Allow export of OpenAssessmentBlock to XML

apps/openassessment/xblock/openassessmentblock.py

@@ -19,7 +19,7 @@ from openassessment.xblock.peer_assessment_mixin import PeerAssessmentMixin
 from openassessment.xblock.self_assessment_mixin import SelfAssessmentMixin
 from openassessment.xblock.submission_mixin import SubmissionMixin
 from openassessment.xblock.studio_mixin import StudioMixin
-from openassessment.xblock.xml import update_from_xml
+from openassessment.xblock.xml import update_from_xml, serialize_content_to_xml
 from openassessment.xblock.workflow_mixin import WorkflowMixin
 from openassessment.workflow import api as workflow_api
 from openassessment.xblock.validation import validator
@@ -380,6 +380,12 @@ class OpenAssessmentBlock(
         context = Context(context_dict)
         return Response(template.render(context), content_type='application/html', charset='UTF-8')
 
+    def add_xml_to_node(self, node):
+        """
+        Serialize the XBlock to XML for exporting.
+        """
+        serialize_content_to_xml(self, node)
+
     def render_error(self, error_msg):
         """
         Render an error message.

apps/openassessment/xblock/test/test_export_import.py

+"""
+Test that we can export a block from the runtime (to XML) and re-import it without error.
+"""
+
+import copy
+from StringIO import StringIO
+from .base import XBlockHandlerTestCase, scenario
+
+
+class TestExportImport(XBlockHandlerTestCase):
+
+    @scenario('data/basic_scenario.xml')
+    def test_export_import(self, xblock):
+
+        # Store the fields of the XBlock
+        old_fields = copy.deepcopy(xblock.fields)
+
+        # Export the XBlock from the runtime
+        output_buffer = StringIO()
+        self.runtime.export_to_xml(xblock, output_buffer)
+
+        # Re-import the XBlock
+        block_id = self.runtime.parse_xml_string(output_buffer.getvalue(), self.runtime.id_generator)
+        new_block = self.runtime.get_block(block_id)
+
+        # Check that the values of all fields are the same
+        self.assertItemsEqual(new_block.fields, old_fields)

apps/openassessment/xblock/xml.py

@@ -365,17 +365,19 @@ def _parse_assessments_xml(assessments_root, start, due):
     return assessments_list
 
 
-def serialize_content(oa_block):
+def serialize_content_to_xml(oa_block, root):
     """
     Serialize the OpenAssessment XBlock's content to XML.
 
     Args:
         oa_block (OpenAssessmentBlock): The open assessment block to serialize.
+        root (etree.Element): The XML root node to update.
 
     Returns:
-        xml (unicode)
+        etree.Element
+
     """
-    root = etree.Element('openassessment')
+    root.tag = 'openassessment'
 
     # Set submission due date
     if oa_block.submission_due is not None:
@@ -410,6 +412,20 @@ def serialize_content(oa_block):
     rubric_root = etree.SubElement(root, 'rubric')
     _serialize_rubric(rubric_root, oa_block)
 
+
+def serialize_content(oa_block):
+    """
+    Serialize the OpenAssessment XBlock's content to an XML string.
+
+    Args:
+        oa_block (OpenAssessmentBlock): The open assessment block to serialize.
+
+    Returns:
+        xml (unicode)
+    """
+    root = etree.Element('openassessment')
+    serialize_content_to_xml(oa_block, root)
+
     # Return a UTF-8 representation of the XML
     return etree.tostring(root, pretty_print=True, encoding='utf-8')