        form.append({'name': 'payload_json', 'value': utils.to_json(payload)})
         if len(files) == 1:
             file = files[0]
-            form.add_field('file', file.fp, filename=file.filename, content_type='application/octet-stream')
+            form.append({
+                'name': 'file',
+                'value': file.fp,
+                'filename': file.filename,
+                'content_type': 'application/octet-stream'
+            })
         else:
             for index, file in enumerate(files):
-                form.add_field('file%s' % index, file.fp, filename=file.filename, content_type='application/octet-stream')
-
-        return self.request(r, data=form, files=files)
+                form.append({
+                    'name': 'file%s' % index,
+                    'value': file.fp,
+                    'filename': file.filename,
+                    'content_type': 'application/octet-stream'
+                })
+
+        return self.request(r, form=form, files=files)
 
     async def ack_message(self, channel_id, message_id):
         r = Route('POST', '/channels/{channel_id}/messages/{message_id}/ack', channel_id=channel_id, message_id=message_id)

discord/webhook.py

@@ -203,20 +203,21 @@ async def request(self, verb, url, payload=None, multipart=None, *, files=None,
         if reason:
             headers['X-Audit-Log-Reason'] = _uriquote(reason, safe='/ ')
 
-        if multipart:
-            data = aiohttp.FormData()
-            for key, value in multipart.items():
-                if key.startswith('file'):
-                    data.add_field(key, value[1], filename=value[0], content_type=value[2])
-                else:
-                    data.add_field(key, value)
 
         base_url = url.replace(self._request_url, '/') or '/'
         _id = self._webhook_id
         for tries in range(5):
             for file in files:
                 file.reset(seek=tries)
 
+            if multipart:
+                data = aiohttp.FormData()
+                for key, value in multipart.items():
+                    if key.startswith('file'):
+                        data.add_field(key, value[1], filename=value[0], content_type=value[2])
+                    else:
+                        data.add_field(key, value)
+
             async with self.session.request(verb, url, headers=headers, data=data) as r:
                 log.debug('Webhook ID %s with %s %s has returned status code %s', _id, verb, base_url, r.status)
                 # Coerce empty strings to return None for hygiene purposes