def retry_failed_fields(self):
        "Tries to re-evaluate the _failed_fields for each model."
        for modelkey, model in self.models.items():
            app, modelname = modelkey.split(".", 1)
            if hasattr(model, "_failed_fields"):
                for fname, (code, extra_imports) in model._failed_fields.items():
                    try:
                        field = self.eval_in_context(code, app, extra_imports)
                    except (NameError, AttributeError, AssertionError, __HOLE__) as e:
                        # It's failed again. Complain.
                        raise ValueError("Cannot successfully create field '%s' for model '%s': %s." % (
                            fname, modelname, e
                        ))
                    else:
                        # Startup that field.
                        model.add_to_class(fname, field)
dataset/ETHPy150Open cloudera/hue/desktop/core/ext-py/South-1.0.2/south/orm.py/_FakeORM.retry_failed_fields