Develop Reference

Scraping json content from a site ordered in pages

I'm trying to scrape a site, when I run the following code without region_id=[any number from one to 32] I get a [500], but if I set region_id=1 I'll get only a first page by default (on the url it is pagina=&), pages are up to 500; is there a command or parameter for retrieving every page (every possible value of pagina=), avoiding for loops?
import requests
url = "http://www.enciclovida.mx/explora-por-region/especies-por-grupo?utf8=%E2%9C%93&grupo_id=Plantas&region_id=&parent_id=&pagina=&nombre="
resp = requests.get(url, headers={'User-Agent':'Mozilla/5.0'})
data = resp.json()

Even without a for loop, you are still going to need iteration. You could do it with recursion or map as I've done below, but the iteration is still there. This solution has the advantage that everything is a generator, so only when you ask for a page's json from all_data will url be formatted, the request made, checked and converted to json. I added a filter to make sure you got a valid response before trying to get the json out. It still makes every request sequentially, but you could replace map with a parallel implementation quite easily.
import requests
from itertools import product, starmap
from functools import partial
def is_valid_resp(resp):
return resp.status_code == requests.codes.ok
def get_json(resp):
return resp.json()
# There's a .format hiding on the end of this really long url,
# with {} in appropriate places
url = "http://www.enciclovida.mx/explora-por-region/especies-por-grupo?utf8=%E2%9C%93&grupo_id=Plantas&region_id={}&parent_id=&pagina={}&nombre=".format
regions = range(1, 33)
pages = range(1, 501)
urls = starmap(url, product(regions, pages))
moz_get = partial(requests.get, headers={'User-Agent':'Mozilla/5.0'})
responses = map(moz_get, urls)
valid_responses = filter(is_valid_response, responses)
all_data = map(get_json, valid_responses)
# all_data is a generator that will give you each page's json.

web scraping failure of log in using python requests module

I am trying to develop a script with python to web scraping some information on a specific website for learning purposes.
I went over a lot of different tutorials and posts, trying to gather some insights from them, they are very useful but still didn't help me to find a way to log in the website and do searches with different keywords.
I tried to use different APIs, such as requests and urllib, maybe I didn't find the right way to solve it.
The steps lists as follow:
login information set up
Send login information to the website and get response for future use
keywords setup
import header
set up cookiejar
from login response, do the search
After I tried, it will work randomly, and
here is the code:
import getpass
# marvin
# date:2018/2/7
# login stage preparation
def login_values():
login="https://www.****.com/login"
username = input("Please insert your username: ")
password = getpass.getpass("Please type in your password: ")
host="www.****.com"
#store login screts
data = {
"username": username,
"password": password,
}
return login,host,data
The following is for getting the HTML file from a website
import requests
import random
import http.cookiejar
import socket
# Set up web scraping function to output the html text file
def webscrape(login_url,host_url,login_data,target_url):
#static values preparation
##import header
user_agents = [
***
]
agent = random.choice(user_agents)
headers={'User-agent':agent,
'Accept':'*/*',
'Accept-Language':'en-US,en;q=0.9;zh-cmn-Hans',
'Host':host_url,
'charset':'utf-8',
}
##set up cookie jar
cj = http.cookiejar.CookieJar()
#
# get the html file
socket.setdefaulttimeout(20)
s=requests.Session()
req=s.post(login_url, data=login_data)
res = s.get(target_url, cookies=cj,headers=headers)
html=res.text
return html
Here is the code to get each links from html:
from bs4 import BeautifulSoup
#set up html parsing function for parsing all the list links
def getlist(keyword,loginurl,hosturl,valuesurl,html_lists):
page=1
pagenum=10# set up maximum page num
links=[]
soup=BeautifulSoup(html_lists,"lxml")
try:
for li in soup.find("div",class_="search_pager human_pager in-block").ul.find_all('li'):
target_part=soup.find_all("div",class_="search_result_single search-2017 pb25 pt25 pl30 pr30 ")
[links.append(link.find('a')['href']) for link in target_part]
page+=1
if page<=pagenum:
try:
nexturl=soup.find('div',class_='search_pager human_pager in-block').ul.find('li',class_='pagination-next ng-scope ').a['href'] #next page
except AttributeError:
print("{}'s links are all stored!".format(keyword))
return links
else:
chs_html=webscrape(loginurl,hosturl,valuesurl,nexturl)
soup=BeautifulSoup(chs_html,"lxml")
except AttributeError:
target_part=soup.find_all("div",class_="search_result_single search-2017 pb25 pt25 pl30 pr30 ")
[links.append(link.find('a')['href']) for link in target_part]
print("There is only one page")
return links
The test code is:
keyword="****"
myurl="https://www.****.com/search/os2?key={}".format(keyword)
chs_html=webscrape(login,host,values,myurl)
chs_links=getlist(keyword,login,host,values,chs_html)
targethtml=webscrape(login,host,values,chs_links[1])
There are total 22 links and one page containing 19 links, so it is supposed to have more than one page, if the result "There is only one page" shown up, it indicates a failure.
Problems:
The login_values function is to secure my login information by combining all functions to a final function, but apparently, the username and password are still really easy to show just by print() command.
This the main problem!! Like I mentioned before, this method works randomly. By the way, what I mean not working, it is that the HTML file is only the login page instead of the searching result. I want to get a better control to make it work most of the time. I checked user-agents by print agent every time to see if they are relevant, and it is not! I cleared cookies with suspicious to full storage memory, and it is not.
There are sometimes I facing max trial error or OS error, I guess it is the error from the server I was trying to reach, is there a way I can set up a wait timer for me to prevent these errors from happening?

