CODEWITHSUNDEEP
pythonmysqldjango
jalanga
jalanga

Reputation: 1576

Django query get day from DateTimeField

I have some orders saved in database, I want to retrieve just the day from order, so I did this:

Order.objects.all().extra(select={'day':'day(date_added)'}).values('day').order_by('day')

But I get this error: django.db.utils.OperationalError: (1052, "Column 'date_added' in field list is ambiguous"), and my Order model has the field date_added.

My model:

class Order(models.Model):
    user = models.ForeignKey(User, related_name="orders")
    date_added = models.DateTimeField(default=timezone.now)

Any solutions?

Upvotes: 2

Views: 1077

Answers (1)

bozdoz
bozdoz

Reputation: 12890

That error is likely occurring because there is another field named date_added in that SQL: for example, a related table could have the same field.

You could try prepending the table name to the field:

.extra(select={'day':'day(app_order.date_added)'})

Assuming the table name is app_order.

See more on Django's extra method: https://docs.djangoproject.com/en/1.9/ref/models/querysets/#extra

In particular, look at the section on getting the Blog object count:

SELECT COUNT(*) FROM blog_entry WHERE blog_entry.blog_id = blog_blog.id

Note the use of the tablename blog_blog.

For more reference:

The value in field list is ambiguous error: Column 'user_id' in field list is ambiguous

Upvotes: 2

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