107 lines
4.1 KiB
Python
107 lines
4.1 KiB
Python
"""Mixin classes for handling raw XML data in XBlocks."""
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import logging
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import re
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from lxml import etree
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from xblock.fields import Scope, String
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from .exceptions import SerializationError
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log = logging.getLogger(__name__)
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PRE_TAG_REGEX = re.compile(r"<pre\b[^>]*>(?:(?=([^<]+))\1|<(?!pre\b[^>]*>))*?</pre>")
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class RawMixin:
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"""
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Common code between RawDescriptor and XBlocks converted from XModules.
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"""
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resources_dir = None
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data = String(help="XML data for the block", default="", scope=Scope.content)
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@classmethod
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def definition_from_xml(cls, xml_object, system): # pylint: disable=unused-argument
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"""Convert XML node into a dictionary with 'data' key for XBlock."""
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return {"data": etree.tostring(xml_object, pretty_print=True, encoding="unicode")}, []
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def definition_to_xml(self, resource_fs): # pylint: disable=unused-argument
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"""
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Return an Element if we've kept the import OLX, or None otherwise.
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"""
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# If there's no self.data, it means that an XBlock/XModule originally
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# existed for this data at the time of import/editing, but was later
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# uninstalled. RawDescriptor therefore never got to preserve the
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# original OLX that came in, and we have no idea how it should be
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# serialized for export. It's possible that we could do some smarter
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# fallback here and attempt to extract the data, but it's reasonable
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# and simpler to just skip this node altogether.
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if not self.data:
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log.warning(
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"Could not serialize %s: No XBlock installed for '%s' tag.",
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self.location,
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self.location.block_type,
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)
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return None
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# Normal case: Just echo back the original OLX we saved.
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try:
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return etree.fromstring(self.data)
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except etree.XMLSyntaxError as err:
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# Can't recover here, so just add some info and
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# re-raise
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lines = self.data.split("\n")
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line, offset = err.position
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msg = (
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f"Unable to create xml for block {self.location}. "
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f"Context: '{lines[line - 1][offset - 40 : offset + 40]}'"
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)
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raise SerializationError(self.location, msg) from err
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@classmethod
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def parse_xml_new_runtime(cls, node, runtime, keys):
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"""
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Interpret the parsed XML in `node`, creating a new instance of this
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module.
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"""
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# In the new/learning-core-based runtime, XModule parsing (from
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# XmlMixin) is disabled, so definition_from_xml will not be
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# called, and instead the "normal" XBlock parse_xml will be used.
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# However, it's not compatible with RawMixin, so we implement
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# support here.
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data_field_value = cls.definition_from_xml(node, None)[0]["data"]
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for child in node.getchildren():
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node.remove(child)
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# Get attributes, if any, via normal parse_xml.
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try:
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block = super().parse_xml_new_runtime(node, runtime, keys)
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except AttributeError:
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block = super().parse_xml(node, runtime, keys)
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block.data = data_field_value
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return block
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class EmptyDataRawMixin:
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"""
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Common code between EmptyDataRawDescriptor and XBlocks converted from XModules.
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"""
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resources_dir = None
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data = String(default="", scope=Scope.content)
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@classmethod
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def definition_from_xml(cls, xml_object, system): # pylint: disable=unused-argument
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"""Convert XML node to dictionary with 'data', handling empty nodes specially."""
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if len(xml_object) == 0 and len(list(xml_object.items())) == 0:
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return {"data": ""}, []
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return {"data": etree.tostring(xml_object, pretty_print=True, encoding="unicode")}, []
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def definition_to_xml(self, resource_fs): # pylint: disable=unused-argument
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"""Return an XML Element from stored data, or an empty element if data is empty."""
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if self.data:
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return etree.fromstring(self.data)
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return etree.Element(self.category)
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