Is this MySQL query equivalent to this Django query

Simon Published at Java

simon

Is this MySQL Query

SELECT * from books WHERE ISBN = (SELECT isbn_id FROM userWishlist WHERE userid_id = request.user.id)

equivalent to this Django query?

q = userWishlist.objects.filter(userid_id = request.user.id).values('isbn_id')

return books.objects.filter(ISBN = q)

edit: Here are the models for userWishList and book

class books (models.Model):
    ISBN = models.IntegerField(primary_key=True)
    bookName = models.CharField(max_length=255)
    bookVersion = models.CharField(max_length=255)
    bookAuthor = models.CharField(max_length=255)
    bookPublisher = models.CharField(max_length=255, default= 'NULL')
class wishlist (models.Model):
    userid = models.ForeignKey(User, on_delete= models.CASCADE)
    ISBN = models.ForeignKey(books, on_delete = models.CASCADE)

Willem Van Onsem

equivalent to this Django query?

No. Django expects a single value for equivalences, but the q object is a QuerySet of values.

Furthermore it is not necessary to use this. You can filter with:

books.objects.filter(wishlist__userid=request.user)

This will thus list all books for which a wishlistexists which has asuseridtherequest.user`.

Note: Models in Django are written in PerlCase, not snake_case, so you might want to rename the model from ~~wishlist~~ to Wishlist.

Note: normally a Django model is given a singular name, so Book instead of ~~books~~.

Note: It is normally better to make use of the settings.AUTH_USER_MODEL [Django-doc] to refer to the user model, than to use the User model [Django-doc] directly. For more information you can see the referencing the User model section of the documentation.

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