Export large xml as separate files. Note: inherited metadata is creeping into child nodes

common/lib/xmodule/html_module.py

-import json
 import logging
 
 from xmodule.x_module import XModule
 from xmodule.raw_module import RawDescriptor
-from lxml import etree
 from pkg_resources import resource_string
 
 log = logging.getLogger("mitx.courseware")
@@ -28,7 +26,3 @@ class HtmlDescriptor(RawDescriptor):
 
     js = {'coffee': [resource_string(__name__, 'js/module/html.coffee')]}
     js_module = 'HTML'
-
-    @classmethod
-    def definition_from_file(cls, file, system):
-        return {'data': file.read()}

common/lib/xmodule/xml_module.py

@@ -70,16 +70,6 @@ class XmlDescriptor(XModuleDescriptor):
         raise NotImplementedError("%s does not implement definition_from_xml" % cls.__name__)
 
     @classmethod
-    def definition_from_file(cls, file, system):
-        """
-        Return the definition to be passed to the newly created descriptor
-        during from_xml
-
-        file: File pointer
-        """
-        return cls.definition_from_xml(etree.parse(file), system)
-
-    @classmethod
     def from_xml(cls, xml_data, system, org=None, course=None):
         """
         Creates an instance of this descriptor from the supplied xml_data.
@@ -113,8 +103,9 @@ class XmlDescriptor(XModuleDescriptor):
             if filename is None:
                 return cls.definition_from_xml(xml_object, system)
             else:
-                filepath = '{type}/{name}.{ext}'.format(type=xml_object.tag, name=filename, ext=cls.filename_extension)
-                return cls.definition_from_file(system.resources_fs.open(filepath), system)
+                filepath = cls._format_filepath(xml_object.tag, filename)
+                with system.resources_fs.open(filepath) as file:
+                    return cls.definition_from_xml(etree.parse(file).getroot(), system)
 
         return cls(
             system,
@@ -127,6 +118,10 @@ class XmlDescriptor(XModuleDescriptor):
             metadata=LazyLoadingDict(metadata_loader),
         )
 
+    @classmethod
+    def _format_filepath(cls, type, name):
+        return '{type}/{name}.{ext}'.format(type=type, name=name, ext=cls.filename_extension)
+
     def export_to_xml(self, resource_fs):
         """
         Returns an xml string representing this module, and all modules underneath it.
@@ -139,6 +134,20 @@ class XmlDescriptor(XModuleDescriptor):
         using the from_xml method with the same system, org, and course
         """
         xml_object = self.definition_to_xml(resource_fs)
+
+        # Put content in a separate file if it's large (has more than 5 descendent tags)
+        if len(list(xml_object.iter())) > 5:
+
+            filepath = self.__class__._format_filepath(self.type, self.name)
+            resource_fs.makedir(self.type, allow_recreate=True)
+            with resource_fs.open(filepath, 'w') as file:
+                file.write(etree.tostring(xml_object, pretty_print=True))
+
+            for child in xml_object:
+                xml_object.remove(child)
+
+            xml_object.set('filename', self.name)
+
         xml_object.set('slug', self.name)
         xml_object.tag = self.type