Template: reuse LazyResponse for rendered response

Previously, only status, headers, and content type are passed to the
final rendered response.  After this change, the LazyResponse is
preserved and only has its body changed after rendering.  This allows
for, e.g., setting cookie for the LazyResponse.

Author: Huy-Ngo

sanic_ext/extensions/templating/engine.py

@@ -42,13 +42,13 @@ def template(
         def decorator(f):
             @wraps(f)
             async def decorated_function(*args, **kwargs):
-                context = f(*args, **kwargs)
+                response = f(*args, **kwargs)
                 if isawaitable(context):
-                    context = await context
+                    response = await context
                 if isinstance(context, HTTPResponse) and not isinstance(
-                    context, TemplateResponse
+                    response, TemplateResponse
                 ):
-                    return context
+                    return response
 
                 # TODO
                 # - Allow each of these to be a callable that is executed here
@@ -57,20 +57,26 @@ async def decorated_function(*args, **kwargs):
                     "content_type": content_type,
                     "headers": headers,
                 }
+                context = {}
 
-                if isinstance(context, LazyResponse):
-                    for attr in ("status", "headers", "content_type"):
-                        value = getattr(context, attr, None)
-                        if value:
-                            params[attr] = value
-                    context = context.context
+                if isinstance(response, LazyResponse):
+                    context = response.context
+                elif isinstance(response, dict):
+                    context = response
+                    response = HTTPResponse(**params)
+                else:
+                    raise TypeError("A templated view must return a dict or HTTPResponse.")
 
                 context["request"] = Request.get_current()
 
                 content = render(**context)
                 if isawaitable(content):
                     content = await content
 
+                if isinstance(content, str):
+                    content = content.encode()
+                response.body = content
+
                 return HTTPResponse(content, **params)
 
             return decorated_function