ProxyField: make it possible to repair broken proxy fields

There have been a regression recently

bt5/erp5_core_test/TestTemplateItem/portal_components/test.erp5.testProxyField.py

@@ -398,9 +398,9 @@ return printed
         'Base_viewGeek',
         'View')
     form = skin_folder._getOb('Base_viewGeek', None)
-    form.manage_addField('my_title', 'Title', 'ProxyField')
+    form.manage_addField('my_proxy_field', 'Proxy', 'ProxyField')
 
-    field = form.my_title
+    field = form.my_proxy_field
 
     self.assertFalse(form.get_fields())
     self.assertEqual([field], form.get_fields(include_disabled=True))
@@ -409,10 +409,22 @@ return printed
     self.assertEqual('', field.get_tales('default'))
 
     regexp = '^%s$' % re.escape("Can't find the template field of"
-      " <ProxyField at /%s/portal_skins/erp5_geek/Base_viewGeek/my_title>"
+      " <ProxyField at /%s/portal_skins/erp5_geek/Base_viewGeek/my_proxy_field>"
       % self.portal.getId())
     for func in ( field.render
                 , partial(field.get_value, 'default')
                 , partial(field.get_recursive_tales, 'default')
                 ):
       self.assertRaisesRegexp(BrokenProxyField, regexp, func)
+
+    # we can still view the field in ZMI
+    form.manage_main()
+    field.manage_main()
+    #  and repair it
+    form.manage_addField('my_field', 'Title', 'StringField')
+    field.manage_edit(
+      {
+        'field_form_id': 'Base_viewGeek',
+        'field_field_id': 'my_field',
+      })
+    self.assertEqual(field.getTemplateField(), form.my_field)

product/ERP5Form/ProxyField.py

@@ -171,8 +171,9 @@ class ProxyField(ZMIField):
     Surcharged values from proxied field.
     """
     # Edit template field attributes
-    template_field = self.getRecursiveTemplateField()
+    template_field = self.getTemplateField()
     if template_field is not None:
+      template_field = self.getRecursiveTemplateField()
 
       # Check the surcharged checkboxes
       surcharge_list = []
@@ -581,6 +582,14 @@ class ProxyField(ZMIField):
       # ("form_id and field_id don't define a valid template")
       pass
 
+  security.declareProtected('View', 'title')
+  def title(self):
+    """The title of this field."""
+    try:
+      return super(ProxyField, self).title()
+    except BrokenProxyField:
+      return 'broken'
+
   security.declareProtected('Access contents information', 'has_value')
   def has_value(self, id):
     """

product/ERP5Form/dtml/proxyFieldEdit.dtml

@@ -11,7 +11,7 @@ Surcharge <dtml-var meta_type> properties here.
 <form action="manage_edit" method="POST">
 <table cellspacing="0" cellpadding="2" border="0">
 <dtml-let proxy_field="this()"
-          current_field="proxy_field.getRecursiveTemplateField()">
+          current_field="None if proxy_field.getTemplateField() is None else proxy_field.getRecursiveTemplateField()">
 
   <!-- First, display ProxyField properties -->
   <!-- see: Formulator/dtml/fieldEdit.dtml -->

product/ERP5Form/dtml/proxyFieldTales.dtml

@@ -68,7 +68,7 @@ This tab can therefore not be used.
 
 <!-- XXX Loop until find not a proxy field -->
 <dtml-let proxy_field="this()"
-          current_field="proxy_field.getRecursiveTemplateField()">
+          current_field="None if proxy_field.getTemplateField() is None else proxy_field.getRecursiveTemplateField()">
 
   <dtml-if "current_field is not None">
     <dtml-let form="current_field.tales_form">