fields.py 文件源码

def __call__(self, obj):
        """
        Extract a value from `obj` and return the formatted value.
        """
        # Extract value from the object.
        value = self.expr(**{x: getattr(obj, x)
                             for x in dir(obj)
                             if not x.startswith('_')})

        if value is None:
            if self.raise_on_err:
                raise AttributeError(self.path)

        # Get a template, maybe
        template = (self.template if self.template
                    else implicit_templates.get(type(value)))

        if template:
            return render_template_string(template, value=value)
        else:
            return value