Http error 404 not found python

I wrote a script to find spelling mistakes in SO questions’ titles.
I used it for about a month.This was working fine.

But now, when I try to run it, I am getting this.

Traceback (most recent call last):
  File "copyeditor.py", line 32, in <module>
    find_bad_qn(i)
  File "copyeditor.py", line 15, in find_bad_qn
    html = urlopen(url)
  File "/usr/lib/python3.4/urllib/request.py", line 161, in urlopen
    return opener.open(url, data, timeout)
  File "/usr/lib/python3.4/urllib/request.py", line 469, in open
    response = meth(req, response)
  File "/usr/lib/python3.4/urllib/request.py", line 579, in http_response
    'http', request, response, code, msg, hdrs)
  File "/usr/lib/python3.4/urllib/request.py", line 507, in error
    return self._call_chain(*args)
  File "/usr/lib/python3.4/urllib/request.py", line 441, in _call_chain
    result = func(*args)
  File "/usr/lib/python3.4/urllib/request.py", line 587, in http_error_default
    raise HTTPError(req.full_url, code, msg, hdrs, fp)
urllib.error.HTTPError: HTTP Error 404: Not Found

This is my code

import json
from urllib.request import urlopen
from bs4 import BeautifulSoup
from enchant import DictWithPWL
from enchant.checker import SpellChecker

my_dict = DictWithPWL("en_US", pwl="terms.dict")
chkr = SpellChecker(lang=my_dict)
result = []


def find_bad_qn(a):
    url = "https://stackoverflow.com/questions?page=" + str(a) + "&sort=active"
    html = urlopen(url)
    bsObj = BeautifulSoup(html, "html5lib")
    que = bsObj.find_all("div", class_="question-summary")
    for div in que:
        link = div.a.get('href')
        name = div.a.text
        chkr.set_text(name.lower())
        list1 = []
        for err in chkr:
            list1.append(chkr.word)
        if (len(list1) > 1):
            str1 = ' '.join(list1)
            result.append({'link': link, 'name': name, 'words': str1})


print("Please Wait.. it will take some time")
for i in range(298314,298346):
    find_bad_qn(i)
for qn in result:
    qn['link'] = "https://stackoverflow.com" + qn['link']
for qn in result:
    print(qn['link'], " Error Words:", qn['words'])
    url = qn['link']

UPDATE

This is the url causing the problem.Even though this url exists.

https://stackoverflow.com/questions?page=298314&sort=active

I tried changing the range to some lower values. It works fine now.

Why this happened with above url?

Hi guys! In this tutorial, we will learn how to catch an HTTP 404 error in Python. There are many instances when we encounter an HTTP error with error code 404 on the internet. This error indicates that the requested page was not found. This tutorial will teach you how you can use Python to spot pages with such an error. Let’s see more on this with example programs.

Catch HTTP 404 error in Python

There are many methods for catching a 404 error. We will import the urllib or urllib3 library in this post for catching a 404 error. These library has required methods and attributes for our purpose. Let’s see the code and understand how it’s done.

Method 1

See the below example to find out a page with an HTTP 404 error.

import urllib3

http = urllib3.PoolManager()
error = http.request("GET", "https://www.google.com/404")
if (error.status == 404):
    print("HTTP 404 ERROR")

The output for the above code is:

HTTP 404 ERROR

In the above example, we have used the PoolManager of urllib3 to create an http object. A PoolManager instance is needed to make requests. Then we have used the request method to get an HTTPResponse object for the web page ‘https://www.google.com/404’. This HTTPResponse object contains status, data, and header. We check whether the status for this page is 404 if so we print that this is an HTTP error.

Method 2

In this method, we will import the Python urllib library. Have a look at the given code and try to understand.

import urllib.request, urllib.error

try:
    con = urllib.request.urlopen('http://www.google.com/404')

except urllib.error.HTTPError as err:
    print('HTTP', err.code, 'ERROR')

The output of the program:

HTTP 404 ERROR

As you can see, the urlopen() method opens the given URL for us. We have used try and except blocks to catch the HTTP error using urllib.error.HTTPError. If any error is raised while opening the URL, the control is given to except block and there we print the error code for HTTP error.

