提高 NotImplementedError NotImplementedError
raise NotImplementedError NotImplementedError
我使用 pycharm 使用 tornado web 框架编写了一个 python3 web 应用程序项目，
列表服务已经搭建完成。我需要构建剩余的两个组件：用户服务和 public API 层。列表服务的实现可以作为一个很好的起点，以了解更多关于如何使用 Tornado Web 框架构建 Web 应用程序的信息。
我需要使用 tornado 的内置 HTTP 请求框架。
当我尝试 运行 程序时，在收听 ( app.listen(options.port)) 时发生错误：
Traceback (most recent call last):
File "D:/Bill/python/Tornado/99-python-exercise-master/listing_service.py", line 203, in <module>
app.listen(options.port)
File "C:\Program Files\Python38\lib\site-packages\tornado\web.py", line 2116, in listen
server.listen(port, address)
File "C:\Program Files\Python38\lib\site-packages\tornado\tcpserver.py", line 152, in listen
self.add_sockets(sockets)
File "C:\Program Files\Python38\lib\site-packages\tornado\tcpserver.py", line 165, in add_sockets
self._handlers[sock.fileno()] = add_accept_handler(
File "C:\Program Files\Python38\lib\site-packages\tornado\netutil.py", line 279, in add_accept_handler
io_loop.add_handler(sock, accept_handler, IOLoop.READ)
File "C:\Program Files\Python38\lib\site-packages\tornado\platform\asyncio.py", line 100, in add_handler
self.asyncio_loop.add_reader(fd, self._handle_events, fd, IOLoop.READ)
File "C:\Program Files\Python38\lib\asyncio\events.py", line 501, in add_reader
raise NotImplementedError
NotImplementedError
代码：
import tornado.web
import tornado.log
import tornado.options
import sqlite3
import logging
import json
import time
class App(tornado.web.Application):
def __init__(self, handlers, **kwargs):
super().__init__(handlers, **kwargs)
# Initialising db connection
self.db = sqlite3.connect("listings.db")
self.db.row_factory = sqlite3.Row
self.init_db()
def init_db(self):
cursor = self.db.cursor()
# Create table
cursor.execute(
"CREATE TABLE IF NOT EXISTS 'listings' ("
+ "id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,"
+ "user_id INTEGER NOT NULL,"
+ "listing_type TEXT NOT NULL,"
+ "price INTEGER NOT NULL,"
+ "created_at INTEGER NOT NULL,"
+ "updated_at INTEGER NOT NULL"
+ ");"
)
self.db.commit()
class BaseHandler(tornado.web.RequestHandler):
def write_json(self, obj, status_code=200):
self.set_header("Content-Type", "application/json")
self.set_status(status_code)
self.write(json.dumps(obj))
# /listings
class ListingsHandler(BaseHandler):
@tornado.gen.coroutine
def get(self):
# Parsing pagination params
page_num = self.get_argument("page_num", 1)
page_size = self.get_argument("page_size", 10)
try:
page_num = int(page_num)
except:
logging.exception("Error while parsing page_num: {}".format(page_num))
self.write_json({"result": False, "errors": "invalid page_num"}, status_code=400)
return
try:
page_size = int(page_size)
except:
logging.exception("Error while parsing page_size: {}".format(page_size))
self.write_json({"result": False, "errors": "invalid page_size"}, status_code=400)
return
# Parsing user_id param
user_id = self.get_argument("user_id", None)
if user_id is not None:
try:
user_id = int(user_id)
except:
self.write_json({"result": False, "errors": "invalid user_id"}, status_code=400)
return
# Building select statement
select_stmt = "SELECT * FROM listings"
# Adding user_id filter clause if param is specified
if user_id is not None:
select_stmt += " WHERE user_id=?"
# Order by and pagination
limit = page_size
offset = (page_num - 1) * page_size
select_stmt += " ORDER BY created_at DESC LIMIT ? OFFSET ?"
