forms: don't mark missing fields for live conditions (#34502)

tests/test_form_pages.py

@@ -6625,3 +6625,43 @@ def test_frontoffice_workflow_form_with_dynamic_comment(pub):
     live_resp = app.post(live_url, params=resp.form.submit_fields())
     assert live_resp.json['result']['2']['visible']
     assert live_resp.json['result']['2']['content'] == '<p>value is test</p>'
+
+def test_frontoffice_workflow_form_with_impossible_condition(pub):
+    user = create_user(pub)
+    wf = Workflow.get_default_workflow()
+    wf.id = '2'
+    wf.store()
+    wf = Workflow.get(wf.id)
+    status = wf.get_status('new')
+    status.items = []
+    display_form = FormWorkflowStatusItem()
+    display_form.id = '_display_form'
+    display_form.by = ['_submitter']
+    display_form.varname = 'blah'
+    display_form.formdef = WorkflowFormFieldsFormDef(item=display_form)
+    display_form.formdef.fields = [
+            fields.StringField(id='1', label='Test', varname='str', type='string',
+                condition={'type': 'django', 'value': '0 == 1'}),
+            fields.StringField(id='2', label='Test2', type='string',
+                condition={'type': 'django', 'value': 'blah_var_str == "toto"'}),
+    ]
+    status.items.append(display_form)
+    display_form.parent = status
+
+    wf.store()
+    formdef = create_formdef()
+    formdef.workflow_id = wf.id
+    formdef.fields = []
+    formdef.store()
+
+    formdef.data_class().wipe()
+
+    formdata = formdef.data_class()()
+    formdata.user_id = user.id
+    formdata.status = 'wf-new'
+    formdata.store()
+
+    app = login(get_app(pub), username='foo', password='foo')
+    resp = app.get(formdata.get_url(backoffice=False))
+    assert 'f1' not in resp.form.fields
+    assert resp.html.find('div', {'data-field-id': '2'}).attrs.get('style') == 'display: none'

wcs/formdef.py

@@ -658,7 +658,9 @@ class FormDef(StorableObject):
 
         for field in fields:
             if field.varname in live_condition_fields:
-                form.get_widget('f%s' % field.id).live_condition_source = True
+                widget = form.get_widget('f%s' % field.id)
+                if widget:
+                    widget.live_condition_source = True
 
     def get_field_data(self, field, widget):
         d = {}