Django How to get the value from many to many relationship - django

Question

I have a product update form where I want to update the sizes of a product, with a many-to-many column relation.
I am able to get the saved values but I can't get item ID or size.
{{item.id}} shows empty value.
{% for item in form.size.value %}
<span>
<input type="checkbox" name="size" id="{{ item.id }}" value="{{ item.id }}">
<label for="{{ item.id }}">{{ item }}</label>
</span>
{% endfor %}
SIZE MODEL
class Size(models.Model):
identifier = models.UUIDField(default=uuid.uuid4, editable=False, unique=True)
size = models.CharField(max_length=200, unique=True, null=False, blank=False)
active = models.BooleanField(default=True)
date_created = models.TimeField(verbose_name='Date Created', auto_now_add=True)
date_updated = models.DateTimeField(verbose_name='Last Updated', auto_now=True)
PRODUCT MODEL
class Product(models.Model):
identifier = models.UUIDField(default=uuid.uuid4, editable=False, unique=True)
name = models.CharField(max_length=200, null=False, blank=False)
slug = models.SlugField(max_length=30, unique=True)
showcased = models.BooleanField(default=False)
recommended = models.BooleanField(default=False)
active = models.BooleanField(default=True)
price = models.DecimalField(max_digits = 5, decimal_places = 2, null=True, blank=True)
pagetitle = models.CharField(max_length=200, null=True, blank=True)
shortDescription = models.CharField(max_length=200, null=True, blank=True)
longDescription = HTMLField(null=True, blank=True)
specifications = models.TextField(null=True, blank=True)
features = models.TextField(null=True, blank=True)
care = models.TextField(null=True, blank=True)
category = models.ForeignKey(Category, on_delete=models.PROTECT)
subCategory = models.ForeignKey(SubCategory, null=True, blank=True, on_delete=models.PROTECT)
image = models.ManyToManyField(Image, blank=True)
size = models.ManyToManyField(Size, blank=True)
tag = models.ManyToManyField(Tag, blank=True)
date_created = models.TimeField(verbose_name='Date Created', auto_now_add=True)
date_updated = models.DateTimeField(verbose_name='Last Updated', auto_now=True)
I have tried different ways but not had success in getting the name or id
def updateProduct(request, pk):
categories = Category.objects.all()
sizes = Size.objects.all()
tags = Tag.objects.all()
product = Product.objects.get(id=pk)
subCategories = SubCategory.objects.filter(category=product.category.id)
images = product.image.all()
if request.method == 'POST':
form = ProductForm(request.POST, instance=product)
if form.is_valid():
form.save()
return redirect('product-panel')
form = ProductForm(instance=product)
return render(request, 'public/views/backend/product-update.html', {'categories':categories,'subCategories':subCategories, 'sizes':sizes, 'tags':tags, 'form':form, 'images':images})