# Fetching listings from db
if user_id is not None:
args = (user_id, limit, offset)
else:
args = (limit, offset)
cursor = self.application.db.cursor()
results = cursor.execute(select_stmt, args)
listings = []
for row in results:
fields = ["id", "user_id", "listing_type", "price", "created_at", "updated_at"]
listing = {
field: row[field] for field in fields
}
listings.append(listing)
self.write_json({"result": True, "listings": listings})
@tornado.gen.coroutine
def post(self):
# Collecting required params
user_id = self.get_argument("user_id")
listing_type = self.get_argument("listing_type")
price = self.get_argument("price")
# Validating inputs
errors = []
user_id_val = self._validate_user_id(user_id, errors)
listing_type_val = self._validate_listing_type(listing_type, errors)
price_val = self._validate_price(price, errors)
time_now = int(time.time() * 1e6) # Converting current time to microseconds
# End if we have any validation errors
if len(errors) > 0:
self.write_json({"result": False, "errors": errors}, status_code=400)
return
# Proceed to store the listing in our db
cursor = self.application.db.cursor()
cursor.execute(
"INSERT INTO 'listings' "
+ "('user_id', 'listing_type', 'price', 'created_at', 'updated_at') "
+ "VALUES (?, ?, ?, ?, ?)",
(user_id_val, listing_type_val, price_val, time_now, time_now)
)
self.application.db.commit()
# Error out if we fail to retrieve the newly created listing
if cursor.lastrowid is None:
self.write_json({"result": False, "errors": ["Error while adding listing to db"]}, status_code=500)
return
listing = dict(
id=cursor.lastrowid,
user_id=user_id_val,
listing_type=listing_type_val,
price=price_val,
created_at=time_now,
updated_at=time_now
)
self.write_json({"result": True, "listing": listing})
def _validate_user_id(self, user_id, errors):
try:
user_id = int(user_id)
return user_id
except Exception as e:
logging.exception("Error while converting user_id to int: {}".format(user_id))
errors.append("invalid user_id")
return None
def _validate_listing_type(self, listing_type, errors):
if listing_type not in {"rent", "sale"}:
errors.append("invalid listing_type. Supported values: 'rent', 'sale'")
return None
else:
return listing_type
def _validate_price(self, price, errors):
# Convert string to int
try:
price = int(price)
except Exception as e:
logging.exception("Error while converting price to int: {}".format(price))
errors.append("invalid price. Must be an integer")
return None
if price < 1:
errors.append("price must be greater than 0")
return None
else:
return price
# /listings/ping
class PingHandler(tornado.web.RequestHandler):
@tornado.gen.coroutine
def get(self):
self.write("pong!")
def make_app(options):
return App([
(r"/listings/ping", PingHandler),
(r"/listings", ListingsHandler),
], debug=options.debug)
if __name__ == "__main__":
# Define settings/options for the web app
# Specify the port number to start the web app on (default value is port 6000)
tornado.options.define("port", default=6000)
# Specify whether the app should run in debug mode
# Debug mode restarts the app automatically on file changes
tornado.options.define("debug", default=True)
# Read settings/options from command line
tornado.options.parse_command_line()
# Access the settings defined
options = tornado.options.options
# Create web app
app = make_app(options)
app.listen(options.port)
logging.info("Starting listing service. PORT: {}, DEBUG: {}".format(options.port, options.debug))
# Start event loop
tornado.ioloop.IOLoop.instance().start()
如何解决这个问题？
Python 3.8 对 Tornado 使用的 asyncio 包进行了 backwards-incompatible 更改。在 Windows 和 Python 3.8 上使用 Tornado 的应用程序必须在其主要 file/function 的开头调用 asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())。 （如 tornadoweb.org 主页上所述）
我使用 pycharm 使用 tornado web 框架编写了一个 python3 web 应用程序项目，
列表服务已经搭建完成。我需要构建剩余的两个组件：用户服务和 public API 层。列表服务的实现可以作为一个很好的起点，以了解更多关于如何使用 Tornado Web 框架构建 Web 应用程序的信息。
我需要使用 tornado 的内置 HTTP 请求框架。
当我尝试 运行 程序时，在收听 ( app.listen(options.port)) 时发生错误：
Traceback (most recent call last):
File "D:/Bill/python/Tornado/99-python-exercise-master/listing_service.py", line 203, in <module>
app.listen(options.port)
File "C:\Program Files\Python38\lib\site-packages\tornado\web.py", line 2116, in listen
server.listen(port, address)
File "C:\Program Files\Python38\lib\site-packages\tornado\tcpserver.py", line 152, in listen
self.add_sockets(sockets)
File "C:\Program Files\Python38\lib\site-packages\tornado\tcpserver.py", line 165, in add_sockets
self._handlers[sock.fileno()] = add_accept_handler(
File "C:\Program Files\Python38\lib\site-packages\tornado\netutil.py", line 279, in add_accept_handler
io_loop.add_handler(sock, accept_handler, IOLoop.READ)
File "C:\Program Files\Python38\lib\site-packages\tornado\platform\asyncio.py", line 100, in add_handler
self.asyncio_loop.add_reader(fd, self._handle_events, fd, IOLoop.READ)
File "C:\Program Files\Python38\lib\asyncio\events.py", line 501, in add_reader
raise NotImplementedError
NotImplementedError
代码：
import tornado.web
import tornado.log
import tornado.options
import sqlite3
import logging
import json
import time
class App(tornado.web.Application):
def __init__(self, handlers, **kwargs):
super().__init__(handlers, **kwargs)
# Initialising db connection
self.db = sqlite3.connect("listings.db")
self.db.row_factory = sqlite3.Row
self.init_db()
def init_db(self):
cursor = self.db.cursor()
# Create table
cursor.execute(
"CREATE TABLE IF NOT EXISTS 'listings' ("
+ "id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT,"
+ "user_id INTEGER NOT NULL,"
+ "listing_type TEXT NOT NULL,"
+ "price INTEGER NOT NULL,"
+ "created_at INTEGER NOT NULL,"
+ "updated_at INTEGER NOT NULL"
+ ");"
)
self.db.commit()
class BaseHandler(tornado.web.RequestHandler):
def write_json(self, obj, status_code=200):
self.set_header("Content-Type", "application/json")
self.set_status(status_code)
self.write(json.dumps(obj))
# /listings
class ListingsHandler(BaseHandler):
@tornado.gen.coroutine
def get(self):
# Parsing pagination params
page_num = self.get_argument("page_num", 1)
page_size = self.get_argument("page_size", 10)
try:
page_num = int(page_num)
except:
logging.exception("Error while parsing page_num: {}".format(page_num))
self.write_json({"result": False, "errors": "invalid page_num"}, status_code=400)
return
try:
page_size = int(page_size)
except:
logging.exception("Error while parsing page_size: {}".format(page_size))
self.write_json({"result": False, "errors": "invalid page_size"}, status_code=400)
return
# Parsing user_id param
user_id = self.get_argument("user_id", None)
if user_id is not None:
try:
user_id = int(user_id)
except:
self.write_json({"result": False, "errors": "invalid user_id"}, status_code=400)
return
# Building select statement
select_stmt = "SELECT * FROM listings"
# Adding user_id filter clause if param is specified
if user_id is not None:
select_stmt += " WHERE user_id=?"
