Login to website in Python

flow

1. Go to the login page of the service you want to log in to and check the login form parameters
2. Send the required information to the login URL and start the session

In the following, we will use Qiita as an example.

How to check the parameters

The source of the Qiita login form is as follows:

<form class="landingLoginForm" autocomplete="off" data-event_name="Login with password" action="/login" accept-charset="UTF-8" method="post">
  <input name="utf8" type="hidden" value="✓">
  <input type="hidden" name="authenticity_token" value="rYIMTVoDlb4eCzh6wZIRgiPQHmrr5ts9DyykDCE9FkHM7zQxX7WAhmUhW8y0BPIA3MvzH31KCFEyiPTVk4GBzQ==">
  <input type="text" name="identity" id="identity" placeholder="Username or email" autofocus="autofocus" class="form-control landingLoginForm_identity">
  <div class="row">
    <div class="col-sm-9 landingLoginForm_passwordColumn">
      <input type="password" name="password" id="password" placeholder="Password" class="form-control">
    </div>
    <div class="col-sm-3 landingLoginForm_submitColumn">
      <input type="submit" name="commit" value="Login" class="btn btn-primary btn-block" data-disable-with="Login">
    </div>
  </div>
  <div class="landingLoginForm_forgotPassword">
  	<a href="https://qiita.com/sessions/forgot_password">Forgot Password?</a>
  </div>
  <div class="help-block js-email-invalid-message" style="display: none"></div>
</form>

これより、ログインボタンを押すとqiita.com/loginに

1. utf8
2. authenticity_token
3. identity
4. password

It can be seen that the data is transmitted. Of these, utf8 is given a default value, so use it, and authenticity_token is given a value for each access, so you need to get it. Enter the information by hand in the remaining identity and `` `password```.

Communication with the site

Python has a convenient library for HTTP communication called requests, so it's safe to use it. After logging in, it is necessary to save the value for session, so communicate via the `` `Session``` object.

Also, as mentioned above, it is necessary to obtain authenticity_token before logging in, so first access the top page and BeautifulSoup. Get the value with /).

Below is a sample script to log in to Qiita:

from bs4 import BeautifulSoup
import requests

payload = {
    'utf8': '✓',
    'identity': 'username or email',
    'password': 'secret'
}

# authenticity_Get token
s = requests.Session()
r = s.get('https://qiita.com')
soup = BeautifulSoup(r.text)
auth_token = soup.find(attrs={'name': 'authenticity_token'}).get('value')
payload['authenticity_token'] = auth_token

#Login
s.post('https://qiita.com/login', data=payload)

#Perform the processing that is possible after logging in below
...

Caution

In some cases, the above simple method does not work (for example, two-step authentication is required to log in to Google), so it is necessary to check the HTTP header information etc. in detail each time. ..