Feature/external instance #107

pyxform/builder.py

@@ -3,6 +3,7 @@
 
 from pyxform import file_utils, utils
 from pyxform.errors import PyXFormError
+from pyxform.external_instance import ExternalInstance
 from pyxform.question import (InputQuestion, MultipleChoiceQuestion,
                               OsmUploadQuestion, Question, RangeQuestion,
                               TriggerQuestion, UploadQuestion)
@@ -92,6 +93,8 @@ def create_survey_element_from_dict(self, d):
             d = self._sections[section_name]
             full_survey = self.create_survey_element_from_dict(d)
             return full_survey.children
+        elif d[u"type"] == u"xml-external":
+            return ExternalInstance(**d)
         else:
             return self._create_question_from_dict(
                 d, copy_json_dict(QUESTION_TYPE_DICT), self._add_none_option)

pyxform/external_instance.py

@@ -0,0 +1,13 @@
+from pyxform.survey_element import SurveyElement
+from pyxform.utils import node
+
+
+class ExternalInstance(SurveyElement):
+
+    def xml_control(self):
+        """
+        No-op since there is no associated form control to place under <body/>.
+
+        Exists here because there's a soft abstractmethod in SurveyElement.
+        """
+        pass

pyxform/instance_info.py

@@ -0,0 +1,11 @@
+
+
+class InstanceInfo(object):
+    """Standardise Instance details relevant during XML generation."""
+
+    def __init__(self, type, context, name, src, instance):
+        self.type = type
+        self.context = context
+        self.name = name
+        self.src = src
+        self.instance = instance

pyxform/question_type_dictionary.py

@@ -856,5 +856,8 @@ def generate_new_dict():
             "bind": {
                 "type": "binary"
             }
+        },
+        "xml-external": {
+            # Only effect is to add an external instance.
         }
     }

pyxform/section.py

@@ -1,3 +1,4 @@
+from pyxform.external_instance import ExternalInstance
 from pyxform.question import SurveyElement
 from pyxform.utils import node
 from pyxform.errors import PyXFormError
@@ -38,6 +39,8 @@ def xml_instance(self, **kwargs):
             if child.get(u"flat"):
                 for grandchild in child.xml_instance_array():
                     result.appendChild(grandchild)
+            elif isinstance(child, ExternalInstance):
+                continue
             else:
                 result.appendChild(child.xml_instance())
         return result