如何从搜索中获得结果URL？

Question

[我正在尝试编写一个程序，该程序对https://echa.europa.eu/进行化学搜索并获得结果。 “搜索化学品”字段位于主页的中间。我想通过提供cas号（例如67-56-1）来搜索每种化学物质，从而得到结果URL。我得到的网址似乎不包含提供的cas号。

https://echa.europa.eu/search-for-chemicals?p_p_id=disssimplesearch_WAR_disssearchportlet&p_p_lifecycle=0&_disssimplesearch_WAR_disssearchportlet_searchOccurred=true&_disssimplesearch_WAR_disssearchportlet_sessionCriteriaId=dissSimpleSearchSessionParam101401584308302720

我尝试将不同的cas号（71-23-8）插入“ p_p_id”字段，但未提供预期的搜索结果。https://echa.europa.eu/search-for-chemicals?p_p_id=71-23-8

我还检查了Chrome请求的GET方法的标头，其中也不包含CAS号。

网站是否使用变量存储输入查询？是否有一种方法或工具可用于获取包括搜索cas号在内的结果URL？

一旦弄清楚了，我将使用Python获取数据并将其保存为excel文件。

谢谢。

Answer 1

您需要通过请求一次主URL来获取JESSIONID cookie，然后在https://echa.europa.eu/search-for-chemicals上发送POST。但这还需要一些必需的URL参数

使用curl和bash：

query="71-23-8"
millis=$(($(date +%s%N)/1000000))
curl -s -I -c cookie.txt 'https://echa.europa.eu/search-for-chemicals'
curl -s -L -b cookie.txt 'https://echa.europa.eu/search-for-chemicals' \
    --data-urlencode "p_p_id=disssimplesearch_WAR_disssearchportlet" \
    --data-urlencode "p_p_lifecycle=1" \
    --data-urlencode "p_p_state=normal" \
    --data-urlencode "p_p_col_id=column-1" \
    --data-urlencode "p_p_col_count=2" \
    --data-urlencode "_disssimplesearch_WAR_disssearchportlet_javax.portlet.action=doSearchAction" \
    --data-urlencode "_disssimplesearch_WAR_disssearchportlet_backURL=https://echa.europa.eu/home?p_p_id=disssimplesearchhomepage_WAR_disssearchportlet&p_p_lifecycle=0&p_p_state=normal&p_p_mode=view&p_p_col_id=column-1&p_p_col_count=2" \
    --data-urlencode "_disssimplesearchhomepage_WAR_disssearchportlet_sessionCriteriaId=" \
    --data "_disssimplesearchhomepage_WAR_disssearchportlet_formDate=$millis" \
    --data "_disssimplesearch_WAR_disssearchportlet_searchOccurred=true" \
    --data "_disssimplesearch_WAR_disssearchportlet_sskeywordKey=$query" \
    --data "_disssimplesearchhomepage_WAR_disssearchportlet_disclaimer=on" \
    --data "_disssimplesearchhomepage_WAR_disssearchportlet_disclaimerCheckbox=on"

使用python并用beautifulsoup刮取>

import requests
from bs4 import BeautifulSoup
import time

url = 'https://echa.europa.eu/search-for-chemicals'
query = '71-23-8'

s = requests.Session()
s.get(url)

r = s.post(url, 
    params = {
        "p_p_id": "disssimplesearch_WAR_disssearchportlet",
        "p_p_lifecycle": "1",
        "p_p_state": "normal",
        "p_p_col_id": "column-1",
        "p_p_col_count": "2",
        "_disssimplesearch_WAR_disssearchportlet_javax.portlet.action": "doSearchAction",
        "_disssimplesearch_WAR_disssearchportlet_backURL": "https://echa.europa.eu/home?p_p_id=disssimplesearchhomepage_WAR_disssearchportlet&p_p_lifecycle=0&p_p_state=normal&p_p_mode=view&p_p_col_id=column-1&p_p_col_count=2",
        "_disssimplesearchhomepage_WAR_disssearchportlet_sessionCriteriaId": ""
    },
    data = {
        "_disssimplesearchhomepage_WAR_disssearchportlet_formDate": int(round(time.time() * 1000)),
        "_disssimplesearch_WAR_disssearchportlet_searchOccurred": "true",
        "_disssimplesearch_WAR_disssearchportlet_sskeywordKey": query,
        "_disssimplesearchhomepage_WAR_disssearchportlet_disclaimer": "on",
        "_disssimplesearchhomepage_WAR_disssearchportlet_disclaimerCheckbox": "on"
    }
)
soup = BeautifulSoup(r.text, "html.parser")
table = soup.find("table")

data = [
    (
        t[0].find("a").text.strip(), 
        t[0].find("a")["href"], 
        t[0].find("div", {"class":"substanceRelevance"}).text.strip(),
        t[1].text.strip(),
        t[2].text.strip(),
        t[3].find("a")["href"] if t[3].find("a") else "",
        t[4].find("a")["href"] if t[4].find("a") else "",
    )
    for t in (t.find_all('td') for t in table.find_all("tr"))
    if len(t) > 0 and t[0].find("a") is not None
]
print(data)
注意，如果在服务器上实际检查了时间戳参数（formDate参数），我已经设置了该参数