Hi Colin.
On behalf of my colleague I will answer your question:
We did not have time (at this moment) to investigate this problem any
further. We've added a raw sql commands to disable foreign key checks
during this migration. We could do it since we are still learning Django
(and it's new migrations) and in the end we will probably remove all
current migrations altogether (just before initial deployment). However we
also think that this might be a bug and we will try to reproduce this
problem with a fresh project. Hopefully sometime this week.
W dniu poniedziałek, 12 stycznia 2015 21:32:39 UTC+1 użytkownik Collin
Anderson napisał:
>
> 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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