How to Automate Course Registration on a Legacy University System with Python

When university course selection times clash with personal schedules, a Python script can automate the registration process. The first step is to simulate login, preserve the session, and then perform the necessary actions.

Attempt Login

Open the university’s academic system in a browser, fill in any values, and submit the form. Use Chrome DevTools → Network to capture the request.

Filter out CSS and images; you will see a request to default.aspx.

If the system does not use cookies, the real request URL looks like:

http://110.65.10.xxx/(bdq1aj45lpd42o55vqpfgpie)/default2.aspx

The part inside the parentheses changes each time; it is a session identifier used by ASP.NET when cookies are disabled.

Get Session Information (No Cookie)

Use the requests library and spoof the User‑Agent header.

class Spider:
    def __init__(self, url):
        self.__uid = ''
        self.__real_base_url = ''
        self.__base_url = url
        self.__headers = {
            'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.62 Safari/537.36',
        }
    def __set_real_url(self):
        request = requests.get(self.__base_url, headers=self.__headers)
        real_url = request.url
        self.__real_base_url = real_url[:len(real_url) - len('default2.aspx')]
        return request

The returned URL contains the session information; store it as your_ip/(bdq1aj45lpd42o55vqpfgpie)/ for later requests.

Get Session Information (Using Cookie)

If the system uses cookies, simply capture the cookie on the first GET request and reuse it:

def get_cookie():
    request = requests.get('http://xxx.xxx.xxx.xxx')  # example URL
    cookie = request.cookies
    return cookie

def use_cookie(cookie):
    request = requests.get('http://xxx.xxx.xxx.xxx', cookies=cookie)

For the school in this tutorial, the no‑cookie method is used.

CAPTCHA Handling

The login page includes a CAPTCHA image with src="CheckCode.aspx". Download it with requests and display it for manual input:

def __get_code(self):
    request = requests.get(self.__real_base_url + 'CheckCode.aspx', headers=self.__headers)
    with open('code.jpg', 'wb') as f:
        f.write(request.content)
    im = Image.open('code.jpg')
    im.show()
    code = input('Please input the code:')
    return code

Construct Login Data

Parse the login page to obtain the hidden __VIEWSTATE field using BeautifulSoup:

def __get_login_data(self, uid, password):
    request = self.__set_real_url()
    soup = BeautifulSoup(request.text, 'lxml')
    __VIEWSTATE = soup.find('input', attrs={'name': '__VIEWSTATE'})['value']
    code = self.__get_code()
    data = {
        '__VIEWSTATE': __VIEWSTATE,
        'txtUserName': self.__uid,
        'TextBox2': password,
        'txtSecretCode': code,
        'RadioButtonList1': '学生'.encode('gb2312'),
        'Button1': '',
        'lbLanguage': '',
        'hidPdrs': '',
        'hidsc': ''
    }
    return data

Submit the login request and verify success by checking for the student’s name in the returned page:

def login(self, uid, password):
    while True:
        data = self.__get_login_data(uid, password)
        request = requests.post(self.__real_base_url + 'default2.aspx', headers=self.__headers, data=data)
        soup = BeautifulSoup(request.text, 'lxml')
        try:
            name_tag = soup.find(id='xhxm')
            self.__name = name_tag.string[:len(name_tag.string)-2]
            print('欢迎' + self.__name)
            return True
        except Exception:
            print('Unknown Error, try to login again.')
            time.sleep(0.5)
            continue

Fetch Course Information

After logging in, request the public course selection page. Add a Referer header pointing to the current page. Encode the student name in gb2312 before sending.

def __enter_lessons_first(self):
    data = {
        'xh': self.__uid,
        'xm': self.__name.encode('gb2312'),
        'gnmkdm': 'N121103',
        'TextBox1': '',
        'dpkcmcGrid:txtChoosePage': '1',
        'dpkcmcGrid:txtPageSize': '200',
        # other hidden fields omitted for brevity
    }
    self.__headers['Referer'] = self.__real_base_url + 'xs_main.aspx?xh=' + self.__uid
    request = requests.get(self.__real_base_url + 'xf_xsqxxxk.aspx', params=data, headers=self.__headers)
    self.__headers['Referer'] = request.url
    soup = BeautifulSoup(request.text, 'lxml')
    self.__set__VIEWSTATE(soup)

Parse Course List

Define a Lesson class to store course details, then extract each row from the course table:

class Lesson:
    def __init__(self, name, code, teacher_name, time, number):
        self.name = name
        self.code = code
        self.teacher_name = teacher_name
        self.time = time
        self.number = number

def __search_lessons(self, lesson_name=''):
    self.__base_data['TextBox1'] = lesson_name.encode('gb2312')
    request = requests.post(self.__headers['Referer'], data=self.__base_data, headers=self.__headers)
    soup = BeautifulSoup(request.text, 'lxml')
    self.__set__VIEWSTATE(soup)
    return self.__get_lessons(soup)

def __get_lessons(self, soup):
    lesson_list = []
    lessons_tag = soup.find('table', id='kcmcGrid')
    lesson_tag_list = lessons_tag.find_all('tr')[1:]
    for lesson_tag in lesson_tag_list:
        td_list = lesson_tag.find_all('td')
        code = td_list[0].input['name']
        name = td_list[1].string
        teacher_name = td_list[3].string
        time = td_list[4]['title']
        number = td_list[10].string
        lesson = Lesson(name, code, teacher_name, time, number)
        lesson_list.append(lesson)
    return lesson_list

Select Courses

For each desired lesson, set its hidden field to on and submit the form. Capture any JavaScript alert messages to inform the user about errors such as time conflicts.

def __select_lesson(self, lesson_list):
    data = copy.deepcopy(self.__base_data)
    data['Button1'] = '  提交  '.encode('gb2312')
    for lesson in lesson_list:
        data[lesson.code] = 'on'
        request = requests.post(self.__headers['Referer'], data=data, headers=self.__headers)
        soup = BeautifulSoup(request.text, 'lxml')
        self.__set__VIEWSTATE(soup)
        error_tag = soup.html.head.script
        if error_tag is not None:
            error_text = error_tag.string
            for msg in re.findall("alert\('(.+?)'\);", error_text):
                print(msg)
        # print already selected courses (omitted for brevity)

Summary

The script completes the whole workflow: simulate login, maintain the session (with or without cookies), solve the CAPTCHA, retrieve hidden viewstate, fetch the list of available courses, and automatically submit selections. Because the legacy system uses simple ASP.NET session handling, the process is relatively straightforward, though adjustments may be required for different university deployments.

Author: 小苏打 Source: https://vhyz.me/2018/06/12/用Python实现模拟登录正方教务系统抢课/ GitHub: https://github.com/vhyz/ZF_Spider