old_contents: from django.db.models.fields import FieldDoesNotExist
  from haystack import indexes
  
  from .models import Article
  
  
  class TempArticleIndex(indexes.SearchIndex):
      title = indexes.CharField(model_attr='title')
      name = indexes.CharField(model_attr='title')
      text = indexes.CharField(document=True, use_template=True)
  
      def get_model(self):
          return Article
  
      def index_queryset(self, **kwargs):
          return self.get_model().objects.active()
  
      def get_updated_field(self, **kwargs):
          try:
              self.get_model()._meta.get_field('modification_date')
          except FieldDoesNotExist:
              return None
          else:
              return 'modification_date'
  
  
  try:
      # In haystack < 2.0 we need to explicitly register indexes
      from haystack import site
  except ImportError:
      # In haystack >= 2.0 Indexes subclass indexes.Indexable
      class ArticleIndex(TempArticleIndex, indexes.Indexable):
          pass
  else:
      class ArticleIndex(TempArticleIndex):
          def get_queryset(self):
              return self.index_queryset()
  
      site.register(Article, ArticleIndex)
  
new_contents: from django.db.models.fields import FieldDoesNotExist
  from haystack import indexes
  
  from .models import Article
  
  
  class TempArticleIndex(indexes.SearchIndex):
      title = indexes.CharField(model_attr='title')
      name = indexes.CharField(model_attr='title')
      text = indexes.CharField(document=True, use_template=True)
  
      def get_model(self):
          return Article
  
      def index_queryset(self, using=None):
          return self.get_model().objects.active()
  
      def get_updated_field(self, **kwargs):
          try:
              self.get_model()._meta.get_field('modification_date')
          except FieldDoesNotExist:
              return None
          else:
              return 'modification_date'
  
  
  try:
      # In haystack < 2.0 we need to explicitly register indexes
      from haystack import site
  except ImportError:
      # In haystack >= 2.0 Indexes subclass indexes.Indexable
      class ArticleIndex(TempArticleIndex, indexes.Indexable):
          pass
  else:
      class ArticleIndex(TempArticleIndex):
          def get_queryset(self):
              return self.index_queryset()
  
      site.register(Article, ArticleIndex)
  
subject: Use using=None explicitly.