Hi,
Did you figure it out? This seems like a bug. Can you reproduce it with a
fresh project?
Thanks,
Collin
On Friday, January 9, 2015 at 8:49:56 AM UTC-5, Maciej Szopiński wrote:
>
> 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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