sentimentAPI.py

#!/usr/bin/python

import sys
import falcon
import logging
import json
import os
import time
from datetime import datetime
from Sentiment import Sentiment

#Main Class
class SentimentAPI(Sentiment):

	def __init__(self):
		Sentiment.__init__(self, testMode = False)

	'''
	method for limiting request size
	'''
	def max_body(limit):

		def hook(req, resp, resource, params):
			length = req.content_length
			if length is not None and length > limit:
				msg = ('The size of the request is too large. The body must not '
					'exceed ' + str(limit) + ' bytes in length.')

				raise falcon.HTTPRequestEntityTooLarge(
					'Request body is too large', msg)
		return hook

	'''
	Handles POST requests
	'''
	@falcon.before(max_body(64 * 1024))
	def on_post(self, req, resp):
		try:
			text = req.context['doc']['text']
			resp.body = json.dumps(self.classify(text))

		except Exception as ex:
			self.logger(repr(ex))

			raise falcon.HTTPServiceUnavailable(
				'Error',
				'Service error, try again later',
				30)

		resp.status = falcon.HTTP_200  # This is the default status
		resp.set_header('X-Powered-By', 'sentimentAPI')


'''
Error handle
'''
class ErrorHandler(Exception):
	@staticmethod
	def handle(ex, req, resp, params):
		raise falcon.HTTPError(falcon.HTTP_725,
			'Error',
			repr(ex))


'''
forces json
'''
class RequireJSON(object):

	def process_request(self, req, resp):
		if not req.client_accepts_json:
			raise falcon.HTTPNotAcceptable('This API only supports responses encoded as JSON.')


'''
early processor makes sure the data we get from client is valid 
and json with all fields before sent to post accepter
'''
class JSONTranslator(object):

	def process_request(self, req, resp):
		if req.content_length in (None, 0):
			# Nothing to do
			return

		body = req.stream.read()
		if not body:
			raise falcon.HTTPBadRequest('Empty request body',
				'A valid JSON document is required.')

		try:
			req.context['doc'] = json.loads(body.decode('utf-8'))

		except (ValueError, UnicodeDecodeError):
			raise falcon.HTTPError(falcon.HTTP_753,
				'Malformed JSON',
				'Could not decode the request body. The '
				'JSON was incorrect or not encoded as '
				'UTF-8.')

		# did they pass text var
		if 'text' not in req.context['doc']:
			raise falcon.HTTPBadRequest(
				'Error',
				'Missing json var text, come on you had one var to pass')

		# did they pass an empty text var
		if not req.context['doc']['text']:
			raise falcon.HTTPBadRequest(
				'Error',
				'Missing empty var text, come on you had one var to pass')

	def process_response(self, req, resp, resource):
		if 'result' not in req.context:
			return

		resp.body = json.dumps(req.context['result'])


# falcon.API instance
app = falcon.API(middleware=[
	RequireJSON(),
	JSONTranslator(),
])

app.add_error_handler(ErrorHandler, ErrorHandler.handle)

# long-lived class instances
sentimentAPI = SentimentAPI()

# handle requests at /api/sentiment/v1
app.add_route('/api/sentiment/v1', sentimentAPI)