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Python Django Basics Django Templates Step by Step

Posted by Marc Busby
Marc Busby
35,550 Points

Make Migrations on the newer version of Django

Just in case anyone else is following along on their local machine and is using a newer version of Django, you will probably get an error when you try and run the migrations suggesting that the Foreign Key requires an additional argument.

Changing the line to: 

course = models.ForeignKey(Course, on_delete=models.CASCADE)

Should fix the issue.

Steve Dempster
Steve Dempster
5,868 Points

Worked! Thanks for sharing, Marc!

Xayaseth Boudsady
Xayaseth Boudsady
21,951 Points

Thanks Marc Busby I thought was doing something wrong. This should be included in the Teacher's note.

Taehwa Kang
Taehwa Kang
8,097 Points

Thanks a lot! you saved me!

darcyprice
darcyprice
4,442 Points

Thanks Marc! :)

Anna Muravyeva
Anna Muravyeva
12,162 Points

This seems to work, too. Does anyone know the difference?

course = models.ForeignKey(Course, on_delete=models.DO_NOTHING)
Jonatan Witoszek
Jonatan Witoszek
15,384 Points

@Anna Muravyeva the difference is that if you set models.CASCADE, Django will delete every Step entry related to specified Course if that course gets deleted. In contrast models.SET_NULL will... well, sets the course field to null.

There's more in the Django documentation

Rohan Tinna
Rohan Tinna
3,415 Points

Thanks ;)

Ben Hendricks
.a{fill-rule:evenodd;}techdegree
Ben Hendricks
Python Web Development Techdegree Student 15,217 Points

much appreciated!