How to implement `others` for a Django Model Choices-CharField?

I have a Django model that has several CharFields. A lot of these represent information of the type

1. Item Type 1
2. Item Type 2
3. Others

The usual way of defining choices for a CharField is

            models.CharField(            max_length=255,            choices=ChoiceList.choices, # Defining Choices        )

As you would have guessed, this fails to meet my requirements since I cannot pass it anything(Others) apart from the pre-defined choices.

I cannot discard the choices parameter since I need the model to have the choices information for each field. This will be used to fetch all legal options for a particular field.

I tried using a custom validator function

def validate_choice(value, choices):    if value == "Others:":        print(value, choices)    valid_choices = [choice[0] for choice in choices]    if not value.startswith("Others:") and value not in valid_choices:        raise ValidationError(f"{value} is not a valid choice")

(For simplicity, I defined my logic as

1. Either the value is in the Choice List
2. Or it starts with Others: (To indicate that it is a deliberate Other value)

And subsequently, I modified the CharField as follows, to use the new Validator Function

        models.CharField(            max_length=255,            choices=IPCSections.choices,            validators=[partial(validate_choice, choices=ChoiceList.choices)],        )

I then noticed that The Choice validation (By Django) happens before the custom validator is called. Which, again leads the the same issue

Others:% is not a valid choice

Looking up in the Django Documentation, I found methods like

model.clean()model.clean_all() etc.

I tried overriding these methods, but did not end up with anything useful and the documentation does not cover exactly in what order and when are they called.