pyceo-broken/ceo/pymazon.py

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2009-03-11 01:40:20 -04:00
#!/usr/bin/python
from xml.dom import minidom, Node
import urllib
import time
import datetime
import hashlib
import base64
import hmac
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class PyMazonError(Exception):
"""Holds information about an error that occured during a pymazon request"""
def __init__(self, messages):
self.__message = '\n'.join(messages)
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def __get_message(self):
return self.__message
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def __str__(self):
return repr(self.__message)
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message = property(fget=__get_message)
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class PyMazonBook:
"""Stores information about a book retrieved via PyMazon."""
def __init__(self, title, authors, publisher, year, isbn10, isbn13, edition):
self.__title = title
self.__authors = authors
self.__publisher = publisher
self.__year = year
self.__isbn10 = isbn10
self.__isbn13 = isbn13
self.__edition = edition
def __str__(self):
return 'Title: ' + self.title + '\n' + \
'Author(s): ' + ', '.join(self.authors) + '\n' \
'Publisher: ' + self.publisher + '\n' + \
'Year: ' + self.year + '\n' + \
'ISBN-10: ' + self.isbn10 + '\n' + \
'ISBN-13: ' + self.isbn13 + '\n' + \
'Edition: ' + self.edition
def __get_title(self):
return self.__title
def __get_authors(self):
return self.__authors
def __get_publisher(self):
return self.__publisher
def __get_year(self):
return self.__year
def __get_isbn10(self):
return self.__isbn10
def __get_isbn13(self):
return self.__isbn13
def __get_edition(self):
return self.__edition
title = property(fget=__get_title)
authors = property(fget=__get_authors)
publisher = property(fget=__get_publisher)
year = property(fget=__get_year)
isbn10 = property(fget=__get_isbn10)
isbn13 = property(fget=__get_isbn13)
edition = property(fget=__get_edition)
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class PyMazon:
"""A method of looking up book information on Amazon."""
def __init__(self, accesskey, secretkey):
self.__key = accesskey
self.__secret = secretkey
self.__last_query_time = 0
def __form_request(self, isbn):
content = {}
dstamp = datetime.datetime.utcfromtimestamp(time.time())
content['Timestamp'] = dstamp.strftime('%Y-%m-%dT%H:%M:%S.000Z')
content['Service'] = 'AWSECommerceService'
content['Version'] = '2008-08-19'
content['Operation'] = 'ItemLookup'
content['ResponseGroup'] = 'ItemAttributes'
content['IdType'] = 'ISBN'
content['SearchIndex'] = 'Books'
content['ItemId'] = isbn
content['AWSAccessKeyId'] = self.__key
URI_String = []
for key, value in sorted(content.items()):
URI_String.append('%s=%s' % (key, urllib.quote(value)))
req = '&'.join(URI_String)
to_sign_req = 'GET\necs.amazonaws.com\n/onca/xml\n' + req
h = hmac.new(self.__secret, to_sign_req, hashlib.sha256)
sig = base64.b64encode(h.digest())
req += '&Signature=%s' % urllib.quote(sig)
return 'http://ecs.amazonaws.com/onca/xml?' + req
def __elements_text(self, element, name):
result = []
matching = element.getElementsByTagName(name)
for match in matching:
if len(match.childNodes) != 1:
continue
child = match.firstChild
if child.nodeType != Node.TEXT_NODE:
continue
result.append(child.nodeValue.strip())
return result
def __format_errors(self, errors):
error_list = []
for error in errors:
error_list.extend(self.__elements_text(error, 'Message'))
return error_list
def __extract_single(self, element, name):
matches = self.__elements_text(element, name)
if len(matches) == 0:
return ''
return matches[0]
def lookup(self, isbn):
file = urllib.urlretrieve(self.__form_request(isbn))[0]
xmldoc = minidom.parse(file)
cur_time = time.time()
while cur_time - self.__last_query_time < 1.0:
sleep(cur_time - self.__last_query_time)
cur_time = time.time()
self.__last_query_time = cur_time
errors = xmldoc.getElementsByTagName('Errors')
if len(errors) != 0:
raise PyMazonError, self.__format_errors(errors)
title = self.__extract_single(xmldoc, 'Title')
authors = self.__elements_text(xmldoc, 'Author')
publisher = self.__extract_single(xmldoc, 'Publisher')
year = self.__extract_single(xmldoc, 'PublicationDate')[0:4]
isbn10 = self.__extract_single(xmldoc, 'ISBN')
isbn13 = self.__extract_single(xmldoc, 'EAN')
edition = self.__extract_single(xmldoc, 'Edition')
return PyMazonBook(title, authors, publisher, year, isbn10, isbn13, edition)