text: #!/usr/bin/env python
  # Licensed to Cloudera, Inc. under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  Cloudera, Inc. licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #     http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing, software
  # distributed under the License is distributed on an "AS IS" BASIS,
  # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  # See the License for the specific language governing permissions and
  # limitations under the License.
  
  from django.forms import util
  from django.forms import fields
  from django import forms
  import simplejson
  
  class JsonFormField(fields.CharField):
    """
    Django field for validation JSON data.
  
    Note that this is a form field that defines validation routines,
    not a Model Field.
    
    See http://docs.djangoproject.com/en/1.0/ref/forms/validation/ for details.
  
    The Hampi DataFlowForm class has example usage.
    """
  
    widget = forms.Textarea
  
    default_error_messages = {
      'malformed_json': u'Unable to validate JSON'
      }
    
    def clean(self, value):
      value = super(JsonFormField, self).clean(value)
      try:
        simplejson.loads(value)
      except ValueError, e:
        raise util.ValidationError(e)
      return value
    