text: from django.db import models
  from django.utils import timezone
  
  from .Auditable import Auditable
  
  
  class CredentialSet(Auditable):
      reindex_related = ["topic"]
  
      credential_type = models.ForeignKey(
          "CredentialType", related_name="credential_sets", on_delete=models.CASCADE
      )
      cardinality_hash = models.TextField(db_index=True, null=True)
      latest_credential = models.ForeignKey(
          "Credential", related_name="+", null=True, on_delete=models.SET_NULL
      )
      topic = models.ForeignKey(
          "Topic", related_name="credential_sets", on_delete=models.CASCADE
      )
  
      first_effective_date = models.DateTimeField(null=True)
      last_effective_date = models.DateTimeField(null=True)
  
      class Meta:
          db_table = "credential_set"
          unique_together = (("topic", "credential_type", "cardinality_hash"),)
          ordering = ("id",)
  