unable to save data in datastore but no errors

I'm building a web crawler. some of the the data I input into datastore get saved, others do not get saved and I have no idea what is the problem.
here is my crawler class
class Crawler(object):
def get_page(self, url):
try:
req = urllib2.Request(url, headers={'User-Agent': "Magic Browser"}) # yessss!!! with the header, I am able to download pages
#response = urlfetch.fetch(url, method='GET')
#return response.content
#except urlfetch.InvalidURLError as iu:
# return iu.message
response = urllib2.urlopen(req)
return response.read()
except urllib2.HTTPError as e:
return e.reason
def get_all_links(self, page):
return re.findall('http[s]?://(?:[a-zA-Z]|[0-9]|[$-_#.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+',page)
def union(self, lyst1, lyst2):
try:
for elmt in lyst2:
if elmt not in lyst1:
lyst1.append(elmt)
return lyst1
except e:
return e.reason
#function that crawls the web for links starting from the seed
#returns a dictionary of index and graph
def crawl_web(self, seed="http://tonaton.com/"):
query = Listings.query() #create a listings object from storage
if query.get():
objListing = query.get()
else:
objListing = Listings()
objListing.toCrawl = [seed]
objListing.Crawled = []
start_time = datetime.datetime.now()
while datetime.datetime.now()-start_time < datetime.timedelta(0,5):#tocrawl (to crawl can take forever)
try:
#while True:
page = objListing.toCrawl.pop()
if page not in objListing.Crawled:
content = self.get_page(page)
add_page_to_index(page, content)
outlinks = self.get_all_links(content)
graph = Graph() #create a graph object with the url
graph.url = page
graph.links = outlinks #save all outlinks as the value part of the graph url
graph.put()
self.union(objListing.toCrawl, outlinks)
objListing.Crawled.append(page)
except:
return False
objListing.put() #save to database
return True #return true if it works
the classes that define the various ndb Models are in this python module:
import os
import urllib
from google.appengine.ext import ndb
import webapp2
class Listings(ndb.Model):
toCrawl = ndb.StringProperty(repeated=True)
Crawled = ndb.StringProperty(repeated=True)
#let's see how this works
class Index(ndb.Model):
keyword = ndb.StringProperty() # keyword part of the index
url = ndb.StringProperty(repeated=True) # value part of the index
#class Links(ndb.Model):
# links = ndb.JsonProperty(indexed=True)
class Graph(ndb.Model):
url = ndb.StringProperty()
links = ndb.StringProperty(repeated=True)
it used to work fine when I had JsonProperty in place of StringProperty(repeated=true). but JsonProperty is limited to 1500 bytes so I had an error once.
now, when I run the crawl_web member function, it actually crawls but when I check datastore it's only the Index entity that is created. No Graph, no Listing. please help. thanks.

