admin: include prefixed-varname when displaying a single page (#16979)

tests/test_admin_pages.py

@@ -1157,6 +1157,27 @@ def test_form_edit_map_field(pub):
     resp = resp.form.submit('submit')
     assert 'widget-with-error' in resp.body
 
+def test_form_limit_display_to_page(pub):
+    create_superuser(pub)
+    create_role()
+
+    FormDef.wipe()
+    formdef = FormDef()
+    formdef.name = 'form title'
+    formdef.fields = [fields.PageField(id='0', label='1st page', type='page'),
+            fields.StringField(id='1', label='string', varname='foobar'),
+            fields.PageField(id='2', label='2nd page', type='page'),
+            fields.StringField(id='3', label='string 2')]
+    formdef.store()
+
+    app = login(get_app(pub))
+    resp = app.get('/backoffice/forms/1/fields/')
+    assert '[form_var_foobar]' in resp.body
+    assert '2nd page' in resp.body
+    resp = resp.click('Limit display to this page', index=0)
+    assert '[form_var_foobar]' in resp.body
+    assert 'Display all pages' in resp.body
+
 def test_form_legacy_int_id(pub):
     create_superuser(pub)
     create_role()

wcs/admin/fields.py

@@ -158,6 +158,7 @@ class FieldsPagesDirectory(Directory):
 
     def _q_lookup(self, component):
         directory = FieldsDirectory(self.parent.objectdef)
+        directory.field_var_prefix = self.parent.field_var_prefix
         directory.html_top = self.parent.html_top
         try:
             directory.page_no = int(component)