如何解决datetime中的错误str？

Question

目标是使用datetime来重复以上内容 http://www.harness.org.au/racing/results/?firstDate=01-01-2019http://www.harness.org.au/racing/results/?firstDate=02-01-2019。。。。到昨天为止 （应在new_url = base_url + str(enddate1)中完成）

然后在href中，我想在meetingfulllisttable中循环以获取name和href，然后从当天的每个曲目中获取结果数据

我当前的错误是“<；=”“datetime.timedelta”和“str”实例之间不支持，后者来自我的while循环。为什么会这样？以前从未使用过datetime

from datetime import datetime, date, timedelta
import requests
import re
from bs4 import BeautifulSoup

base_url = "http://www.harness.org.au/racing/results/?firstDate="
base1_url = "http://www.harness.org.au"

webpage_response = requests.get('http://www.harness.org.au/racing/results/?firstDate=')

soup = BeautifulSoup(webpage_response.content, "html.parser")

format = "%d-%m-%y"
delta = timedelta(days=1)
yesterday = datetime.today() - timedelta(days=1)

yesterday1 = yesterday.strftime(format)
enddate = datetime(2019, 1, 1)
enddate1 = enddate.strftime(format)


while enddate1 <= yesterday1:
    enddate1 =+ timedelta(days=1)

    new_url = base_url + str(enddate1)
    soup12 = requests.get(new_url)
    soup1 = BeautifulSoup(soup12.content, "html.parser")
    table1 = soup1.find('table', class_='meetingListFull')
    for tr in table1.find_all('tr'):
        all_cells = tr.find_all('td')
        track = all_cells.a.href.get_text()
        href = all_cells.get('href')
        trackresults = base1_url + href

Answer 1

这个

yesterday1 = yesterday.strftime(format)

这是一根绳子。这就是为什么你会犯这样的错误