Plone- In a dexterity.EditForm why is attempting to disable a widget causing a ConstraintNotSatisfied error? -

i'm trying disable widget in dexterity.editform, i'm getting error .

here part of interface class particular widget want disable

class irestaurant(iplace):      restaurant_code = schema.textline(title=_(u""),                                       required=false,                         ) 

iplace form.schema irestaurant inherits from. (from plone.directives)

here code dexterity.editform class:

class edit(dexterity.editform):     grok.context(irestaurant)      def updatewidgets(self):         super(edit, self).updatewidgets()         self.widgets['restaurant_code'].disabled = true 

when go edit form, error:

constraintnotsatisfied: true 

why error occurring , how can fix this?

also, version of plone using plone 4.3.5.

edit: when tried printing type of object self.widgets['restaurant_code'].disabled was, said nonetype object.

you might have better luck using mode property.

try this:

from z3c.form.interfaces import hidden_mode  def updatewidgets(self):     super(edit, self).updatewidgets()     self.widgets['restaurant_code'].mode = hidden_mode