objects.py 文件源码

def _compute_fields_for_operation(self, fields, to_compute):
        row = OpRow(self)
        for name, tup in iteritems(fields):
            field, value = tup
            if isinstance(
                value, (
                    types.LambdaType, types.FunctionType, types.MethodType,
                    types.BuiltinFunctionType, types.BuiltinMethodType
                )
            ):
                value = value()
            row.set_value(name, value, field)
        for name, field in to_compute:
            try:
                row.set_value(name, field.compute(row), field)
            except (KeyError, AttributeError):
                # error silently unless field is required!
                if field.required and name not in fields:
                    raise RuntimeError(
                        'unable to compute required field: %s' % name)
        return row