Define an attribute of a dataclass with a reserved word "class" and serialize it

Question

Ok I'm trying to define a dataclass to enqueue a job in redis for a sidekiq worker, the specification of the sidekiq payload requires some attributes something with this format:

{
  "class": "SomeWorker",
  "queue": "default"
  "jid": "b4a577edbccf1d805744efa9", // 12-byte random number as 24    char hex string
  "args": [......],
  "created_at": 1234567890,
  "enqueued_at": 1234567890
 }

So I define a dataclass in my python code:

@dataclass
class PusherNotificationJob:
   args: Any = None
   queue: str = "default"
   jid: str = secrets.token_hex(12)
   retry: bool = True
   created_at: datetime.datetime = time.time()
   enqueued_at: datetime.datetime = time.time()

   def asdict(self):
       return {** self.__dict__, "class": "SomeWorker"}

My problem is that I can't define "class" as an attribute of PusherNotificationJob because it's a reserved word. So I need to define the asdict method to serialize as a dict and add the "class" attribute I added here.

There is a better way to do this?

Checker

May you can try to use a lib to do that. Take a look at serpy. twilio.com/blog/2017/08/… – Hades

Answer 1

A few things to pay attention before the answer: created_at and enqueued_at will have the same value for as long as your code is running... if you want the time to be when the instance was created, use:

created_at: datetime.datetime = field(default_factory=time.time)

moving on:

You can override __iter__ to use dict(instance). It would be something like below if you have an attribute named class_: str = 'SomeWorker'

def __iter__(self):
    for key in self.__dict__:
        if key == 'class_':
            key = 'class'
        yield key, self.__dict__

If you need __iter__ to behave normally, you use the following:

def convert_keys(self):
    for key in self.__dict__:
        value = self.__dict__[key]
        if key == 'class_':
            key = 'class'
        yield key, value 

def asdict(self):
    return {key: value for key, value in self.convert_keys()}

Flesher