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fetcher.py
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fetcher.py
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import abc
import json
import logging
import math
import time
import requests
from bs4 import BeautifulSoup
import typing
QueryOptions = typing.Dict[str, typing.Union[typing.List[str], str]]
class House:
post_id: int
region: str
section: str
description: str
price_value: int
price_unit: str
area: int
refresh_time: int
raw_data: str
def __init__(self):
pass
def __eq__(self, other):
if not isinstance(other, House):
return False
return self.post_id == other.post_id
@classmethod
def from_json(cls, source) -> "House":
def parse_price(raw_price: str) -> int:
# Price may be something like 10,000~12,000
# or single value 12,000, here we take the higher price
prices = raw_price.split('~')
return int(prices[len(prices)-1].replace(",", ""))
house = cls()
house.post_id = source["post_id"]
house.region = source["region_name"]
house.section = source["section_name"]
house.description = source["fulladdress"]
house.price_value = parse_price(source["price"])
house.price_unit = source["unit"]
house.area = int(source["area"]) # source value could be float
house.refresh_time = source["refreshtime"]
house.raw_data = json.dumps(source)
return house
@classmethod
def to_json(cls, source: "House"):
return json.loads(source.raw_data)
class Fetcher:
"""Fetch house information from 591."""
_root_url: str = "https://rent.591.com.tw/"
_api_url: str = "https://rent.591.com.tw/home/search/rsList"
_house_url_fmt: str = "https://rent.591.com.tw/rent-detail-{}.html"
_scan_delay: float
__static_options: QueryOptions = {
"is_new_list": "1",
"type": "1",
"searchtype": "1",
}
_logger: logging.Logger
def __init__(self, logger: logging.Logger, delay: float) -> None:
self._logger = logger
self._scan_delay = delay
self._session = requests.Session()
self.__make_headers()
def __make_headers(self) -> None:
response = self._session.get(self._root_url)
response.raise_for_status()
soup = BeautifulSoup(response.text, "html.parser")
for tag in soup.select("meta"):
if tag.get("name", None) == "csrf-token":
csrf_token = tag.get("content")
self._session.headers["X-CSRF-TOKEN"] = csrf_token
break
else:
raise RuntimeError("No CSRF token found")
self._logger.info("Find CSRF token: %s", csrf_token)
def get_total(self, query_options: QueryOptions) -> int:
"""Check total house counts for given query option."""
options = {**self.__static_options, **query_options}
response = self._session.get(self._api_url, params=options)
response.raise_for_status()
counts = int(response.json()["records"])
return counts
def __get_houses(self, options: QueryOptions) -> typing.Iterable[House]:
response = self._session.get(self._api_url, params=options)
response.raise_for_status()
data = response.json()["data"]
houses = data.get("data", [])
for house in houses:
yield House.from_json(house)
def get_houses(self, query_options: QueryOptions) -> typing.Iterable[House]:
"""Generate houses from specified search option."""
counts = self.get_total(query_options)
pages = math.ceil(counts / 30)
self._logger.info("Find %d houses, %d pages", counts, pages)
for page in range(pages):
options = {**self.__static_options, **query_options}
options["firstRow"] = str(30 * page)
for house in self.__get_houses(options):
yield house
time.sleep(self._scan_delay)
HouseStore = typing.MutableMapping[int, House]
class Notifier(typing.Protocol):
@abc.abstractmethod
def notify(self, house: House) -> None:
raise NotImplementedError()
UrlGenerator = typing.Callable[[House], str]
def get_591_url(house: House) -> str:
return "https://rent.591.com.tw/rent-detail-{}.html".format(house.post_id)
class Scanner:
_logger: logging.Logger
_store: HouseStore
_fetcher: Fetcher
_scan_delay: float
_notifier: Notifier
def __init__(
self,
logger: logging.Logger,
storage: HouseStore,
notifier: Notifier,
fetcher: Fetcher,
delay: float,
):
self._logger = logger
self._store = storage
self._fetcher = fetcher
self._notifier = notifier
self._scan_delay = delay
def __scan_house_once(self, options: QueryOptions):
self._logger.info("Start next iteration of batch fetch")
for house in self._fetcher.get_houses(options):
if house.post_id in self._store:
continue
self._logger.info("Find new house %s", house.description)
self._logger.info(
"House price: %s, area %s, link %s",
house.price_value,
house.area,
get_591_url(house),
)
self._store[house.post_id] = house
self._notifier.notify(house)
def scan_house(self, options: QueryOptions):
while True:
self.__scan_house_once(options)
time.sleep(self._scan_delay)