django taggit self.tags.add() in not working in django

[naveedur]

I am using djagno-taggit. I want to add other fields data automatically when I save the data table.
models.py:

class resource(models.Model):
    title=models.CharField(max_length=100)
    size=models.CharField( max_length=20, default="")
    desc=models.TextField(default="")
    file=models.FileField(default="", blank=True)
    url= models.URLField(max_length=200, blank=True)
    varient=models.CharField(max_length=100, default="")
    Brand = models.ForeignKey(brand,on_delete=models.CASCADE, default="")
    Model = models.ForeignKey(model,on_delete=models.CASCADE, default="")
    Categories = models.ForeignKey(category,on_delete=models.CASCADE, default="")
    update_at=models.DateField(auto_now=True)
    slug=models.SlugField(default="", unique=True, blank=True)
    tags_char=models.TextField( blank=True)
    Tags = TaggableManager(blank=True) 

    def save(self, *args, **kwargs):
      getlast=resource.objects.all().last()
      getid=getlast.id
      print(getid)
      newid=int(getid)+1
      if not self.pk:
          self.pk=newid
      self.tags_char= self.desc+","+self.size
      ans=[self.title ,self.desc,self.size]
      self.Tags.add(*ans)
      print(self.Tags.all())
      for tag in self.tags_char.split(','):
              print(tag)
      super(resource, self).save(*args, **kwargs)

Here first I get pk for current data and try to save list that has the same data fields in the Tags fields. It works well when I Print Tagsafter adding and get the below result in my terminal when I

print(self.Tags.all())
result in the terminal is:
<QuerySet [<Tag: tagSize>, <Tag: tagTitle>, <Tag: tagDescription>]>
But when I open it in the admin models data table then I got Tags fields empty!!
Any solution??

[rtpg]

@naveedur I'm not 100% sure here but your code might be having an issue because you call super().save(*args, **kwargs) after editing the tags (so the pk might get changed up).

Could you try calling super().save(*args, **kwargs), then saving your tags?