173 lines
6.3 KiB
Python
173 lines
6.3 KiB
Python
try:
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from django.conf import settings
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from auth.models import UserProfile
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except:
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settings = None
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from lxml import etree
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import json
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import hashlib
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import logging
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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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log = logging.getLogger("mitx.courseware")
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def fasthash(string):
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m = hashlib.new("md4")
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m.update(string)
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return "id"+m.hexdigest()
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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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default_ids = {'video':'youtube',
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'problem':'filename',
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'sequential':'id',
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'html':'filename',
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'vertical':'id',
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'tab':'id',
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'schematic':'id'}
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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]) # Convert to alphanumeric
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new_id = "".join([a for a in new_id if a.isalnum()])
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elem.set('id', new_id)
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else:
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elem.set('id', fasthash(etree.tostring(elem)))
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def due_tag(course):
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# The primary purpose of this tagging is to make sure that each problem
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# inherits the due date from the section that it is in. We also make
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# sure that each section has a due date. If it does not, it inherits
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# the last section's due date. This is to make sure that the sections
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# are in chronological order. It is an exception to have a later section
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# due before an earlier one.
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# How are due dates handled for different time zones? What _time_ are things due?
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# First, we grab the first due date to occur. This is our starting date.
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firstSectionDue = course.xpath("//section[@due]")[0]
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# I tried adding [1] to the end of the query string to select the first,
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# but it didn't work. Is this not supported in etree?
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# All new dates must be further than currentDate
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currentDate = firstSectionDue.get('due')
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sections = course.xpath("//section")
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for section in sections:
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existingDate = section.get('due')
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if existingDate:
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#TODO: Make sure existing date is further into the future than currentDate
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currentDate = existingDate
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else:
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section.set('due', currentDate)
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problems=course.xpath('//section[@name=$section]//problem', section=section.get('name'))
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for problem in problems:
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problem.set('due', currentDate)
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def course_file(user):
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# TODO: Cache.
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tree = etree.parse(settings.DATA_DIR+UserProfile.objects.get(user=user).courseware)
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id_tag(tree)
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due_tag(tree)
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return tree
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def module_xml(coursefile, module, id_tag, module_id):
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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.. '''
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doc = coursefile
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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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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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result_set=doc.xpath(xpath_search)
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if len(result_set)>1:
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print "WARNING: Potentially malformed course file", module, module_id
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if len(result_set)==0:
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return None
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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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'time':s.get("time") or "",
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'format':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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