I'm using Python to scrape data from a number of web pages that have simple HTML input forms, like the 'Username:' form at the bottom of this page:
http://www.w3schools.com/html/html_forms.asp (this is just a simple example to illustrate the problem)
Firefox Inspect Element indicates this form field has the following HTML structure:
<form name="input0" target="_blank" action="html_form_action.asp" method="get">
Username:
<input name="user" size="20" type="text"></input>
<input value="Submit" type="submit"></input>
</form>
All I want to do is fill out this form and get the resulting page:
http://www.w3schools.com/html/html_form_action.asp?user=ThisIsMyUserName
Which is what is produced in my browser by entering 'ThisIsMyUserName' in the 'Username' field and pressing 'Submit'. However, every method that I have tried (details below) returns the contents of the original page containing the unaltered form without any indication the form data I submitted was recognized, i.e. I get the content from the first link above in response to my request, when I expected to receive the content of the second link.
I suspect the problem has to do with action="html_form_action.asp"
in the form above, or perhaps some kind of hidden field I'm missing (I don't know what to look for - I'm new to form submission). Any suggestions?
HERE IS WHAT I'VE TRIED SO FAR:
Using urllib.requests in Python 3:
import urllib.request
import urllib.parse
# Create dict of form values
example_data = urllib.parse.urlencode({'user': 'ThisIsMyUserName'})
# Encode dict
example_data = example_data.encode('utf-8')
# Create request
example_url = 'http://www.w3schools.com/html/html_forms.asp'
request = urllib.request.Request(example_url, data=example_data)
# Create opener and install
my_url_opener = urllib.request.build_opener() # no handlers
urllib.request.install_opener(my_url_opener)
# Open the page and read content
web_page = urllib.request.urlopen(request)
content = web_page.read()
# Save content to file
my_html_file = open('my_html_file.html', 'wb')
my_html_file.write(content)
But what is returned to me and saved in 'my_html_file.html' is the original page containing
the unaltered form without any indication that my form data was recognized, i.e. I get this page in response: qqqhttp://www.w3schools.com/html/html_forms.asp
...which is the same thing I would have expected if I made this request without the
data parameter at all (which would change the request from a POST to a GET).
Naturally the first thing I did was check whether my request was being constructed properly:
# Just double-checking the request is set up correctly
print("GET or POST?", request.get_method())
print("DATA:", request.data)
print("HEADERS:", request.header_items())
Which produces the following output:
GET or POST? POST
DATA: b'user=ThisIsMyUserName'
HEADERS: [('Content-length', '21'), ('Content-type', 'application/x-www-form-urlencoded'), ('User-agent', 'Python-urllib/3.3'), ('Host', 'www.w3schools.com')]
So it appears the POST request has been structured correctly. After re-reading the
documentation and unsuccessfuly searching the web for an answer to this problem, I
moved on to a different tool: the requests module. I attempted to perform the same task:
import requests
example_url = 'http://www.w3schools.com/html/html_forms.asp'
data_to_send = {'user': 'ThisIsMyUserName'}
response = requests.post(example_url, params=data_to_send)
contents = response.content
And I get the same exact result. At this point I'm thinking maybe this is a Python 3
issue. So I fire up my trusty Python 2.7 and try the following:
import urllib, urllib2
data = urllib.urlencode({'user' : 'ThisIsMyUserName'})
resp = urllib2.urlopen('http://www.w3schools.com/html/html_forms.asp', data)
content = resp.read()
And I get the same result again! For thoroughness I figured I'd attempt to achieve the
same result by encoding the dictionary values into the url and attempting a GET request:
# Using Python 3
# Construct the url for the GET request
example_url = 'http://www.w3schools.com/html/html_forms.asp'
form_values = {'user': 'ThisIsMyUserName'}
example_data = urllib.parse.urlencode(form_values)
final_url = example_url + '?' + example_data
print(final_url)
This spits out the following value for final_url:
qqqhttp://www.w3schools.com/html/html_forms.asp?user=ThisIsMyUserName
I plug this into my browser and I see that this page is exactly the same as
the original page, which is exactly what my program is downloading.
I've also tried adding additional headers and cookie support to no avail.
I've tried everything I can think of. Any idea what could be going wrong?