fields: export empty list if no display locations (#89002)

tests/admin_pages/test_workflow.py

@@ -2298,6 +2298,19 @@ def test_workflows_backoffice_fields(pub):
     )
     assert 'prefill$type' not in resp.form.fields.keys()
 
+    # check display_locations
+    resp.form['display_locations$element0'] = False
+    resp.form['display_locations$element1'] = False
+    resp = resp.form.submit('submit')
+    assert (
+        resp.location
+        == 'http://example.net/backoffice/workflows/1/backoffice-fields/fields/#fieldId_%s'
+        % workflow.backoffice_fields_formdef.fields[1].id
+    )
+    resp = resp.follow()
+    workflow = Workflow.get(workflow.id)
+    assert workflow.backoffice_fields_formdef.fields[1].display_locations is None
+
     # add a title field
     resp = app.get('/backoffice/workflows/1/backoffice-fields/fields/')
     resp.forms[0]['label'] = 'foobar3'

tests/test_formdef_import.py

@@ -87,7 +87,7 @@ def test_empty_display_locations_tag(pub):
     formdef = FormDef()
     formdef.name = 'Foo'
     formdef.fields = [
-        fields.TitleField(label='title', display_locations=[]),
+        fields.TitleField(label='title', display_locations=None),
         fields.SubtitleField(label='subtitle', display_locations=[]),
         fields.TextField(label='string', display_locations=[]),
     ]

tests/test_workflow_import.py

@@ -494,9 +494,12 @@ def test_backoffice_fields(pub):
     wf = Workflow(name='bo fields')
     wf.backoffice_fields_formdef = WorkflowBackofficeFieldsFormDef(wf)
     wf.backoffice_fields_formdef.fields = [
-        StringField(id='bo1', label='1st backoffice field', varname='backoffice_blah'),
+        StringField(
+            id='bo1', label='1st backoffice field', varname='backoffice_blah', display_locations=None
+        ),
     ]
-    assert_import_export_works(wf, True)
+    wf2 = assert_import_export_works(wf)
+    assert wf2.backoffice_fields_formdef.fields[0].display_locations == []
 
 
 def test_complex_dispatch_action(pub):

wcs/fields/base.py

@@ -443,6 +443,11 @@ class Field:
                 if xml_node_text(node.find('locked')) == 'True':
                     self.prefill['locked'] = True
 
+    def display_locations_export_to_xml(self, node, include_id=False):
+        display_locations_node = ET.SubElement(node, 'display_locations')
+        for v in self.display_locations or []:
+            ET.SubElement(display_locations_node, 'item').text = force_str(v)
+
     def get_rst_view_value(self, value, indent=''):
         return indent + self.get_view_value(value)