Thank you.

Also read: How to handle an attribute error in Python

Introduction

You may also find useful the following article on fetching web resources with Python:

• Basic Authentication — A tutorial on Basic Authentication, with examples in Python.

urllib.request is a Python module for fetching URLs (Uniform Resource Locators). It offers a very simple interface, in the form of the urlopen function. This is capable of fetching URLs using a variety of different protocols. It also offers a slightly more complex interface for handling common situations — like basic authentication, cookies, proxies and so on. These are provided by objects called handlers and openers.

urllib.request supports fetching URLs for many “URL schemes” (identified by the string before the ":" in URL — for example "ftp" is the URL scheme of "ftp://python.org/") using their associated network protocols (e.g. FTP, HTTP). This tutorial focuses on the most common case, HTTP.

For straightforward situations urlopen is very easy to use. But as soon as you encounter errors or non-trivial cases when opening HTTP URLs, you will need some understanding of the HyperText Transfer Protocol. The most comprehensive and authoritative reference to HTTP is RFC 2616. This is a technical document and not intended to be easy to read. This HOWTO aims to illustrate using urllib, with enough detail about HTTP to help you through. It is not intended to replace the urllib.request docs, but is supplementary to them.

Fetching URLs

The simplest way to use urllib.request is as follows:

import urllib.request
with urllib.request.urlopen('http://python.org/') as response:
   html = response.read()

If you wish to retrieve a resource via URL and store it in a temporary location, you can do so via the shutil.copyfileobj() and tempfile.NamedTemporaryFile() functions:

import shutil
import tempfile
import urllib.request

with urllib.request.urlopen('http://python.org/') as response:
    with tempfile.NamedTemporaryFile(delete=False) as tmp_file:
        shutil.copyfileobj(response, tmp_file)

with open(tmp_file.name) as html:
    pass

Many uses of urllib will be that simple (note that instead of an ‘http:’ URL we could have used a URL starting with ‘ftp:’, ‘file:’, etc.). However, it’s the purpose of this tutorial to explain the more complicated cases, concentrating on HTTP.

HTTP is based on requests and responses — the client makes requests and servers send responses. urllib.request mirrors this with a Request object which represents the HTTP request you are making. In its simplest form you create a Request object that specifies the URL you want to fetch. Calling urlopen with this Request object returns a response object for the URL requested. This response is a file-like object, which means you can for example call .read() on the response:

import urllib.request

req = urllib.request.Request('http://www.voidspace.org.uk')
with urllib.request.urlopen(req) as response:
   the_page = response.read()

Note that urllib.request makes use of the same Request interface to handle all URL schemes. For example, you can make an FTP request like so:

req = urllib.request.Request('ftp://example.com/')

In the case of HTTP, there are two extra things that Request objects allow you to do: First, you can pass data to be sent to the server. Second, you can pass extra information (“metadata”) about the data or the about request itself, to the server — this information is sent as HTTP “headers”. Let’s look at each of these in turn.

Data

Sometimes you want to send data to a URL (often the URL will refer to a CGI (Common Gateway Interface) script or other web application). With HTTP, this is often done using what’s known as a POST request. This is often what your browser does when you submit a HTML form that you filled in on the web. Not all POSTs have to come from forms: you can use a POST to transmit arbitrary data to your own application. In the common case of HTML forms, the data needs to be encoded in a standard way, and then passed to the Request object as the data argument. The encoding is done using a function from the urllib.parse library.

import urllib.parse
import urllib.request

url = 'http://www.someserver.com/cgi-bin/register.cgi'
values = {'name' : 'Michael Foord',
          'location' : 'Northampton',
          'language' : 'Python' }

data = urllib.parse.urlencode(values)
data = data.encode('ascii') # data should be bytes
req = urllib.request.Request(url, data)
with urllib.request.urlopen(req) as response:
   the_page = response.read()

Note that other encodings are sometimes required (e.g. for file upload from HTML forms — see HTML Specification, Form Submission for more details).

