from collections import defaultdict from lxml import etree from lxml import objectify from lxml.etree import QName from .utils import InvalidLTIConfigError VALID_ATTRIBUTES = [ 'title', 'description', 'launch_url', 'secure_launch_url', 'icon', 'secure_icon', 'cartridge_bundle', 'cartridge_icon', 'vendor_code', 'vendor_name', 'vendor_description', 'vendor_url', 'vendor_contact_email', 'vendor_contact_name' ] NSMAP = { 'blti': 'http://www.imsglobal.org/xsd/imsbasiclti_v1p0', 'lticm': 'http://www.imsglobal.org/xsd/imslticm_v1p0', 'lticp': 'http://www.imsglobal.org/xsd/imslticp_v1p0', 'xsi': "http://www.w3.org/2001/XMLSchema-instance", } class ToolConfig(object): ''' Object used to represent LTI configuration. Capable of creating and reading the Common Cartridge XML representation of LTI links as described here: http://www.imsglobal.org/LTI/v1p1/ltiIMGv1p1.html#_Toc319560470 TODO: Usage description ''' def __init__(self, **kwargs): ''' Create a new ToolConfig with the given options. ''' # Initialize all class accessors to None for attr in VALID_ATTRIBUTES: setattr(self, attr, None) for attr in ['custom_params', 'extensions']: if attr in kwargs: attr_val = kwargs.pop(attr) else: attr_val = defaultdict(lambda: None) setattr(self, attr, attr_val) # Iterate over all provided options and save to class instance members for (key, val) in kwargs.items(): if key in VALID_ATTRIBUTES: setattr(self, key, val) else: raise InvalidLTIConfigError( "Invalid outcome request option: {}".format(key) ) @staticmethod def create_from_xml(xml): ''' Create a ToolConfig from the given XML. ''' config = ToolConfig() config.process_xml(xml) return config def set_custom_param(self, key, val): ''' Set a custom parameter to provided value. ''' self.custom_params[key] = val def get_custom_param(self, key): ''' Gets a custom parameter. It not yet set, returns None object. ''' return self.custom_params[key] def set_ext_params(self, ext_key, ext_params): ''' Set the extension parameters for a specific vendor. ''' self.extensions[ext_key] = ext_params def get_ext_params(self, ext_key): ''' Get extension paramaters for provided extension. It not set, returns None object. ''' return self.extensions[ext_key] def set_ext_param(self, ext_key, param_key, val): ''' Set the provided parameter in a set of extension parameters. ''' self.extensions.setdefault(ext_key, defaultdict(lambda: None)) self.extensions[ext_key][param_key] = val def get_ext_param(self, ext_key, param_key): ''' Get specific param in set of provided extension parameters. ''' if ext_key in self.extensions: return self.extensions[ext_key].get(param_key) def process_xml(self, xml): ''' Parse tool configuration data out of the Common Cartridge LTI link XML. ''' root = objectify.fromstring(xml, parser=etree.XMLParser()) # Parse all children of the root node for child in root.getchildren(): if QName(child).localname == 'title': self.title = child.text if QName(child).localname == 'description': self.description = child.text if QName(child).localname == 'secure_launch_url': self.secure_launch_url = child.text if QName(child).localname == 'launch_url': self.launch_url = child.text if QName(child).localname == 'icon': self.icon = child.text if QName(child).localname == 'secure_icon': self.secure_icon = child.text if QName(child).localname == 'cartridge_bundle': self.cartridge_bundle = child.attrib['identifierref'] if QName(child).localname == 'cartridge_icon': self.cartridge_icon = child.attrib['identifierref'] if QName(child).localname == 'vendor': # Parse vendor tag for v_child in child.getchildren(): if QName(v_child).localname == 'code': self.vendor_code = v_child.text if QName(v_child).localname == 'description': self.vendor_description = v_child.text if QName(v_child).localname == 'name': self.vendor_name = v_child.text if QName(v_child).localname == 'url': self.vendor_url = v_child.text if QName(v_child).localname == 'contact': # Parse contact tag for email and name for c_child in v_child: if QName(c_child).localname == 'name': self.vendor_contact_name = c_child.text if QName(c_child).localname == 'email': self.vendor_contact_email = c_child.text if QName(child).localname == 'custom': # Parse custom tags for custom_child in child.getchildren(): self.custom_params[custom_child.attrib['name']] =\ custom_child.text if QName(child).localname == 'extensions': platform = child.attrib['platform'] properties = {} # Parse extension tags for ext_child in child.getchildren(): if QName(ext_child).localname == 'property': properties[ext_child.attrib['name']] = ext_child.text elif QName(ext_child).localname == 'options': opt_name = ext_child.attrib['name'] options = {} for option_child in ext_child.getchildren(): options[option_child.attrib['name']] =\ option_child.text properties[opt_name] = options self.set_ext_params(platform, properties) def recursive_options(self, element, params): for key, val in sorted(params.items()): if isinstance(val, dict): options_node = etree.SubElement( element, '{%s}%s' % (NSMAP['lticm'], 'options'), name=key, ) for key, val in sorted(val.items()): self.recursive_options(options_node, {key: val}) else: param_node = etree.SubElement( element, '{%s}%s' % (NSMAP['lticm'], 'property'), name=key, ) param_node.text = val def to_xml(self, opts=defaultdict(lambda: None)): ''' Generate XML from the current settings. ''' if not self.launch_url or not self.secure_launch_url: raise InvalidLTIConfigError('Invalid LTI configuration') root = etree.Element( 'cartridge_basiclti_link', attrib={ '{%s}%s' % (NSMAP['xsi'], 'schemaLocation'): 'http://www.imsglobal.org/xsd/imslticc_v1p0 http://www.imsglobal.org/xsd/lti/ltiv1p0/imslticc_v1p0.xsd http://www.imsglobal.org/xsd/imsbasiclti_v1p0 http://www.imsglobal.org/xsd/lti/ltiv1p0/imsbasiclti_v1p0p1.xsd http://www.imsglobal.org/xsd/imslticm_v1p0 http://www.imsglobal.org/xsd/lti/ltiv1p0/imslticm_v1p0.xsd http://www.imsglobal.org/xsd/imslticp_v1p0 http://www.imsglobal.org/xsd/lti/ltiv1p0/imslticp_v1p0.xsd', 'xmlns': 'http://www.imsglobal.org/xsd/imslticc_v1p0', }, nsmap=NSMAP, ) for key in ['title', 'description', 'launch_url', 'secure_launch_url']: option = etree.SubElement(root, '{%s}%s' % (NSMAP['blti'], key)) option.text = getattr(self, key) if getattr(self, 'icon'): option = etree.SubElement(root, '{%s}%s' % (NSMAP['blti'], 'icon')) option.text = getattr(self, 'icon') if getattr(self, 'secure_icon'): option = etree.SubElement(root, '{%s}%s' % (NSMAP['blti'], 'secure_icon')) option.text = getattr(self, 'secure_icon') vendor_keys = ['name', 'code', 'description', 'url'] if any('vendor_' + key for key in vendor_keys) or\ self.vendor_contact_email: vendor_node = etree.SubElement( root, '{%s}%s' % (NSMAP['blti'], 'vendor'), ) for key in vendor_keys: if getattr(self, 'vendor_' + key) is not None: v_node = etree.SubElement( vendor_node, '{%s}%s' % (NSMAP['lticp'], key), ) v_node.text = getattr(self, 'vendor_' + key) if getattr(self, 'vendor_contact_email'): v_node = etree.SubElement( vendor_node, '{%s}%s' % (NSMAP['lticp'], 'contact'), ) c_name = etree.SubElement( v_node, '{%s}%s' % (NSMAP['lticp'], 'name'), ) c_name.text = self.vendor_contact_name c_email = etree.SubElement( v_node, '{%s}%s' % (NSMAP['lticp'], 'email'), ) c_email.text = self.vendor_contact_email # Custom params if len(self.custom_params) != 0: custom_node = etree.SubElement( root, '{%s}%s' % (NSMAP['blti'], 'custom'), ) for (key, val) in sorted(self.custom_params.items()): c_node = etree.SubElement( custom_node, '{%s}%s' % (NSMAP['lticm'], 'property'), ) c_node.set('name', key) c_node.text = val # Extension params if len(self.extensions) != 0: for (key, params) in sorted(self.extensions.items()): extension_node = etree.SubElement( root, '{%s}%s' % (NSMAP['blti'], 'extensions'), platform=key, ) self.recursive_options(extension_node, params) if getattr(self, 'cartridge_bundle'): identifierref = etree.SubElement( root, 'cartridge_bundle', identifierref=self.cartridge_bundle, ) if getattr(self, 'cartridge_icon'): identifierref = etree.SubElement( root, 'cartridge_icon', identifierref=self.cartridge_icon, ) declaration = b'' return declaration + etree.tostring(root, encoding='utf-8')