Moving LMS code into subdirectory
This commit is contained in:
Calen Pennington
308
lms/djangoapps/courseware/content_parser.py
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308
lms/djangoapps/courseware/content_parser.py
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'''
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courseware/content_parser.py
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This file interfaces between all courseware modules and the top-level course.xml file for a course.
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Does some caching (to be explained).
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'''
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import logging
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import os
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import re
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import sys
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import urllib
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from datetime import timedelta
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from lxml import etree
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from util.memcache import fasthash
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try: # This lets us do __name__ == ='__main__'
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from django.conf import settings
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from student.models import UserProfile
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from student.models import UserTestGroup
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from mitxmako.shortcuts import render_to_string
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from util.cache import cache
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from multicourse import multicourse_settings
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except:
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print "Could not import/content_parser"
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settings = None
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''' This file will eventually form an abstraction layer between the
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course XML file and the rest of the system.
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TODO: Shift everything from xml.dom.minidom to XPath (or XQuery)
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'''
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class ContentException(Exception):
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pass
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log = logging.getLogger("mitx.courseware")
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timedelta_regex = re.compile(r'^((?P<days>\d+?) day(?:s?))?(\s)?((?P<hours>\d+?) hour(?:s?))?(\s)?((?P<minutes>\d+?) minute(?:s)?)?(\s)?((?P<seconds>\d+?) second(?:s)?)?$')
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def format_url_params(params):
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return [ urllib.quote(string.replace(' ','_')) for string in params ]
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def parse_timedelta(time_str):
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parts = timedelta_regex.match(time_str)
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if not parts:
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return
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parts = parts.groupdict()
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time_params = {}
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for (name, param) in parts.iteritems():
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if param:
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time_params[name] = int(param)
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return timedelta(**time_params)
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def xpath(xml, query_string, **args):
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''' Safe xpath query into an xml tree:
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* xml is the tree.
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* query_string is the query
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* args are the parameters. Substitute for {params}.
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We should remove this with the move to lxml.
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We should also use lxml argument passing. '''
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doc = etree.fromstring(xml)
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#print type(doc)
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def escape(x):
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# TODO: This should escape the string. For now, we just assume it's made of valid characters.
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# Couldn't figure out how to escape for lxml in a few quick Googles
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valid_chars="".join(map(chr, range(ord('a'),ord('z')+1)+range(ord('A'),ord('Z')+1)+range(ord('0'), ord('9')+1)))+"_ "
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for e in x:
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if e not in valid_chars:
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raise Exception("Invalid char in xpath expression. TODO: Escape")
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return x
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args=dict( ((k, escape(args[k])) for k in args) )
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#print args
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results = doc.xpath(query_string.format(**args))
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return results
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def xpath_remove(tree, path):
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''' Remove all items matching path from lxml tree. Works in
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place.'''
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items = tree.xpath(path)
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for item in items:
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item.getparent().remove(item)
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return tree
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if __name__=='__main__':
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print xpath('<html><problem name="Bob"></problem></html>', '/{search}/problem[@name="{name}"]',
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search='html', name="Bob")
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def item(l, default="", process=lambda x:x):
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if len(l)==0:
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return default
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elif len(l)==1:
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return process(l[0])
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else:
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raise Exception('Malformed XML')
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def id_tag(course):
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''' Tag all course elements with unique IDs '''
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import courseware.modules
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default_ids = courseware.modules.get_default_ids()
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# Tag elements with unique IDs
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elements = course.xpath("|".join(['//'+c for c in default_ids]))
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for elem in elements:
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if elem.get('id'):
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pass
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elif elem.get(default_ids[elem.tag]):
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new_id = elem.get(default_ids[elem.tag])
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new_id = "".join([a for a in new_id if a.isalnum()]) # Convert to alphanumeric
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# Without this, a conflict may occur between an hmtl or youtube id
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new_id = default_ids[elem.tag] + new_id
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elem.set('id', new_id)
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else:
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elem.set('id', "id"+fasthash(etree.tostring(elem)))
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def propogate_downward_tag(element, attribute_name, parent_attribute = None):
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''' This call is to pass down an attribute to all children. If an element
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has this attribute, it will be "inherited" by all of its children. If a
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child (A) already has that attribute, A will keep the same attribute and
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all of A's children will inherit A's attribute. This is a recursive call.'''
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if (parent_attribute is None): #This is the entry call. Select all elements with this attribute
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all_attributed_elements = element.xpath("//*[@" + attribute_name +"]")
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for attributed_element in all_attributed_elements:
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attribute_value = attributed_element.get(attribute_name)
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for child_element in attributed_element:
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propogate_downward_tag(child_element, attribute_name, attribute_value)
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else:
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'''The hack below is because we would get _ContentOnlyELements from the
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iterator that can't have attributes set. We can't find API for it. If we
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ever have an element which subclasses BaseElement, we will not tag it'''
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if not element.get(attribute_name) and type(element) == etree._Element:
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element.set(attribute_name, parent_attribute)
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for child_element in element:
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propogate_downward_tag(child_element, attribute_name, parent_attribute)
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else:
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#This element would have already been found by Xpath, so we return
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#for now and trust that this element will get its turn to propogate
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#to its children later.
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return
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def user_groups(user):
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if not user.is_authenticated():
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return []
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# TODO: Rewrite in Django
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key = 'user_group_names_{user.id}'.format(user=user)
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cache_expiration = 60 * 60 # one hour
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# Kill caching on dev machines -- we switch groups a lot
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group_names = cache.get(key)
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if group_names is None:
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group_names = [u.name for u in UserTestGroup.objects.filter(users=user)]
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cache.set(key, group_names, cache_expiration)
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return group_names
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# return [u.name for u in UserTestGroup.objects.raw("select * from auth_user, student_usertestgroup, student_usertestgroup_users where auth_user.id = student_usertestgroup_users.user_id and student_usertestgroup_users.usertestgroup_id = student_usertestgroup.id and auth_user.id = %s", [user.id])]
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def course_xml_process(tree):
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''' Do basic pre-processing of an XML tree. Assign IDs to all
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items without. Propagate due dates, grace periods, etc. to child
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items.
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'''
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id_tag(tree)
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propogate_downward_tag(tree, "due")
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propogate_downward_tag(tree, "graded")
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propogate_downward_tag(tree, "graceperiod")
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propogate_downward_tag(tree, "showanswer")
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propogate_downward_tag(tree, "rerandomize")
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return tree
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def course_file(user,coursename=None):
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''' Given a user, return course.xml'''
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if user.is_authenticated():
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filename = UserProfile.objects.get(user=user).courseware # user.profile_cache.courseware
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else:
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filename = 'guest_course.xml'
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# if a specific course is specified, then use multicourse to get the right path to the course XML directory
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if coursename and settings.ENABLE_MULTICOURSE:
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xp = multicourse_settings.get_course_xmlpath(coursename)
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filename = xp + filename # prefix the filename with the path
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groups = user_groups(user)
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options = {'dev_content':settings.DEV_CONTENT,
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'groups' : groups}
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cache_key = filename + "_processed?dev_content:" + str(options['dev_content']) + "&groups:" + str(sorted(groups))
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if "dev" not in settings.DEFAULT_GROUPS:
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tree_string = cache.get(cache_key)
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else:
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tree_string = None
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if settings.DEBUG:
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log.info('[courseware.content_parser.course_file] filename=%s, cache_key=%s' % (filename,cache_key))
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# print '[courseware.content_parser.course_file] tree_string = ',tree_string
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if not tree_string:
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tree = course_xml_process(etree.XML(render_to_string(filename, options, namespace = 'course')))
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tree_string = etree.tostring(tree)
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cache.set(cache_key, tree_string, 60)
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else:
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tree = etree.XML(tree_string)
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return tree
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def section_file(user, section, coursename=None, dironly=False):
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'''
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Given a user and the name of a section, return that section.
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This is done specific to each course.
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If dironly=True then return the sections directory.
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TODO: This is a bit weird; dironly should be scrapped.
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'''
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filename = section+".xml"
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# if a specific course is specified, then use multicourse to get the right path to the course XML directory
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xp = ''
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if coursename and settings.ENABLE_MULTICOURSE: xp = multicourse_settings.get_course_xmlpath(coursename)
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dirname = settings.DATA_DIR + xp + '/sections/'
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if dironly: return dirname
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if filename not in os.listdir(dirname):
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log.error(filename+" not in "+str(os.listdir(dirname)))
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return None
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options = {'dev_content':settings.DEV_CONTENT,
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'groups' : user_groups(user)}
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tree = course_xml_process(etree.XML(render_to_string(filename, options, namespace = 'sections')))
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return tree
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def module_xml(user, module, id_tag, module_id, coursename=None):
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''' Get XML for a module based on module and module_id. Assumes
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module occurs once in courseware XML file or hidden section. '''
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# Sanitize input
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if not module.isalnum():
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raise Exception("Module is not alphanumeric")
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if not module_id.isalnum():
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raise Exception("Module ID is not alphanumeric")
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# Generate search
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xpath_search='//{module}[(@{id_tag} = "{id}") or (@id = "{id}")]'.format(module=module,
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id_tag=id_tag,
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id=module_id)
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#result_set=doc.xpathEval(xpath_search)
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doc = course_file(user,coursename)
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sdirname = section_file(user,'',coursename,True) # get directory where sections information is stored
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section_list = (s[:-4] for s in os.listdir(sdirname) if s[-4:]=='.xml')
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result_set=doc.xpath(xpath_search)
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if len(result_set)<1:
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for section in section_list:
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try:
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s = section_file(user, section, coursename)
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except etree.XMLSyntaxError:
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ex= sys.exc_info()
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raise ContentException("Malformed XML in " + section+ "("+str(ex[1].msg)+")")
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result_set = s.xpath(xpath_search)
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if len(result_set) != 0:
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break
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if len(result_set)>1:
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log.error("WARNING: Potentially malformed course file", module, module_id)
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if len(result_set)==0:
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if settings.DEBUG:
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log.error('[courseware.content_parser.module_xml] cannot find %s in course.xml tree' % xpath_search)
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log.error('tree = %s' % etree.tostring(doc,pretty_print=True))
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return None
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if settings.DEBUG:
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log.info('[courseware.content_parser.module_xml] found %s' % result_set)
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return etree.tostring(result_set[0])
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#return result_set[0].serialize()
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def toc_from_xml(dom, active_chapter, active_section):
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name = dom.xpath('//course/@name')[0]
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chapters = dom.xpath('//course[@name=$name]/chapter', name=name)
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ch=list()
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for c in chapters:
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if c.get('name') == 'hidden':
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continue
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sections=list()
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for s in dom.xpath('//course[@name=$name]/chapter[@name=$chname]/section', name=name, chname=c.get('name')):
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sections.append({'name':s.get("name") or "",
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'format':s.get("subtitle") if s.get("subtitle") else s.get("format") or "",
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'due':s.get("due") or "",
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'active':(c.get("name")==active_chapter and \
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s.get("name")==active_section)})
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ch.append({'name':c.get("name"),
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'sections':sections,
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'active':(c.get("name")==active_chapter)})
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return ch
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