Lazily encode data, params, files

Previously, data, params, and files were encoded and stored in
Request.__init__, and subsequently put into service during
Request.send. The problem with this approach is that hooks and auth
callables need to be aware of the eager encoding, and if they touch the
originals, make sure to update the encoded versions.

A better approach is to only encode late in the sending process. This
way, hooks and auth callables can safely make changes without fear of
the old, encoded variant overriding it.

requests/models.py

@@ -114,9 +114,9 @@ class Request(object):
             if 'HTTPS_PROXY' in os.environ:
                 self.proxies['https'] = os.environ['HTTPS_PROXY']
 
-        self.data, self._enc_data = self._encode_params(data)
-        self.params, self._enc_params = self._encode_params(params)
-        self.files, self._enc_files = self._encode_files(files)
+        self.data = data
+        self.params = params
+        self.files = files
 
         #: :class:`Response <Response>` instance, containing
         #: content and metadata of HTTP Response, once :attr:`sent <send>`.
@@ -314,19 +314,12 @@ class Request(object):
         Will successfully encode parameters when passed as a dict or a list of
         2-tuples. Order is retained if data is a list of 2-tuples but abritrary
         if parameters are supplied as a dict.
-
-        If the data supplied contains parameters, encodes each parameter in it,
-        and returns a list of tuples containing the encoded parameters, and a
-        urlencoded version of that.
-
-        Otherwise, assumes the data is already encoded appropriately, and
-        returns it twice.
         """
 
         if isinstance(data, bytes):
-            return data, data
+            return data
         if isinstance(data, str):
-            return data, data
+            return data
         elif hasattr(data, '__iter__'):
             try:
                 dict(data)
@@ -340,14 +333,14 @@ class Request(object):
                     result.append(
                         (k.encode('utf-8') if isinstance(k, str) else k,
                          v.encode('utf-8') if isinstance(v, str) else v))
-            return result, urlencode(result, doseq=True)
+            return urlencode(result, doseq=True)
         else:
-            return data, data
+            return data
 
     def _encode_files(self, files):
 
         if (not files) or isinstance(self.data, str):
-            return None, None
+            return None
 
         try:
             fields = self.data.copy()
@@ -365,7 +358,7 @@ class Request(object):
 
         (body, content_type) = encode_multipart_formdata(fields)
 
-        return files, (body, content_type)
+        return (body, content_type)
 
     @property
     def full_url(self):
@@ -406,11 +399,12 @@ class Request(object):
 
         url = (urlunparse([scheme, netloc, path, params, query, fragment]))
 
-        if self._enc_params:
+        enc_params = self._encode_params(self.params)
+        if enc_params:
             if urlparse(url).query:
-                url = '%s&%s' % (url, self._enc_params)
+                url = '%s&%s' % (url, enc_params)
             else:
-                url = '%s?%s' % (url, self._enc_params)
+                url = '%s?%s' % (url, enc_params)
 
         if self.config.get('encode_uri', True):
             url = requote_uri(url)
@@ -499,11 +493,11 @@ class Request(object):
 
         # Multi-part file uploads.
         if self.files:
-            (body, content_type) = self._enc_files
+            (body, content_type) = self._encode_files(self.files)
         else:
             if self.data:
 
-                body = self._enc_data
+                body = self._encode_params(self.data)
                 if isinstance(self.data, str):
                     content_type = None
                 else: