118 lines
4.2 KiB
Python
118 lines
4.2 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 xml.dom.minidom import parse, parseString
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from lxml import etree
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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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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}"]', 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 course_file(user):
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# TODO: Cache. Also, return the libxml2 object.
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return settings.DATA_DIR+UserProfile.objects.get(user=user).courseware
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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 = etree.parse(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(coursefile, active_chapter, active_section):
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dom=parse(coursefile)
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course = dom.getElementsByTagName('course')[0]
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name=course.getAttribute("name")
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chapters = course.getElementsByTagName('chapter')
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ch=list()
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for c in chapters:
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if c.getAttribute("name") == 'hidden':
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continue
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sections=list()
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for s in c.getElementsByTagName('section'):
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sections.append({'name':s.getAttribute("name"),
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'time':s.getAttribute("time"),
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'format':s.getAttribute("format"),
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'due':s.getAttribute("due"),
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'active':(c.getAttribute("name")==active_chapter and \
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s.getAttribute("name")==active_section)})
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ch.append({'name':c.getAttribute("name"),
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'sections':sections,
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'active':(c.getAttribute("name")==active_chapter)})
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return ch
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def dom_select(dom, element_type, element_name):
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if dom==None:
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return None
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elements=dom.getElementsByTagName(element_type)
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for e in elements:
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if e.getAttribute("name")==element_name:
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return e
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return None
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