Support choice from previous repeat answers for select_one

src/formpack/schema/fields.py

@@ -150,14 +150,22 @@ def from_json_definition(cls, definition, hierarchy=None,
 
         # normalize spaces
         data_type = definition['type']
-        choice = None
 
         if ' ' in data_type:
             raise ValueError('invalid data_type: %s' % data_type)
 
         if data_type in ('select_one', 'select_multiple'):
             choice_id = definition['select_from_list_name']
-            choice = field_choices[choice_id]
+            # pyxform#472 introduced dynamic list_names for select_one with the
+            # format of `select_one ${question_name}`. The choices are
+            # therefore not within a separate choice list
+            if choice_id.startswith('${') and choice_id.endswith('}'):
+                # ${dynamic_choice}, so question will be treated as a TextField
+                choice = None
+            else:
+                choice = field_choices[choice_id]
+        else:
+            choice = None
 
         data_type_classes = {
             # selects

tests/fixtures/select_one_from_previous_answers/__init__.py

@@ -0,0 +1,19 @@
+# coding: utf-8
+
+from __future__ import (unicode_literals, print_function,
+                        absolute_import, division)
+
+'''
+select_one_from_previous_answers
+
+'''
+
+from ..load_fixture_json import load_fixture_json
+
+DATA = {
+    'title': 'Household survey with select_one from previous answers',
+    'id_string': 'select_one_from_previous_answers',
+    'versions': [
+        load_fixture_json('select_one_from_previous_answers/v1'),
+    ],
+}

tests/fixtures/select_one_from_previous_answers/v1.json

@@ -0,0 +1,76 @@
+{
+    "version": "romev1",
+    "content": {
+	  "survey": [
+		{
+		  "name": "Q1",
+		  "type": "integer",
+		  "label": [
+			"How many members live in your family?"
+		  ]
+		},
+		{
+		  "name": "FM",
+		  "type": "begin_repeat",
+		  "label": [
+			"Family Members"
+		  ],
+		  "repeat_count": "${Q1}"
+		},
+		{
+		  "name": "Q2",
+		  "type": "text",
+		  "label": [
+			"Name?"
+		  ]
+		},
+		{
+		  "name": "Q3",
+		  "type": "integer",
+		  "label": [
+			"${Q2}'s age?"
+		  ]
+		},
+		{
+		  "type": "end_repeat"
+		},
+		{
+		  "name": "Q4",
+		  "type": "select_one",
+		  "label": [
+			"Select the head of the household."
+		  ],
+		  "select_from_list_name": "${Q2}"
+		},
+		{
+		  "name": "Q5",
+		  "type": "select_one",
+		  "label": [
+			"Select the youngest child (<18 years) who is currently available in the family."
+		  ],
+		  "choice_filter": "${Q3} < 18",
+		  "select_from_list_name": "${Q2}"
+		}
+	  ]
+    },
+	"submissions": [
+		{
+		  "FM": [
+			{
+			  "FM/Q2": "Julius Caesar",
+			  "FM/Q3": "53"
+			},
+			{
+			  "FM/Q2": "Gaius Octavius",
+			  "FM/Q3": "17"
+			}
+		  ],
+		  "FM_count": "2",
+		  "Q1": "2",
+		  "Q4": "Julius Caesar",
+		  "Q5": "Gaius Octavius",
+          "meta/versionID": "romev1",
+		  "meta/instanceID": "uuid:40805f86-2638-46f1-ab5a-72f4632474b5"
+		}
+	]
+}

tests/test_exports.py

@@ -415,6 +415,63 @@ def test_repeats(self):
                             ])
         )
 
+    def test_select_one_from_previous_answers(self):
+        title, schemas, submissions = build_fixture(
+            'select_one_from_previous_answers'
+        )
+        fp = FormPack(schemas, title)
+        options = {'versions': 'romev1'}
+        export = fp.export(**options).to_dict(submissions)
+        expected_dict = OrderedDict(
+            [
+                (
+                    'Household survey with select_one from previous answers',
+                    {
+                        'fields': [
+                            'Q1',
+                            'Q4',
+                            'Q5',
+                            '_index',
+                        ],
+                        'data': [
+                            [
+                                '2',
+                                'Julius Caesar',
+                                'Gaius Octavius',
+                                1,
+                            ]
+                        ],
+                    },
+                ),
+                (
+                    'FM',
+                    {
+                        'fields': [
+                            'Q2',
+                            'Q3',
+                            '_parent_table_name',
+                            '_parent_index',
+                        ],
+                        'data': [
+                            [
+                                'Julius Caesar',
+                                '53',
+                                'Household survey with select_one from previous answers',
+                                1,
+                            ],
+                            [
+                                'Gaius Octavius',
+                                '17',
+                                'Household survey with select_one from previous answers',
+                                1,
+                            ],
+                        ],
+                    },
+                ),
+            ]
+        )
+        self.assertEqual(export, expected_dict)
+
     def test_nested_repeats_with_copy_fields(self):
         title, schemas, submissions = build_fixture(
             'nested_grouped_repeatable')