Django-Taggit get random tags skipping those not assigned to a Post

Question

I want to give my users suggestions of random tags when they click on the search bar. So far my code returns what I want BUT it is also returning tags that are not assigned to any Post IE: when I delete a post or delete its tags those tags are still showing up in the suggestions.

# Get the suggestions (In View)
suggestions = Tag.objects.all().distinct().order_by('?')[:5]

# Model
class Post(models.Model):
title = models.CharField(max_length=256)
disclaimer = models.CharField(max_length=256, blank=True)
BLOGS = 'blogs'
APPLICATIONS = 'applications'
GAMES = 'games'
WEBSITES = 'websites'
GALLERY = 'gallery'
PRIMARY_CHOICES = (
    (BLOGS, 'Blogs'),
    (APPLICATIONS, 'Applications'),
    (GAMES, 'Games'),
    (WEBSITES, 'Websites'),
)
content_type = models.CharField(max_length=256, choices=PRIMARY_CHOICES, default=BLOGS)
screenshot = models.CharField(max_length=256, blank=True)
tags = TaggableManager()
body = RichTextField()
date_posted = models.DateTimeField(default=datetime.now)
date_edited = models.DateTimeField(blank=True, null=True)
visible = models.BooleanField(default=True)
nsfw = models.BooleanField()
allow_comments = models.BooleanField(default=True)
files = models.ManyToManyField(File, blank=True)

def __str__(self):
    if (self.visible == False):
        return '(Hidden) ' + self.title + ' in ' + self.content_type
    return self.title + ' in ' + self.content_type

Answer 1

If you want only the tags assigned to posts you have to query the posts for their tags and pick five of these:

allposts = Post.objects.all()
five_tags = list(set([tag.slug for post in allposts for tag in post.tags.all()]))[:5]

(use set() to remove duplicates)

EDIT

If you want to shuffle all tags before pick five you can do something like:

import random

allposts = Post.objects.all()
all_tags_list = list(set([tag.slug for post in allposts for tag in post.tags.all()]))
random.shuffle(all_tags_list)
five_tags = all_tags_list[:5]