misc: don't crash restoring unset table with rows field (#32424)

tests/test_form_pages.py

@@ -2708,6 +2708,48 @@ def test_form_table_rows_field_submit(pub, emails):
     assert 'The form has been recorded' in resp.body
     assert 'ee' in emails.emails['New form (test)']['msg'].get_payload()[1].get_payload()
 
+def test_form_new_table_rows_field_draft_recall(pub):
+    formdef = create_formdef()
+    formdef.enable_tracking_codes = True
+    formdef.fields = [
+        fields.PageField(id='0', label='1st page', type='page'),
+        fields.StringField(id='1', label='string'),
+        fields.PageField(id='2', label='2nd page', type='page'),
+    ]
+    formdef.store()
+    formdef.data_class().wipe()
+
+    formdef.store()
+
+    app = get_app(pub)
+    resp = app.get('/test/')
+    resp.form['f1'] = 'test'
+    resp = resp.form.submit('submit')
+    resp = resp.form.submit('submit')
+    assert 'Check values then click submit.' in resp.body
+    tracking_code = get_displayed_tracking_code(resp)
+    assert tracking_code is not None
+
+    # add new table rows field to formdef
+    formdef.fields.append(
+        fields.TableRowsField(id='3', label='table', type='tablerows',
+            columns=['a', 'b'], required=False)
+    )
+    formdef.store()
+
+    # restore form on validation page
+    resp = get_app(pub).get('/')
+    resp.form['code'] = tracking_code
+    resp = resp.form.submit().follow().follow().follow()
+
+    # validate form
+    resp = resp.forms[1].submit()
+    resp = resp.follow()
+    assert 'The form has been recorded' in resp.body
+    assert formdef.data_class().count() == 1
+    assert formdef.data_class().select()[0].data['1'] == 'test'
+    assert formdef.data_class().select()[0].data['3'] is None
+
 def test_formdata_attachment_download(pub):
     create_user(pub)
     wf = Workflow(name='status')

wcs/formdef.py

@@ -620,7 +620,7 @@ class FormDef(StorableObject):
                 continue
 
             current_page_fields.append(field)
-            value = dict.get(field.id, '')
+            value = dict.get(field.id)
             field.add_to_view_form(form, value)
 
         if on_page: