forms: keep locked field as readonly on page with errors (#41411)

tests/test_form_pages.py

@@ -5307,6 +5307,34 @@ def test_form_page_profile_verified_prefill(pub):
         assert formdatas[0].data['0'] == 'foo@localhost'
 
 
+def test_form_page_verified_prefill_error_page(pub):
+    user = create_user(pub)
+    user.verified_fields = ['email']
+    user.store()
+    formdef = create_formdef()
+    formdef.data_class().wipe()
+    formdef.fields = [
+        fields.StringField(id='0', label='string', required=False),
+        fields.StringField(id='1', label='string2', required=True),
+    ]
+    formdef.store()
+
+    for prefill_settings in (
+            {'type': 'user', 'value': 'email'},  # verified profile
+            {'type': 'string', 'value': 'foo@localhost', 'locked': True},  # locked value
+        ):
+        formdef.fields[0].prefill = prefill_settings
+        formdef.store()
+        formdef.data_class().wipe()
+        resp = login(get_app(pub), username='foo', password='foo').get('/test/')
+        assert resp.form['f0'].value == 'foo@localhost'
+        assert 'readonly' in resp.form['f0'].attrs
+
+        resp = resp.form.submit('submit')
+        assert 'There were errors processing the form' in resp.text
+        assert 'readonly' in resp.form['f0'].attrs
+
+
 def test_form_page_profile_verified_date_prefill(pub):
     user = create_user(pub)
 

wcs/forms/root.py

@@ -406,6 +406,14 @@ class FormPage(Directory, FormTemplateMixin):
             else:
                 req.form = {}
 
+        else:
+            # not a page change, reset_locked_data() will have been called
+            # earlier, we use that to set appropriate fields as readonly.
+            for field in displayed_fields:
+                if get_request().form.get('__locked_f%s' % field.id):
+                    form.get_widget('f%s' % field.id).readonly = 'readonly'
+                    form.get_widget('f%s' % field.id).attrs['readonly'] = 'readonly'
+
         for field in displayed_fields:
             if field.prefill:
                 # always set additional attributes as they will be used for
@@ -969,6 +977,9 @@ class FormPage(Directory, FormTemplateMixin):
                     # submitted by the browser.
                     v = field.convert_value_to_str(v)
                 get_request().form['f%s' % field.id] = v
+                # keep track of locked field, this will be used when
+                # redisplaying the same page in case of errors.
+                get_request().form['__locked_f%s' % field.id] = True
 
     def previous_page(self, page_no, magictoken):
         session = get_session()