If you do not pass the data argument, urllib uses a GET request. One way in which GET and POST requests differ is that POST requests often have “side-effects”: they change the state of the system in some way (for example by placing an order with the website for a hundredweight of tinned spam to be delivered to your door). Though the HTTP standard makes it clear that POSTs are intended to always cause side-effects, and GET requests never to cause side-effects, nothing prevents a GET request from having side-effects, nor a POST requests from having no side-effects. Data can also be passed in an HTTP GET request by encoding it in the URL itself.

This is done as follows:

>>> import urllib.request
>>> import urllib.parse
>>> data = {}
>>> data['name'] = 'Somebody Here'
>>> data['location'] = 'Northampton'
>>> data['language'] = 'Python'
>>> url_values = urllib.parse.urlencode(data)
>>> print(url_values)  # The order may differ from below.  
name=Somebody+Here&language=Python&location=Northampton
>>> url = 'http://www.example.com/example.cgi'
>>> full_url = url + '?' + url_values
>>> data = urllib.request.urlopen(full_url)

Notice that the full URL is created by adding a ? to the URL, followed by the encoded values.

Headers

We’ll discuss here one particular HTTP header, to illustrate how to add headers to your HTTP request.

Some websites (Google for example) dislike being browsed by programs, or send different versions to different browsers (Browser sniffing is a very bad practice for website design — building sites using web standards is much more sensible. Unfortunately a lot of sites still send different versions to different browsers.). By default urllib identifies itself as Python-urllib/x.y (where x and y are the major and minor version numbers of the Python release, e.g. Python-urllib/2.5), which may confuse the site, or just plain not work. The way a browser identifies itself is through the User-Agent header (The user agent for MSIE 6 is ‘Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)’). When you create a Request object you can pass a dictionary of headers in. The following example makes the same request as above, but identifies itself as a version of Internet Explorer.

For details of more HTTP request headers, see Quick Reference to HTTP Headers.import urllib.parse

import urllib.request

url = 'http://www.someserver.com/cgi-bin/register.cgi'
user_agent = 'Mozilla/5.0 (Windows NT 6.1; Win64; x64)'
values = {'name': 'Michael Foord',
          'location': 'Northampton',
          'language': 'Python' }
headers = {'User-Agent': user_agent}

data = urllib.parse.urlencode(values)
data = data.encode('ascii')
req = urllib.request.Request(url, data, headers)
with urllib.request.urlopen(req) as response:
   the_page = response.read()

The response also has two useful methods. See the section on info and geturl which comes after we have a look at what happens when things go wrong.

Handling Exceptions

urlopen raises URLError when it cannot handle a response (though as usual with Python APIs, built-in exceptions such as ValueError, TypeError etc. may also be raised).

HTTPError is the subclass of URLError raised in the specific case of HTTP URLs.

The exception classes are exported from the urllib.error module.

URLError

Often, URLError is raised because there is no network connection (no route to the specified server), or the specified server doesn’t exist. In this case, the exception raised will have a ‘reason’ attribute, which is a tuple containing an error code and a text error message.

e.g.

>>> req = urllib.request.Request('http://www.pretend_server.org')
>>> try: urllib.request.urlopen(req)
... except urllib.error.URLError as e:
...     print(e.reason)      
...
(4, 'getaddrinfo failed')

HTTPError

Every HTTP response from the server contains a numeric “status code”. Sometimes the status code indicates that the server is unable to fulfil the request. The default handlers will handle some of these responses for you (for example, if the response is a “redirection” that requests the client fetch the document from a different URL, urllib will handle that for you). For those it can’t handle, urlopen will raise an HTTPError. Typical errors include ‘404’ (page not found), ‘403’ (request forbidden), and ‘401’ (authentication required).

See section 10 of RFC 2616 for a reference on all the HTTP error codes.

The HTTPError instance raised will have an integer ‘code’ attribute, which corresponds to the error sent by the server.

