Hi everyone,
I've encountered an issue when working with django and I can't seem to find
a way out of this..
I am using django 1.7.2 and a MySQL database.
I have a model that was using a One-to-One relationship with two other
models. At first I thought, the One-to-One relationship will be enough, but
as things changed in the project I had to change the relationship to
Many-to-One.
I changed only two lines in my code, in my model I had:
product = models.OneToOneField(Product)
category = models.OneToOneField(Category)
and changed it to:
product = models.ForeignKey(Product)
category = models.ForeignKey(Category)
I created the db migrations using ./manage.py makemigrations, but when I
run the migration with 'migrate' it keeps throwing this error.
django.db.utils.OperationalError: (1553, "Cannot drop index 'product_id':
needed in a foreign key constraint")
I tried to check what sql operations are executed in this case and it seems
that django tries to run
ALTER TABLE 'xxx' DROP INDEX 'yyy' and
ALTER TABLE `xxx` DROP FOREIGN KEY `xxx_yyy_id_{some_hash}_fk_yyy_id`;
I am not sure if this is the right order for these operations, when running
it manually on the database in the reverse order (first the DROP FOREIGN
KEY then DROP INDEX) it works correctly.
Have you encountered this issue before? Have you got any suggestions on how
to resolve this situation?
I would like to avoid any manual SQL changes outside of django migrations.
Thanks in advance.
Best regards,
Maciej Szopiński
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