Question

I have models like this:

class Vendor(models.Model):
    title = models.CharField()

class Product(models.Model):
    ...
    vendor = models.ForeignKey(Vendor, null=True, blank=True)
    stock = models.ManyToManyField(Supplier, through='Stock')

class Stock(models.Model):
    in_stock = models.BooleanField(default=True)
    supplier = models.ForeignKey('catalog.Supplier', related_name='supplier_stock')
    product = models.ForeignKey('catalog.Product', related_name='product_stock')
    priority = models.IntegerField(default=0)

I designed models like this, because one Product can be supplied by different suppliers, and I need to know, what supplier exactly has this Product in stock.

So, in my view I want to get all results in values, to reduce number of queries and some specific logic. Also it duplicates me Product row with different Stock, by in python I group them up.

In my view I use:

Product.objects.all().values(
    'id', 'title', 'vendor_code', 'vendor__title', 'price', 
    'product_stock__in_stock', 'stock__title', 'stock__id', 'stock__priority')

Because of INNER JOIN and null=True for Vendor related model, it returns me not all records for Product model. It just returns values where Vendor reference is set.

If I use ‘vendor’ instead of ‘vendor__title’ it returns me more results, than previous one, because in vendor field I can get {...'vendor': *id goes here*...} or {...'vendor': None...}, but I need the vendor__title value there. So any suggestions, how to achieve this?

Thanks in advance

Answer 1

Changed from vendor__title to product_stock__product__vendor__title helped me to fix my problem.