# Order by and pagination
limit = page_size
offset = (page_num - 1) * page_size
select_stmt += " ORDER BY created_at DESC LIMIT ? OFFSET ?"
# Fetching listings from db
if user_id is not None:
args = (user_id, limit, offset)
else:
args = (limit, offset)
cursor = self.application.db.cursor()
results = cursor.execute(select_stmt, args)
listings = []
for row in results:
fields = ["id", "user_id", "listing_type", "price", "created_at", "updated_at"]
listing = {
field: row[field] for field in fields
}
listings.append(listing)
self.write_json({"result": True, "listings": listings})
@tornado.gen.coroutine
def post(self):
# Collecting required params
user_id = self.get_argument("user_id")
listing_type = self.get_argument("listing_type")
price = self.get_argument("price")
# Validating inputs
errors = []
user_id_val = self._validate_user_id(user_id, errors)
listing_type_val = self._validate_listing_type(listing_type, errors)
price_val = self._validate_price(price, errors)
time_now = int(time.time() * 1e6) # Converting current time to microseconds
# End if we have any validation errors
if len(errors) > 0:
self.write_json({"result": False, "errors": errors}, status_code=400)
return
# Proceed to store the listing in our db
cursor = self.application.db.cursor()
cursor.execute(
"INSERT INTO 'listings' "
+ "('user_id', 'listing_type', 'price', 'created_at', 'updated_at') "
+ "VALUES (?, ?, ?, ?, ?)",
(user_id_val, listing_type_val, price_val, time_now, time_now)
)
self.application.db.commit()
# Error out if we fail to retrieve the newly created listing
if cursor.lastrowid is None:
self.write_json({"result": False, "errors": ["Error while adding listing to db"]}, status_code=500)
return
listing = dict(
id=cursor.lastrowid,
user_id=user_id_val,
listing_type=listing_type_val,
price=price_val,
created_at=time_now,
updated_at=time_now
)
self.write_json({"result": True, "listing": listing})
def _validate_user_id(self, user_id, errors):
try:
user_id = int(user_id)
return user_id
except Exception as e:
logging.exception("Error while converting user_id to int: {}".format(user_id))
errors.append("invalid user_id")
return None
def _validate_listing_type(self, listing_type, errors):
if listing_type not in {"rent", "sale"}:
errors.append("invalid listing_type. Supported values: 'rent', 'sale'")
return None
else:
return listing_type
def _validate_price(self, price, errors):
# Convert string to int
try:
price = int(price)
except Exception as e:
logging.exception("Error while converting price to int: {}".format(price))
errors.append("invalid price. Must be an integer")
return None
if price < 1:
errors.append("price must be greater than 0")
return None
else:
return price
# /listings/ping
class PingHandler(tornado.web.RequestHandler):
@tornado.gen.coroutine
def get(self):
self.write("pong!")
def make_app(options):
return App([
(r"/listings/ping", PingHandler),
(r"/listings", ListingsHandler),
], debug=options.debug)
if __name__ == "__main__":
# Define settings/options for the web app
# Specify the port number to start the web app on (default value is port 6000)
tornado.options.define("port", default=6000)
# Specify whether the app should run in debug mode
# Debug mode restarts the app automatically on file changes
tornado.options.define("debug", default=True)
# Read settings/options from command line
tornado.options.parse_command_line()
# Access the settings defined
options = tornado.options.options
# Create web app
app = make_app(options)
app.listen(options.port)
logging.info("Starting listing service. PORT: {}, DEBUG: {}".format(options.port, options.debug))
# Start event loop
tornado.ioloop.IOLoop.instance().start()
如何解决这个问题？
Python 3.8 对 Tornado 使用的 asyncio 包进行了 backwards-incompatible 更改。在 Windows 和 Python 3.8 上使用 Tornado 的应用程序必须在其主要 file/function 的开头调用 asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())。 （如 tornadoweb.org 主页上所述）