def get_body_validator(models):
    """Returns a validator for the request body, based on a
    :class:`jsonschema.validators.Draft4Validator`, with extra validations
    added for swaggers extensions to jsonschema.

    :param models: a mapping of reference to models
    :returns: a :class:`jsonschema.validators.Validator` which can validate
        the request body.
    """
    return validators.extend(
        Draft4Validator,
        {
            'paramType': ignore,
            'name': ignore,
            'type': build_swagger_type_validator(models),
            'required': required_validator,
        }
    )