Error Codes

Because the default handlers handle redirects (codes in the 300 range), and codes in the 100–299 range indicate success, you will usually only see error codes in the 400–599 range.

http.server.BaseHTTPRequestHandler.responses is a useful dictionary of response codes in that shows all the response codes used by RFC 2616. The dictionary is reproduced here for convenience

# Table mapping response codes to messages; entries have the
# form {code: (shortmessage, longmessage)}.
responses = {
    100: ('Continue', 'Request received, please continue'),
    101: ('Switching Protocols',
          'Switching to new protocol; obey Upgrade header'),

    200: ('OK', 'Request fulfilled, document follows'),
    201: ('Created', 'Document created, URL follows'),
    202: ('Accepted',
          'Request accepted, processing continues off-line'),
    203: ('Non-Authoritative Information', 'Request fulfilled from cache'),
    204: ('No Content', 'Request fulfilled, nothing follows'),
    205: ('Reset Content', 'Clear input form for further input.'),
    206: ('Partial Content', 'Partial content follows.'),

    300: ('Multiple Choices',
          'Object has several resources -- see URI list'),
    301: ('Moved Permanently', 'Object moved permanently -- see URI list'),
    302: ('Found', 'Object moved temporarily -- see URI list'),
    303: ('See Other', 'Object moved -- see Method and URL list'),
    304: ('Not Modified',
          'Document has not changed since given time'),
    305: ('Use Proxy',
          'You must use proxy specified in Location to access this '
          'resource.'),
    307: ('Temporary Redirect',
          'Object moved temporarily -- see URI list'),

    400: ('Bad Request',
          'Bad request syntax or unsupported method'),
    401: ('Unauthorized',
          'No permission -- see authorization schemes'),
    402: ('Payment Required',
          'No payment -- see charging schemes'),
    403: ('Forbidden',
          'Request forbidden -- authorization will not help'),
    404: ('Not Found', 'Nothing matches the given URI'),
    405: ('Method Not Allowed',
          'Specified method is invalid for this server.'),
    406: ('Not Acceptable', 'URI not available in preferred format.'),
    407: ('Proxy Authentication Required', 'You must authenticate with '
          'this proxy before proceeding.'),
    408: ('Request Timeout', 'Request timed out; try again later.'),
    409: ('Conflict', 'Request conflict.'),
    410: ('Gone',
          'URI no longer exists and has been permanently removed.'),
    411: ('Length Required', 'Client must specify Content-Length.'),
    412: ('Precondition Failed', 'Precondition in headers is false.'),
    413: ('Request Entity Too Large', 'Entity is too large.'),
    414: ('Request-URI Too Long', 'URI is too long.'),
    415: ('Unsupported Media Type', 'Entity body in unsupported format.'),
    416: ('Requested Range Not Satisfiable',
          'Cannot satisfy request range.'),
    417: ('Expectation Failed',
          'Expect condition could not be satisfied.'),

    500: ('Internal Server Error', 'Server got itself in trouble'),
    501: ('Not Implemented',
          'Server does not support this operation'),
    502: ('Bad Gateway', 'Invalid responses from another server/proxy.'),
    503: ('Service Unavailable',
          'The server cannot process the request due to a high load'),
    504: ('Gateway Timeout',
          'The gateway server did not receive a timely response'),
    505: ('HTTP Version Not Supported', 'Cannot fulfill request.'),
    }

When an error is raised the server responds by returning an HTTP error code and an error page. You can use the HTTPError instance as a response on the page returned. This means that as well as the code attribute, it also has read, geturl, and info, methods as returned by the urllib.response module:

>>> req = urllib.request.Request('http://www.python.org/fish.html')
>>> try:
...     urllib.request.urlopen(req)
... except urllib.error.HTTPError as e:
...     print(e.code)
...     print(e.read())  
...
404
b'<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
  "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">nnn<html
  ...
  <title>Page Not Found</title>n
  ...

Wrapping it Up

So if you want to be prepared for HTTPError or URLError there are two basic approaches. I prefer the second approach.

Number 1

from urllib.request import Request, urlopen
from urllib.error import URLError, HTTPError
req = Request(someurl)
try:
    response = urlopen(req)
except HTTPError as e:
    print('The server couldn't fulfill the request.')
    print('Error code: ', e.code)
except URLError as e:
    print('We failed to reach a server.')
    print('Reason: ', e.reason)
else:
    # everything is fine

Note

The except HTTPError must come first, otherwise except URLError will also catch an HTTPError.

Number 2

from urllib.request import Request, urlopen
from urllib.error import URLError
req = Request(someurl)
try:
    response = urlopen(req)
except URLError as e:
    if hasattr(e, 'reason'):
        print('We failed to reach a server.')
        print('Reason: ', e.reason)
    elif hasattr(e, 'code'):
        print('The server couldn't fulfill the request.')
        print('Error code: ', e.code)
else:
    # everything is fine

info and geturl

The response returned by urlopen (or the HTTPError instance) has two useful methods info() and geturl() and is defined in the module urllib.response..

geturl — this returns the real URL of the page fetched. This is useful because urlopen (or the opener object used) may have followed a redirect. The URL of the page fetched may not be the same as the URL requested.

info — this returns a dictionary-like object that describes the page fetched, particularly the headers sent by the server. It is currently an http.client.HTTPMessage instance.

Typical headers include ‘Content-length’, ‘Content-type’, and so on. See the Quick Reference to HTTP Headers for a useful listing of HTTP headers with brief explanations of their meaning and use.

Openers and Handlers

When you fetch a URL you use an opener (an instance of the perhaps confusingly-named urllib.request.OpenerDirector). Normally we have been using the default opener — via urlopen — but you can create custom openers. Openers use handlers. All the “heavy lifting” is done by the handlers. Each handler knows how to open URLs for a particular URL scheme (http, ftp, etc.), or how to handle an aspect of URL opening, for example HTTP redirections or HTTP cookies.

You will want to create openers if you want to fetch URLs with specific handlers installed, for example to get an opener that handles cookies, or to get an opener that does not handle redirections.

To create an opener, instantiate an OpenerDirector, and then call .add_handler(some_handler_instance) repeatedly.

Alternatively, you can use build_opener, which is a convenience function for creating opener objects with a single function call. build_opener adds several handlers by default, but provides a quick way to add more and/or override the default handlers.

Other sorts of handlers you might want to can handle proxies, authentication, and other common but slightly specialised situations.

install_opener can be used to make an opener object the (global) default opener. This means that calls to urlopen will use the opener you have installed.

Opener objects have an open method, which can be called directly to fetch urls in the same way as the urlopen function: there’s no need to call install_opener, except as a convenience.

Basic Authentication

To illustrate creating and installing a handler we will use the HTTPBasicAuthHandler. For a more detailed discussion of this subject – including an explanation of how Basic Authentication works — see the Basic Authentication Tutorial.

When authentication is required, the server sends a header (as well as the 401 error code) requesting authentication. This specifies the authentication scheme and a ‘realm’. The header looks like: WWW-Authenticate: SCHEME realm="REALM".

e.g.

WWW-Authenticate: Basic realm="cPanel Users"

The client should then retry the request with the appropriate name and password for the realm included as a header in the request. This is ‘basic authentication’. In order to simplify this process we can create an instance of HTTPBasicAuthHandler and an opener to use this handler.

The HTTPBasicAuthHandler uses an object called a password manager to handle the mapping of URLs and realms to passwords and usernames. If you know what the realm is (from the authentication header sent by the server), then you can use a HTTPPasswordMgr. Frequently one doesn’t care what the realm is. In that case, it is convenient to use HTTPPasswordMgrWithDefaultRealm. This allows you to specify a default username and password for a URL. This will be supplied in the absence of you providing an alternative combination for a specific realm. We indicate this by providing None as the realm argument to the add_password method.

The top-level URL is the first URL that requires authentication. URLs “deeper” than the URL you pass to .add_password() will also match.

