Created methods to append and finish body content on Request (#1379)

* created methods to append and finish body content on request.py so the underlying body instance can have certain flexibility; modified server.py to reflect these changes

* - made some adjustments (including the Request.body_init method) as requested by @ahopkins;
- created a new test with a custom Request class implementation of the flexibility provided by the new methods;

sanic/request.py

@@ -85,7 +85,7 @@ class Request(dict):
         self.transport = transport
 
         # Init but do not inhale
-        self.body = []
+        self.body_init()
         self.parsed_json = None
         self.parsed_form = None
         self.parsed_files = None
@@ -106,6 +106,15 @@ class Request(dict):
             return True
         return False
 
+    def body_init(self):
+        self.body = []
+
+    def body_push(self, data):
+        self.body.append(data)
+
+    def body_finish(self):
+        self.body = b"".join(self.body)
+
     @property
     def json(self):
         if self.parsed_json is None:

sanic/server.py

@@ -300,7 +300,7 @@ class HttpProtocol(asyncio.Protocol):
                 self.request.stream.put(body)
             )
             return
-        self.request.body.append(body)
+        self.request.body_push(body)
 
     def on_message_complete(self):
         # Entire request (headers and whole body) is received.
@@ -313,7 +313,7 @@ class HttpProtocol(asyncio.Protocol):
                 self.request.stream.put(None)
             )
             return
-        self.request.body = b"".join(self.request.body)
+        self.request.body_finish()
         self.execute_request_handler()
 
     def execute_request_handler(self):