How to Access Webpages with Cookies Using Python?

Accessing Webpages with Cookies using Python

When accessing certain webpages, it may be necessary to first authenticate with the server by setting cookies. This is particularly relevant when downloading and parsing webpages that require login authentication. In this guide, we will explore how to use Python 2.6's builtin modules to login to a webpage via HTTP POST and retrieve the corresponding cookies for later usage.

Login and Cookie Retrieval

Suppose we have a website with a login page at "/login.php" and a data page at "/data.php" accessible after successful login. To access the data page, we need to set cookies by sending two POST parameters ("username" and "password") to the login page.

To achieve this in Python, we can use the following steps:

1. Establish an HTTP Session: We start by creating an HTTP session using the session() function from the requests library.
2. Send Login Request: Use the post() method to send the POST parameters to the "/login.php" URL. This will trigger the login process and set the necessary cookies.
3. Retrieve Page Content: Once logged in, we can access the protected "/data.php" page using the get() method.
4. Extract Cookies: The session will automatically maintain any cookies set during the login process. We can examine these cookies by printing the response headers obtained from the get() request.

Code Snippet

The following Python code demonstrates these steps:

<code class="python">from requests import session

payload = {
    'username': 'YOUR_USERNAME',
    'password': 'YOUR_PASSWORD'
}

with session() as c:
    c.post('http://example.com/login.php', data=payload)
    response = c.get('http://example.com/protected_page.php')
    print(response.headers)  # Prints cookie information
    print(response.text)  # Prints the HTML content of the page</code>

By executing this code, we can successfully login to the webpage, retrieve the associated cookies, and access the restricted content at "/data.php" for further processing.

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