在Django模型中，如何根据另一个字段设置Django验证器的值？

from django.db import models
from django.core.exceptions import ValidationError

def validate_name(value):
    if value != 'example':
        raise ValidationError('Name must be "example".')

def validate_age(value):
    if value < 18:
        raise ValidationError('Age must be at least 18.')

class MyModel(models.Model):
    name = models.CharField(max_length=100, validators=[validate_name])
    age = models.IntegerField(validators=[validate_age])