Wagtail adding ParentalManyToManyField relationship on save()

Question

I'm trying to add a ParentalManyToManyField relationship on save() and when I print it looks good but it doesn't seem to save for some reason.

Example code:

# Models
class BlogProduct(models.Model):
    product_id = models.CharField(max_length=10, blank=False, null=False)

class ProductBlogPage(BlogDetailPage):
    products = ParentalManyToManyField('blog.BlogProduct', blank=True)

    product_details = StreamField(COMMON_BLOCKS + [
        ('product_name', blocks.ProductNameBlock()),
    ],
        null=True, 
        blank=True,
        use_json_field=True,
    )

    def save(self, *args, **kwargs):
        if kwargs.get('update_fields'):
            for product in self.product_details.raw_data:
                blog_product, _ = BlogProduct.objects.get_or_create(product_id='test1')
                    
                    # This is where I'm having trouble to connect product and snippets
                    self.products.add(blog_product)
                    self.save()

            print(self.products.all())
            # This prints out the querySet
            # <QuerySet [<BlogProduct: TestOne>, <BlogProduct: TestTwo>]>

    return super().save(*args, **kwargs)

score 1 · Accepted Answer · answered Nov 27 '22 at 11:11

Your call to return super().save isn't part of your save method, it's getting called during initialisation instead. It just needs indenting:

    def save(self, *args, **kwargs):
        if kwargs.get('update_fields'):
            for product in self.product_details.raw_data:
                blog_product, _ = BlogProduct.objects.get_or_create(product_id='test1')
                
                # This is where I'm having trouble to connect product and snippets
                self.products.add(blog_product)
                self.save()

            print(self.products.all())
            # This prints out the querySet
            # <QuerySet [<BlogProduct: TestOne>, <BlogProduct: TestTwo>]>

        return super().save(*args, **kwargs)

You're also calling save() during each for loop, is this what you intended?

self.products.all() is only looking at the instance in memory, it's not looking at what's saved, which is why your queryset looks ok.

To be honest though, I can't see what you're trying to achieve here. Your product model is just an ID field. You're wanting to be able to add new product ID's directly from the blog page editing interface?

Thank you for explaining richard. I should have been doing a database query rather then self.products.all() to get the list of related items. — squidg, Nov 27 '22 at 12:02
No problem, glad to help :). I'm not sure what you want to achieve here though. Each for loop calls the self.save() method - ie, it will recursively call itself over and over for each product. Most probably not what you're wanting to do as it will call super.save(...) each loop. — Rich - enzedonline, Nov 27 '22 at 14:39

Wagtail adding ParentalManyToManyField relationship on save()

1 Answers1