text: import uuid
  
  from django.contrib.auth.models import User
  from django.db import models
  
  from projects.models import Project
  from .managers import ExampleManager, ExampleStateManager
  
  
  class Example(models.Model):
      objects = ExampleManager()
  
      uuid = models.UUIDField(default=uuid.uuid4, editable=False, db_index=True, unique=True)
      meta = models.JSONField(default=dict)
      filename = models.FileField(default=".", max_length=1024)
      project = models.ForeignKey(to=Project, on_delete=models.CASCADE, related_name="examples")
      annotations_approved_by = models.ForeignKey(to=User, on_delete=models.SET_NULL, null=True, blank=True)
      text = models.TextField(null=True, blank=True)
      created_at = models.DateTimeField(auto_now_add=True, db_index=True)
      updated_at = models.DateTimeField(auto_now=True)
  
      @property
      def comment_count(self):
          return Comment.objects.filter(example=self.id).count()
  
      @property
      def data(self):
          if self.project.is_text_project:
              return self.text
          else:
              return str(self.filename)
  
      class Meta:
          ordering = ["created_at"]
  
  
  class ExampleState(models.Model):
      objects = ExampleStateManager()
      example = models.ForeignKey(to=Example, on_delete=models.CASCADE, related_name="states")
      confirmed_by = models.ForeignKey(to=User, on_delete=models.CASCADE)
      confirmed_at = models.DateTimeField(auto_now=True)
  
      class Meta:
          unique_together = (("example", "confirmed_by"),)
  
  
  class Comment(models.Model):
      text = models.TextField()
      example = models.ForeignKey(to=Example, on_delete=models.CASCADE, related_name="comments")
      user = models.ForeignKey(to=User, on_delete=models.CASCADE, null=True)
      created_at = models.DateTimeField(auto_now_add=True, db_index=True)
      updated_at = models.DateTimeField(auto_now=True)
  
      @property
      def username(self):
          return self.user.username
  
      class Meta:
          ordering = ["created_at"]
  