# create a password manager
password_mgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()

# Add the username and password.
# If we knew the realm, we could use it instead of None.
top_level_url = "http://example.com/foo/"
password_mgr.add_password(None, top_level_url, username, password)

handler = urllib.request.HTTPBasicAuthHandler(password_mgr)

# create "opener" (OpenerDirector instance)
opener = urllib.request.build_opener(handler)

# use the opener to fetch a URL
opener.open(a_url)

# Install the opener.
# Now all calls to urllib.request.urlopen use our opener.
urllib.request.install_opener(opener)

Note

In the above example we only supplied our HTTPBasicAuthHandler to build_opener. By default openers have the handlers for normal situations – ProxyHandler (if a proxy setting such as an http_proxy environment variable is set), UnknownHandler, HTTPHandler, HTTPDefaultErrorHandler, HTTPRedirectHandler, FTPHandler, FileHandler, DataHandler, HTTPErrorProcessor.

top_level_url is in fact either a full URL (including the ‘http:’ scheme component and the hostname and optionally the port number) e.g. "http://example.com/" or an “authority” (i.e. the hostname, optionally including the port number) e.g. "example.com" or "example.com:8080" (the latter example includes a port number). The authority, if present, must NOT contain the “userinfo” component — for example "joe:password@example.com" is not correct.

Proxies

urllib will auto-detect your proxy settings and use those. This is through the ProxyHandler, which is part of the normal handler chain when a proxy setting is detected. Normally that’s a good thing, but there are occasions when it may not be helpful.

urllib opener for SSL proxy (CONNECT method): ASPN Cookbook Recipe

One way to do this is to setup our own ProxyHandler, with no proxies defined. This is done using similar steps to setting up a Basic Authentication handler:

>>> proxy_support = urllib.request.ProxyHandler({})
>>> opener = urllib.request.build_opener(proxy_support)
>>> urllib.request.install_opener(opener)

Note

Currently urllib.request does not support fetching of https locations through a proxy. However, this can be enabled by extending urllib.request as shown in the recipe.

urllib opener for SSL proxy (CONNECT method): ASPN Cookbook Recipe.

Note

HTTP_PROXY will be ignored if a variable REQUEST_METHOD is set; see the documentation on getproxies().

Sockets and Layers

The Python support for fetching resources from the web is layered. urllib uses the http.client library, which in turn uses the socket library.

As of Python 2.3 you can specify how long a socket should wait for a response before timing out. This can be useful in applications which have to fetch web pages. By default the socket module has no timeout and can hang. Currently, the socket timeout is not exposed at the http.client or urllib.request levels. However, you can set the default timeout globally for all sockets using

import socket
import urllib.request

# timeout in seconds
timeout = 10
socket.setdefaulttimeout(timeout)

# this call to urllib.request.urlopen now uses the default timeout
# we have set in the socket module
req = urllib.request.Request('http://www.voidspace.org.uk')
response = urllib.request.urlopen(req)

Модуль Requests не поставляется вместе с Python, поэтому сперва установим его, выполнив команду pip install requests. Теперь попробуем получить веб-страницу. Как обычно, импортируем модуль и вызываем метод requests.get():

>>> import requests
>>> res = requests.get('https://www.python.org')
>>> type(res)
<class 'requests.models.Response'>
>>> res.status_code
200
>>> res.status_code == requests.codes.ok
True
>>> res.encoding
'utf-8'
>>> len(res.text)
48844
>>> print(res.text)
<!doctype html>
<!--[if lt IE 7]>   <html class="no-js ie6 lt-ie7 lt-ie8 lt-ie9"> ...

