Scraping excel from website using python with _doPostBack link url hidden

问题

For last few days I am trying to scrap the following website (link pasted below) which has a few excels and pdfs available in a table. I am able to do it for the home page successfully. There are total 59 pages from which these excels/ pdfs have to be scrapped. In most of the websites I have seen till now there is a query parameter which is available in the site url which changes as you move from one page to another. In this case, we have a _doPostBack function probably because of which the URL remains the same on every page you go to. I looked at multiple solutions and posts which are suggesting to see the parameters of post call and use them but I am not able to make sense of the parameters which are provided in post call (this is the first time I am scrapping a website).

Can someone please suggest some resource which can help me write a code which helps me in moving from one page to another using python. The details are as follows:

Website link - http://accord.fairfactories.org/ffcweb/Web/ManageSuppliers/InspectionReportsEnglish.aspx

My current code which extracts the CAP excel sheet from the home page (this is working perfect and is provided just for reference)

from urllib.request import urlopen
from urllib.request import urlretrieve
from bs4 import BeautifulSoup
import re
import urllib

Base = "http://accord.fairfactories.org/ffcweb/Web"
html = urlopen("http://accord.fairfactories.org/ffcweb/Web/ManageSuppliers/InspectionReportsEnglish.aspx")
bs = BeautifulSoup(html)
name = bs.findAll("td", {"class":"column_style_right column_style_left"})
i = 1
for link in bs.findAll("a", {"id":re.compile("CAP(?!\w)")}):
    if 'href' in link.attrs:
        name = str(i)+".xlsx"
        a = link.attrs['href']
        b = a.strip("..")
        c = Base+b
        urlretrieve(c, name)
        i = i+1

Please let me know if I have missed anything while providing the information and please don't rate me -ve else I won't be able to ask any questions further

回答1:

For aspx sites, you need to look for things like __EVENTTARGET, __EVENTVALIDATION etc.. and post those parameters with each request, this will get all the pages and using requests with bs4:

import requests
from bs4 import BeautifulSoup
from urlparse import urljoin # python 3 use from urllib.parse import urljoin   



# All the keys need values set bar __EVENTTARGET, that stays the same.
data = {
    "__EVENTTARGET": "gvFlex",
    "__VIEWSTATE": "",
    "__VIEWSTATEGENERATOR": "",
    "__VIEWSTATEENCRYPTED": "",
    "__EVENTVALIDATION": ""}


def validate(soup, data):
    for k in data:
        # update post values in data.
        if k != "__EVENTTARGET":
            data[k] = soup.select_one("#{}".format(k))["value"]


def get_all_excel():
    base = "http://accord.fairfactories.org/ffcweb/Web"
    url = "http://accord.fairfactories.org/ffcweb/Web/ManageSuppliers/InspectionReportsEnglish.aspx"
    with requests.Session() as s:
        # Add a user agent for each subsequent request.
        s.headers.update({"User-Agent": "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:47.0) Gecko/20100101 Firefox/47.0"})
        r = s.get(url)
        bs = BeautifulSoup(r.content, "lxml")
        # get links from initial page.
        for xcl in bs.select("a[id*=CAP]"):
            yield urljoin(base, xcl["href"])
        # need to re-validate the post data in our dict for each request.
        validate(bs, data)
        last = bs.select_one("a[href*=Page$Last]")
        i = 2
        # keep going until the last page button is not visible
        while last:
            # Increase the counter to set the target to the next page
            data["__EVENTARGUMENT"] = "Page${}".format(i)
            r = s.post(url, data=data)
            bs = BeautifulSoup(r.content, "lxml")
            for xcl in bs.select("a[id*=CAP]"):
                yield urljoin(base, xcl["href"])
            last = bs.select_one("a[href*=Page$Last]")
            # again re-validate for next request
            validate(bs, data)
            i += 1


for x in (get_all_excel()):
    print(x)

If we run it on the first three pages, you can see we get the data you want:

http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9965
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9552
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10650
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11969
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10086
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10905
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10840
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9229
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11310
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9178
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9614
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9734
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10063
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10871
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9468
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9799
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9278
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=12252
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9342
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9966
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11595
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9652
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10271
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10365
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10087
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9967
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11740
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=12375
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11643
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10952
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=12013
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9810
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10953
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10038
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9664
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=12256
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9262
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9210
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9968
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9811
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11610
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9455
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11899
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10273
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9766
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9969
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10088
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10366
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9393
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9813
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11795
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9814
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11273
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=12187
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10954
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9556
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11709
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9676
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10251
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10602
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10089
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9908
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10358
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9469
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11333
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9238
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9816
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9817
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10736
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10622
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9394
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9818
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=10592
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=9395
http://accord.fairfactories.org/Utilities/DownloadFile.aspx?id=11271

来源：https://stackoverflow.com/questions/38554235/scraping-excel-from-website-using-python-with-dopostback-link-url-hidden

标签

python

web-scraping

dopostback