Re: left join without where condition

You are telling something which I know already. Please observe my question keenly I need reverse of what you told. I. e. 

Photo modal has Product as ForeignKey

class Photo:

           file=models.FileField() 

           product=models.ForeignKey() 

          

On 26 Apr 2019 19:16, "Matthew Pava" <Matthew.Pava@iss.com> wrote:

Use select_related or just reference it in the template as an attribute.

https://docs.djangoproject.com/en/2.1/ref/models/querysets/#select-related

 

Product.objects.select_related('photo')

 

{% if product.photo %}

            …

{% endif %}

 

From: django-users@googlegroups.com [mailto:django-users@googlegroups.com] On Behalf Of pythonwebdjango@gmail.com
Sent: Friday, April 26, 2019 8:03 AM
To: Django users
Subject: left join without where condition

 

What exactly I need?

  I have 2 models Product and Photo(having ForeignKey relationship with Product). Now suppose I inserted 3 products in Product table. For the 3rd product I not inserted any photo in Photo table. I want to fetch all the Products along with Photos but for the 3rd product photo should come as null(or None) because I not inserted. why I am doing like this because for the product for which no photos are uploaded I can check in the template that if null or None is coming as a photo then show a default image referring it from the static folder. I know we can achieve it using left join but how to achieve it in Django style?

 

What I have tried?

q=Product.objects.all().filter(photo__isnull=True)

print(q.query)

SELECT "app_product"."id", "app_product"."name"  FROM "app_product" LEFT OUTER JOIN "app_photo" ON

("app_product"."id" = "app_photo"."product_id") WHERE "app_photo"."id" IS NOT NULL

 

If in the above query I remove the where clause my problem will be resolved?

So how to do that in a django way?

 

 

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