Метод requests.get() возвращает объект Response. Проверить успешность запроса можно с помощью свойства status_code или вызвать метод raise_for_status() для объекта Response:

>>> res = requests.get('https://www.python.org/bla-bla-bla')
>>> res.raise_for_status()
Traceback (most recent call last):
  File "<pyshell#12>", line 1, in <module>
    res.raise_for_status()
  File "C:pythonlibsite-packagesrequestsmodels.py", line 935, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 404 Client Error: OK for url: https://www.python.org/bla-bla-bla

Если ошибка при загрузке страницы не является критичной для дальнейшей работы, можно обработать исключение:

res = requests.get('https://www.some-host.ru/bla-bla-bla')
try:
    res.raise_for_status()
except Exception as e:
    print('Ошибка при загрузке страницы: ' + str(e))

Ошибка при загрузке страницы: 404 Client Error: Not Found for url: http://www.some-host.ru/bla-bla-bla

При выполнении запроса, модуль requests устанавливает кодировку на основании заголовков HTTP. Эта кодировка используется при обращении к res.text. Если кодировка была определена неправильно, ее можно изменить:

res.encoding = 'ISO-8859-1'

Теперь посмотрим, как получить бинарные данные, например, изображение:

res = requests.get('http://www.some-host.ru/files/slider/4.jpg')
imgFile = open('C:\example\slider.jpg', 'wb')
imgFile.write(res.content)
imgFile.close()

При потоковой загрузке (методу requests.get() надо передать именованный аргумент stream=True) рекомендуется использовать метод iter_content(size), который возвращает порции данных размером size на каждой итерации:

with open(filename, 'wb') as f:
    for chunk in res.iter_content(100000):
        f.write(chunk)

Для передачи параметров в запросе, надо использовать параметр params метода requests.get():

params = {'first': 'первый', 'second': 'второй'}
res = requests.get('http://httpbin.org/get', params = params)
print(res.url)

http://httpbin.org/get?first=%D0%BF%D0%B5%D1%80%D0%B2%D1%8B%D0%B9&second=%D0%B2%D1%82%D0%BE%D1%80%D0%BE%D0%B9

Любой ключ словаря, значение которого None, не будет добавлен к строке запроса URL.

Дополнительно

• Python, библиотека Requests: быстрый старт
• Парсинг сайтов: как скачивать картинки и другие файлы

Поиск:
HTTP • Python • Web-разработка • Модуль

Prerequisite: Creating simple application in Flask

A 404 Error is showed whenever a page is not found. Maybe the owner changed its URL and forgot to change the link or maybe they deleted the page itself. Every site needs a Custom Error page to avoid the user to see the default Ugly Error page.

GeeksforGeeks also has a customized error page. If we type a URL like
www.geeksforgeeks.org/ajneawnewiaiowjf

Default 404 Error

GeeksForGeeks Customized Error Page

It will show an Error 404 page since this URL doesn’t exist. But an error page provides a beautiful layout, helps the user to go back, or even takes them to the homepage after a specific time interval. That is why Custom Error pages are necessary for every website.

Flask provides us with a way to handle the error and return our Custom Error page.

For this, we need to download and import flask. Download the flask through the following commands on CMD.

pip install flask

Using app.py as our Python file to manage templates, 404.html be the file we will return in the case of a 404 error and header.html be the file with header and navbar of a website.

app.py
Flask allows us to make a python file to define all routes and functions. In app.py we have defined the route to the main page (‘/’) and error handler function which is a flask function and we passed 404 error as a parameter.

The above python program will return 404.html file whenever the user opens a broken link.

404.html
The following code exports header and navbar from header.html.
Both files should be stored in templates folder according to the flask.

Automatically Redirecting to the Home page after 5 seconds

The app.py code for this example stays the same as above.
The following code Shows the Custom 404 Error page and starts a countdown of 5 seconds.
After 5 seconds are completed, it redirects the user back to the homepage.
404.html
The following code exports header and navbar from header.html.
Both files should be stored in the templates folder according to the flask.
After 5 seconds, the user will get redirected to the Home Page Automatically.

Sample header.html
This is a sample header.html which includes a navbar just like shown in the image.
It’s made up of bootstrap. You can also make one of your own.
For this one, refer the bootstrap documentation.

Output:
The output will be a custom error page with header.html that the user exported.
The following is an example output with my custom header, footer, and 404.html file.