admin: warn if a form contains more than 500 fields (#20963)

tests/test_admin_pages.py

@@ -1249,6 +1249,40 @@ def test_form_edit_map_field(pub):
     resp = resp.form.submit('submit')
     assert 'widget-with-error' in resp.body
 
+def test_form_edit_field_warnings(pub):
+    create_superuser(pub)
+    create_role()
+
+    FormDef.wipe()
+    formdef = FormDef()
+    formdef.name = 'form title'
+    formdef.fields = [fields.StringField(id='%d' % i, label='field %d' % i, type='string')
+                      for i in range(1,10)]
+    formdef.store()
+
+    app = login(get_app(pub))
+    resp = app.get('/backoffice/forms/1/')
+    resp = resp.click(href='fields/')
+    assert 'more than 500 fields' not in resp.body
+    assert 'first field should be of type "page"' not in resp.body
+
+    formdef.fields.append(fields.PageField(id='1000', label='page', type='page'))
+    formdef.store()
+    resp = app.get('/backoffice/forms/1/')
+    resp = resp.click(href='fields/')
+    assert 'more than 500 fields' not in resp.body
+    assert 'first field should be of type "page"' in resp.body
+
+    formdef.fields.extend([fields.StringField(id='%d' % i, label='field %d' % i, type='string')
+                      for i in range(10,510)])
+    formdef.store()
+    resp = app.get('/backoffice/forms/1/')
+    resp = resp.click(href='fields/')
+    assert 'more than 500 fields' in resp.body
+    assert 'first field should be of type "page"' in resp.body
+
+    FormDef.wipe()
+
 def test_form_limit_display_to_page(pub):
     create_superuser(pub)
     create_role()

wcs/admin/fields.py

@@ -202,6 +202,12 @@ class FieldsDirectory(Directory):
         r += self.index_top()
 
         if self.objectdef.fields:
+            if len(self.objectdef.fields) > 500:
+                r += htmltext('<div class="errornotice">')
+                r += htmltext(_('This form contains more than 500 fields. '
+                                'It is close to the database limits and no new fields should be added.'))
+                r += htmltext('</div>')
+
             if [x for x in self.objectdef.fields if x.type == 'page']:
                 if self.objectdef.fields[0].type != 'page':
                     r += htmltext('<div class="errornotice">')