def url(value):
    if not url_pattern.match(value):
        raise exceptions.ValidationError("{0} is not a valid URL.".format(value))
    return value
Called to handle each individual (non-relational) field on an object.
dataset/ETHPy150Open transcode-de/durga/durga/validators.py/url--crossover with--dataset/ETHPy150Open AppScale/appscale/AppServer/lib/django-1.5/django/core/serializers/base.py/Serializer.handle_field