I'm using Pyramid and Cornice to write some RESTful Python app and I made a simple Cornice resource
:
@resource(collection_path='/users/', path='/users/{id}')
class UsersResource(object):
def __init__(self, request):
self.request = request
@view(renderer='json', content_type=content_type)
@my_wrapper
def get(self):
return {'user_id': self.request.matchdict['id']}
As you may have noticed, along with Cornice's view
decorator, I also added an extra decorator here (my_decorator
), which I intended to use as an wrapper to add some extra information to the response:
def my_wrapper(method):
def wrapper(*args, **kw):
time_start = time()
profiler = sqltap.start()
fn_result = method(*args, **kw)
stats = profiler.collect()
time_end = time()
result = {
'info': {
'api_version': args[0].request.registry.settings.api_version,
'request_path': args[0].request.path_info,
'request_method': args[0].request.method,
'current_time': datetime.datetime.now(pytz.utc).strftime('%Y-%m-%dT%H:%M:%SZ'),
'execution_time': time_end - time_start,
'total_queries': len(stats),
'query_time': stats[0].duration if len(stats) > 0 else 0,
},
}
result.update(fn_result)
return result
return wrapper
This works fine unless I define Cornice validators
in my view
decorator:
from validators import validate_int
@resource(collection_path='/users/', path='/users/{id}')
class UsersResource(object):
def __init__(self, request):
self.request = request
@view(renderer='json', content_type=content_type, validators=validate_int) # added validators
@my_wrapper
def get(self):
return {'user_id': self.request.matchdict['id']}
validators.py
import responses
def validate_int(request):
should_be_int = request.matchdict['id']
try:
int(should_be_int)
except:
raise responses._400('This doesn\'t look like a valid ID.')
responses.py
class _400(exc.HTTPError):
def __init__(self, desc):
body = {'status': 400, 'message': 'Bad Request', 'description': desc}
Response.__init__(self, json.dumps(body))
With a code like this, my_wrapper
wraps a response only if the validation passes (which is completely understandable), but I wonder how can I still wrap the response with some extra information when the default HTTPException
is raised (because in that case the code never reaches my_wrapper
at all)?
In a short discussion with a brilliant Pyramid IRC community, I decided to do this with Pyramid's tweens, rather than using the wrapper.