text: """Database models."""
  from __future__ import absolute_import, unicode_literals
  
  from django.db import models
  from django.utils.translation import ugettext_lazy as _
  
  from celery import states
  from celery.five import python_2_unicode_compatible
  
  from . import managers
  
  ALL_STATES = sorted(states.ALL_STATES)
  TASK_STATE_CHOICES = sorted(zip(ALL_STATES, ALL_STATES))
  
  
  @python_2_unicode_compatible
  class TaskResult(models.Model):
      """Task result/status."""
  
      task_id = models.CharField(
          _('task id'),
          max_length=255, unique=True,
      )
      status = models.CharField(
          _('state'),
          max_length=50, default=states.PENDING,
          choices=TASK_STATE_CHOICES,
      )
      content_type = models.CharField(
          _('content type'), max_length=128,
      )
      content_encoding = models.CharField(
          _('content encoding'), max_length=64,
      )
      result = models.TextField(null=True, default=None, editable=False)
      date_done = models.DateTimeField(_('done at'), auto_now=True)
      traceback = models.TextField(_('traceback'), blank=True, null=True)
      hidden = models.BooleanField(editable=False, default=False, db_index=True)
      meta = models.TextField(null=True, default=None, editable=False)
  
      objects = managers.TaskResultManager()
  
      class Meta:
          """Table information."""
  
          verbose_name = _('task result')
          verbose_name_plural = _('task results')
  
      def as_dict(self):
          return {
              'task_id': self.task_id,
              'status': self.status,
              'result': self.result,
              'date_done': self.date_done,
              'traceback': self.traceback,
              'meta': self.meta,
          }
  
      def __str__(self):
          return '<Task: {0.task_id} ({0.status})>'.format(self)
  