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browser.py
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browser.py
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import requests
import bs4
from six.moves import urllib
from six import string_types
from .form import Form
import webbrowser
import tempfile
from .utils import LinkNotFoundError
from .__version__ import __version__, __title__
import weakref
class Browser(object):
"""Builds a Browser.
:param session: Attach a pre-existing requests Session instead of
constructing a new one.
:param soup_config: Configuration passed to BeautifulSoup to affect
the way HTML is parsed. Defaults to ``{'features': 'lxml'}``.
If overriden, it is highly recommended to `specify a parser
<https://www.crummy.com/software/BeautifulSoup/bs4/doc/#specifying-the-parser-to-use>`__.
Otherwise, BeautifulSoup will issue a warning and pick one for
you, but the parser it chooses may be different on different
machines.
:param requests_adapters: Configuration passed to requests, to affect
the way HTTP requests are performed.
:param raise_on_404: If True, raise :class:`LinkNotFoundError`
when visiting a page triggers a 404 Not Found error.
:param user_agent: Set the user agent header to this value.
See also: :func:`StatefulBrowser`
"""
def __init__(self, session=None, soup_config={'features': 'lxml'},
requests_adapters=None,
raise_on_404=False, user_agent=None):
self.raise_on_404 = raise_on_404
self.session = session or requests.Session()
if hasattr(weakref, 'finalize'):
self._finalize = weakref.finalize(self.session, self.close)
else: # pragma: no cover
# Python < 3 does not have weakref.finalize, but these
# versions accept calling session.close() within __del__
self._finalize = self.close
self.set_user_agent(user_agent)
if requests_adapters is not None:
for adaptee, adapter in requests_adapters.items():
self.session.mount(adaptee, adapter)
self.soup_config = soup_config or dict()
@staticmethod
def add_soup(response, soup_config):
"""Attaches a soup object to a requests response."""
if "text/html" in response.headers.get("Content-Type", ""):
response.soup = bs4.BeautifulSoup(response.content, **soup_config)
else:
response.soup = None
def set_cookiejar(self, cookiejar):
"""Replaces the current cookiejar in the requests session. Since the
session handles cookies automatically without calling this function,
only use this when default cookie handling is insufficient.
:param cookiejar: Any `cookielib.CookieJar
<https://docs.python.org/2/library/cookielib.html#cookielib.CookieJar>`__
compatible object.
"""
self.session.cookies = cookiejar
def get_cookiejar(self):
"""Gets the cookiejar from the requests session."""
return self.session.cookies
def set_user_agent(self, user_agent):
"""Replaces the current user agent in the requests session headers."""
# set a default user_agent if not specified
if user_agent is None:
requests_ua = requests.utils.default_user_agent()
user_agent = '%s (%s/%s)' % (requests_ua, __title__, __version__)
# the requests module uses a case-insensitive dict for session headers
self.session.headers['User-agent'] = user_agent
def request(self, *args, **kwargs):
"""Straightforward wrapper around `requests.Session.request
<http://docs.python-requests.org/en/master/api/#requests.Session.request>`__.
:return: `requests.Response
<http://docs.python-requests.org/en/master/api/#requests.Response>`__
object with a *soup*-attribute added by :func:`add_soup`.
This is a low-level function that should not be called for
basic usage (use :func:`get` or :func:`post` instead). Use it if you
need an HTTP verb that MechanicalSoup doesn't manage (e.g. MKCOL) for
example.
"""
response = self.session.request(*args, **kwargs)
Browser.add_soup(response, self.soup_config)
return response
def get(self, *args, **kwargs):
"""Straightforward wrapper around `requests.Session.get
<http://docs.python-requests.org/en/master/api/#requests.Session.get>`__.
:return: `requests.Response
<http://docs.python-requests.org/en/master/api/#requests.Response>`__
object with a *soup*-attribute added by :func:`add_soup`.
"""
response = self.session.get(*args, **kwargs)
if self.raise_on_404 and response.status_code == 404:
raise LinkNotFoundError()
Browser.add_soup(response, self.soup_config)
return response
def post(self, *args, **kwargs):
"""Straightforward wrapper around `requests.Session.post
<http://docs.python-requests.org/en/master/api/#requests.Session.post>`__.
:return: `requests.Response
<http://docs.python-requests.org/en/master/api/#requests.Response>`__
object with a *soup*-attribute added by :func:`add_soup`.
"""
response = self.session.post(*args, **kwargs)
Browser.add_soup(response, self.soup_config)
return response
def _request(self, form, url=None, **kwargs):
method = str(form.get("method", "get"))
action = form.get("action")
url = urllib.parse.urljoin(url, action)
if url is None: # This happens when both `action` and `url` are None.
raise ValueError('no URL to submit to')
# read http://www.w3.org/TR/html5/forms.html
data = kwargs.pop("data", dict())
files = kwargs.pop("files", dict())
for input in form.select("input[name], button[name]"):
name = input.get("name")
if input.get("type") in ("radio", "checkbox"):
if "checked" not in input.attrs:
continue
value = input.get("value", "on")
else:
# web browsers use empty string for inputs with missing values
value = input.get("value", "")
if input.get("type") == "checkbox":
data.setdefault(name, []).append(value)
elif input.get("type") == "file":
# read http://www.cs.tut.fi/~jkorpela/forms/file.html
# in web browsers, file upload only happens if the form"s (or
# submit button"s) enctype attribute is set to
# "multipart/form-data". we don"t care, simplify.
if not value:
continue
if isinstance(value, string_types):
value = open(value, "rb")
files[name] = value
else:
data[name] = value
for textarea in form.select("textarea"):
name = textarea.get("name")
if not name:
continue
data[name] = textarea.text
for select in form.select("select"):
name = select.get("name")
if not name:
continue
multiple = "multiple" in select.attrs
values = []
for i, option in enumerate(select.select("option")):
if (i == 0 and not multiple) or "selected" in option.attrs:
values.append(option.get("value", ""))
if multiple:
data[name] = values
elif values:
data[name] = values[-1]
if method.lower() == "get":
kwargs["params"] = data
else:
kwargs["data"] = data
return self.session.request(method, url, files=files, **kwargs)
def submit(self, form, url=None, **kwargs):
"""Prepares and sends a form request.
:param form: The filled-out form.
:param url: URL of the page the form is on. If the form action is a
relative path, then this must be specified.
:param \*\*kwargs: Arguments forwarded to `requests.Session.request
<http://docs.python-requests.org/en/master/api/#requests.Session.request>`__.
:return: `requests.Response
<http://docs.python-requests.org/en/master/api/#requests.Response>`__
object with a *soup*-attribute added by :func:`add_soup`.
"""
if isinstance(form, Form):
form = form.form
response = self._request(form, url, **kwargs)
Browser.add_soup(response, self.soup_config)
return response
def launch_browser(self, soup):
"""Launch a browser to display a page, for debugging purposes.
:param: soup: Page contents to display, supplied as a bs4 soup object.
"""
with tempfile.NamedTemporaryFile(delete=False) as file:
file.write(soup.encode())
webbrowser.open('file://' + file.name)
def close(self):
"""Close the current session, if still open."""
if self.session is not None:
self.session.cookies.clear()
self.session.close()
self.session = None
def __del__(self):
self._finalize()
def __enter__(self):
return self
def __exit__(self, *args):
self.close()