Fix pagination URL encoding.

APIs supporting pagination use a square bracket parameter to index the page and
the offset. The format is not correctly encoded by the urlencode method from
urllib when building the URL parameter list, since multidimensional dictionaries
are not supported.

For following example:

{'longitude': 0.1278, 'latitude': 51.5074, 'page': {'offset': 10}}

is encoded as:

longitude=0.1278&latitude=51.5074&page={offset : 10}

instead of:

longitude=0.1278&latitude=51.5074&page[offset]=10

The new private method _urlencode parses and prepares the dictionary before the
actual call to urlencode is done.

Resolves: #28

Author: alnacle

amadeus/client/request.py

@@ -112,7 +112,7 @@ def __request_for_verb(self):
 
     # Encodes the params before sending them
     def _encoded_params(self):
-        return urlencode(self.params)
+        return self._urlencode(self.params)
 
     # Builds up the full URL based on the scheme, host, path, and params
     def __full_url(self):
@@ -141,3 +141,20 @@ def __add_bearer_token_header(self):
     # Applies all the headers to the HTTP Request object
     def __apply_headers(self, http_request):
         http_request.headers = self.headers
+
+    # Helper method to prepare the parameter encoding
+    def _urlencode(self, d):
+        return urlencode(self._flatten_keys(d, '', {}))
+
+    # Flattens the hash keys, so page: { offset: 1 } becomes page[offet] = 1
+    def _flatten_keys(self, d, key, out):
+        if type(d) is not dict:
+            raise TypeError('Only dicts can be encoded')
+
+        for k in d:
+            keystr = k if not key else '[{}]'.format(k)
+            if type(d[k]) is dict:
+                self._flatten_keys(d[k], str(key) + str(keystr), out)
+            else:
+                out['{}{}'.format(key, keystr)] = d[k]
+        return out