Putting your code together, adding the missing imports, and logging the exception, eventually shows the first killer problem:
Exception Indexed value links must be at most 500 characters
and indeed, adding a logging of outlinks, one easily eyeballs that several of them are far longer than 500 characters -- therefore they can't be items in an indexed property, such as a StringProperty. Changing each repeated StringProperty to a repeated TextProperty (so it does not get indexed and thus has no 500-characters-per-item limitation), the code runs for a while (making a few instances of Graph) but eventually dies with:
An error occured while connecting to the server: Unable to fetch URL: https://sb':'http://b')+'.scorecardresearch.com/beacon.js';document.getElementsByTagName('head')[0].appendChild(s); Error: [Errno 8] nodename nor servname provided, or not known
and indeed, it's pretty obvious tht the alleged "link" is actually a bunch of Javascript and as such cannot be fetched.
So, essentially, the core bug in your code is not at all related to app engine, but rather, the issue is that your regular expression:
'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_#.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+'
does not properly extract outgoing links given a web page containing Javascript as well as HTML.
There are many issues with your code, but to this point they're just slowing it down or making it harder to understand, not killing it -- what's killing it is using that regular expression pattern to try and extract links from the page.
Check out retrieve links from web page using python and BeautifulSoup -- most answers suggest, for the purpose of extracting links from a page, using BeautifulSoup, which may perhaps be a problem in app engine, but one shows how to do it with just Python and REs.

Python 2&3: both urllib & requests POST data mysteriously disappears

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?

The form states an action and a method; you are ignoring both. The method states the form uses GET, not POST, and the action tells you to send the form data to html_form_action.asp.
The action attribute acts like any other URL specifier in an HTML page; unless it starts with a scheme (so with http://..., https://..., etc.) it is relative to the current base URL of the page.
The GET HTTP method adds the URL-encoded form parameters to the target URL with a question mark:
import urllib.request
import urllib.parse
# Create dict of form values
example_data = urllib.parse.urlencode({'user': 'ThisIsMyUserName'})
# Create request
example_url = 'http://www.w3schools.com/html/html_form_action.asp'
get_url = example_url + '?' + example_data
# Open the page and read content
web_page = urllib.request.urlopen(get_url)
print(web_page.read().decode(web_page.info().get_param('charset', 'utf8')))
or, using requests:
import requests
example_url = 'http://www.w3schools.com/html/html_form_action.asp'
data_to_send = {'user': 'ThisIsMyUserName'}
response = requests.get(example_url, params=data_to_send)
contents = response.text
print(contents)
In both examples I also decoded the response to Unicode text (something requests makes easier for me with the response.text attribute).

python fetch data from website sub pages

I am attempting to create a bot that fetches market links from steam but have run into a problem. I was able to return all the data from a single page, but when I attempt to get multiple pages it just gives me copies of the first page though I give it working links (eg: http://steamcommunity.com/market/search?q=appid%3A753#p1 and then http://steamcommunity.com/market/search?q=appid%3A753#p2). I have tested the links and they work in my browser. This is my code.
import urllib2
import random
import time
start_url = "http://steamcommunity.com/market/search?q=appid%3A753"
end_page = 3
urls = []
def get_raw(url):
req = urllib2.Request(url)
response = urllib2.urlopen(req)
return response.read()
def get_market_urls(html):
index = 0
while index != -1:
index = html.find("market_listing_row_link", index+25)
beg = html.find("http", index)
end = html.find('"',beg)
print html[beg:end]
urls.append(html[beg:end])
def go_to_page(page):
return start_url+"#p"+str(page)
def wait(min, max):
wait_t = random.randint(min,max)
time.sleep(wait_t)
for i in range(end_page):
url = go_to_page(i+1)
raw = get_raw(url)
get_market_urls(raw)

Your problem is that you've misunderstood what the URL says.
The number after the hashtag doesn't mean it's a different URL that can be fetched. This is called the query string. In that particular page the query string explains to the javascript which page to pull off AJAX. (Read about it Here and Here if you're interested..).
Anyway, you shoul look at the url: http://steamcommunity.com/market/search/render/?query=appid%3A753&start=00&count=10. You can play with the start=00&count=10 parameters to get the results you want.
Enjoy.