Python Django のモデルをテンプレートに表示できない

Djangoのテンプレートにモデルを表示させたいです。

product_list.htmlに

{% for product in products %}
{{ product.name }}
{% endfor %}
だと表示されるのですが、tagsに変更すると
shop.PostTag.None と表示されてしまうので
解決方法教えていただきたいです。

models.py
1from django.db import models
2from django.urls import reverse
3from django.shortcuts import render
4
5
6class PostTag(models.Model):
7    name = models.CharField(max_length=200)
8    
9    def __str__(self):
10        return self.name
11
12def image_path(instance, filename):
13    ext = filename.split('.')[-1]
14    new_name = instance.name
15    return f'producthover/{new_name}.{ext}'
16
17class Product(models.Model):
18    name = models.CharField(verbose_name='商品名', max_length=250, unique=True)
19    slug = models.SlugField(verbose_name='URLに表示される名前', max_length=250, unique=True)
20    description = models.TextField(verbose_name='説明', blank=True)
21    price = models.IntegerField()
22    image = models.ImageField(upload_to='product', blank=True)
23    hover_image = models.ImageField(verbose_name='ポップアップの画像', upload_to=image_path, blank=True, )
24    stock = models.IntegerField()
25    available = models.BooleanField(default=True)
26    created = models.DateTimeField(auto_now_add=True)
27    updated = models.DateTimeField(auto_now=True)
28
29    tags = models.ManyToManyField(PostTag)
30
31    objects = models.Manager()
32
33    valid_objects = ValidManager()
34
35    class Meta:
36        ordering = ('name',)
37        verbose_name = 'product'
38        verbose_name_plural = 'products'
39    def __str__(self):
40        return '{}'.format(self.name)
41
42    def get_url(self):
43        return reverse('shop:product_detail', args=[self.slug])
44
45    def index(request):
46        image_request = request.user.set_image_path
47        return render(request, 'shop/base.html', {'image_request': image_request}) 
48

views.py
1from django.shortcuts import render
2
3from shop.models import Product
4
5from django.core.paginator import Paginator, EmptyPage, InvalidPage
6
7
8def all_products(request):
9    products_list = Product.valid_objects.all()
10
11    paginator = Paginator(products_list, per_page=16)
12    try:
13        page = int(request.GET.get('page', '1'))
14    except:
15        page = 1
16
17    try:
18        products = paginator.page(page)
19    except (EmptyPage, InvalidPage):
20        products = paginator.page(paginator.num_pages)
21        
22    return render(request, 'shop/product_list.html', {'products': products})
23