d0c353609d
When an unknown content type is encountered, it's imported as a RawDescriptor, which will preserve the OLX and export it back out. But if we import a course while an XBlock is installed and then export it after that XBlock is removed, we export RawDescriptors that never got to save the original OLX and have a blank "data" field. Attempting to export this used to fail and break export altogether. We now test that the export continues to complete, and just skips over anything it can't serialize out. Note that this will stil export pointers in the export, so if you uninstalled a "AmazingBlock" and exported, you might see something like the following in a vertical's XML:: <vertical display_name="Unit"> <amazing url_name="2edebb68d5734395a06b8a62b9bb677e"/> </vertical> However there would be no corresponding file at: /amazing/2edebb68d5734395a06b8a62b9bb677e.xml In fact, there would be no /amazing directory at all in the export. The better long term solution is probably to leave the pointer as-is and export some generic file that can't be mistaken for OLX (say a JSON file) that represents the raw key-value data we have in Modulstore for the now unknown XBlock type. However, this commit at least keeps export from crashing out entirely.
82 lines
2.9 KiB
Python
82 lines
2.9 KiB
Python
import logging
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from exceptions import SerializationError
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from lxml import etree
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from xblock.fields import Scope, String
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from xmodule.editing_module import XMLEditingDescriptor
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from xmodule.xml_module import XmlDescriptor
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log = logging.getLogger(__name__)
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class RawDescriptor(XmlDescriptor, XMLEditingDescriptor):
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"""
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Module that provides a raw editing view of its data and children. It
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requires that the definition xml is valid.
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"""
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resources_dir = None
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data = String(help="XML data for the module", default="", scope=Scope.content)
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@classmethod
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def definition_from_xml(cls, xml_object, system):
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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):
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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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u"Unable to create xml for module {loc}. "
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u"Context: '{context}'"
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).format(
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context=lines[line - 1][offset - 40:offset + 40],
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loc=self.location,
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)
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raise SerializationError(self.location, msg)
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class EmptyDataRawDescriptor(XmlDescriptor, XMLEditingDescriptor):
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"""
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Version of RawDescriptor for modules which may have no XML data,
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but use XMLEditingDescriptor for import/export handling.
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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):
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if len(xml_object) == 0 and len(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):
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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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