temp: continue

xmodule/modulestore/split_mongo/caching_descriptor_system.py

@@ -218,10 +218,15 @@ class CachingDescriptorSystem(MakoDescriptorSystem, EditInfoRuntimeMixin):  # li
         Services are objects implementing arbitrary other interfaces.
         """
         # Implement field data service:
-        if service_name == "field-data":
+        if service_name in ('field-data', 'field-data-unbound'):
+            if hasattr(block, "_bound_field_data") and service_name != "field-data-unbound":
+                # Return the user-specific wrapped field data that gets set onto the block during XModule.bind_for_user
+                # This complexity is due to XModule heritage. If we didn't load the block as one step, then sometimes
+                # "rebind" it to be user-specific as a later step, we could load the field data and overrides at once.
+                return block._bound_field_data  # pylint: disable=protected-access
             if block.scope_ids not in self.block_field_datas:
                 try:
-                    self.block_field_datas[block.scope_ids] = self._init_field_data_for_block(block)
+                    self._init_field_data_for_block(block)
                 except:
                     # Don't try again pointlessly every time another field is accessed
                     self.block_field_datas[block.scope_ids] = None
@@ -295,9 +300,17 @@ class CachingDescriptorSystem(MakoDescriptorSystem, EditInfoRuntimeMixin):  # li
         else:
             field_data = KvsFieldData(kvs)
 
+        # Save the field_data now, because some of the wrappers will try to read fields from the block while they
+        # determine if they want to wrap the field_data or not.
+        self.block_field_datas[block.scope_ids] = field_data
+        # Now add in any wrappers that want to be added:
         for wrapper in self.modulestore.xblock_field_data_wrappers:
-            field_data = wrapper(block, field_data)
-        return field_data
+            self.block_field_datas[block.scope_ids] = wrapper(block, self.block_field_datas[block.scope_ids])
+
+        # Note: user-specific wrappers like LmsFieldData or OverrideFieldData do not get set here. They get set later
+        # during bind_for_student(), which wraps the field-data and sets block._bound_field_data. Calling
+        # runtime.service(block, "field-data") or block._field_data (deprecated) will load block._bound_field_data if
+        # the block has been bound to a user, otherwise it returns the wrapped field data we just created above.
 
     def get_edited_by(self, xblock):
         """

xmodule/x_module.py

@@ -10,7 +10,6 @@ from functools import partial
 import yaml
 
 from django.conf import settings
-from lazy import lazy
 from lxml import etree
 from opaque_keys.edx.asides import AsideDefinitionKeyV2, AsideUsageKeyV2
 from opaque_keys.edx.keys import UsageKey
@@ -417,13 +416,12 @@ class XModuleMixin(XModuleFields, XBlock):
         self.save()
         return self._field_data._kvs  # pylint: disable=protected-access
 
-    @lazy
     def _unwrapped_field_data(self):
         """
-        This property hold the value _field_data here before we wrap it in
-        the LmsFieldData or OverrideFieldData classes.
+        This property gets the field-data service before we wrap it in user-specifc wrappers during bind_for_student,
+        e.g. the LmsFieldData or OverrideFieldData classes.
         """
-        return self._field_data
+        return self.runtime.service(self, 'field-data-unbound')
 
     def add_aside(self, aside):
         """
@@ -653,12 +651,13 @@ class XModuleMixin(XModuleFields, XBlock):
 
         if wrappers is None:
             wrappers = []
-
-        wrapped_field_data = self._unwrapped_field_data
-        for wrapper in wrappers:
-            wrapped_field_data = wrapper(wrapped_field_data)
-
-        self._field_data = wrapped_field_data
+        if wrappers:
+            # Put user-specific wrappers around the field-data service for this block.
+            # Note that these are different from modulestore.xblock_field_data_wrappers, which are not user-specific.
+            wrapped_field_data = self.runtime.service(self, 'field-data-unbound')
+            for wrapper in wrappers:
+                wrapped_field_data = wrapper(wrapped_field_data)
+            self._bound_field_data = wrapped_field_data
 
     @property
     def non_editable_metadata_fields(self):