How does django haystack know which field of model is found?

I used django to build a website, in which there are multiple rich text field, in a model. I use django-haystack to do a site-wide search, but only the entire model instance is returned. How do I know which field has been found in this model instance?

the following is my code

-sharpmodels.py
class Version(models.Model):
    name=models.CharField("",max_length=25)
    user = models.ForeignKey(User,on_delete=models.CASCADE,verbose_name="")
    update_description = RichTextUploadingField("")
    description=RichTextUploadingField("")
    publish_date = models.DateTimeField("",auto_now_add=True)
    reports=RichTextUploadingField("")
    scripts=RichTextUploadingField("")

-sharpsearch_indexs.py
class VersionIndex(indexes.SearchIndex, indexes.Indexable):
    text = indexes.CharField(document=True, use_template=True)

    def get_model(self):
        return Version

    def index_queryset(self, using=None):
        return self.get_model().objects.all()

-sharpversion_text.txt
{{ object.name }}
{{ object.update_description }}
{{ object.description }}
{{ object.reports }}
{{ object.scripts }}