Migration Issue in Django 1.9

[china]

Hi Experts,

I am trying to change the charfield to ForeignKey and I am running my code I am getting the following error if do python manage.py migrate

django.db.utils.DataError: invalid input syntax for integer: "Jeff"

Here is my code

BEFORE

------

reports_to = models.CharField(max_length=128, blank=True, null=True)


in_country_manager = models.CharField(max_length=128, blank=True, null=True)

After
------

reports_to = models.ForeignKey("self", null=True, blank=True, related_name="employee_reports_to")

Could any please help with this issue.

Thanks,

Karthik

[Andréas Kühne]

Hi,

You are changing a CharField into a ForeignKey field with data present. So when the migration tries to run, the reports_to field contains information with a string in it - the database server then tries to set it to a ForeignKey field, which is an integer field per default. This data migration doesn't work and that is what the error is saying.

This can't be migrated automatically without writing your own migrations and even then it won't be easy,.

If you don't care about the current value of the reports_to field, you can do this in 2 migrations - one to remove the field and another to add the foreign key field. Or you can just add a drop column for the old reports to field in the same migration.

If you do care, I would probably do something like this:

1. Rename the current field.

2. Add the new foreign key field

3. Migrate the data via a custom migration.

Regards,

Andréas

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[china]

Hi Andreas,

Thank you for you quick response

Is it possible if remove my migration files and rollback my migration to three  migrations back..?

Thanks,

Karthik

[Andréas Kühne]

Hi,

Yes you can roll back your migrations (I think).... But you weren't able to get by that migration and it's only that migration that you need to handle. The other migrations haven't yet been migrated and you can just delete them from your disk in that case?

Regards,

Andréas

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[china]

Hi Andreas,

I have fixed the issue. Here is how i achieved....

1. I removed the field reports_to and added a field report_new(with foreign key)

        -  reports_to = models.CharField(max_length=128, blank=True, null=True)---(Removed this line)
        + report_new = models.ForeignKey("self", null=True, blank=True, related_name="employee_reports_to")

        2. Altered the field name reports_new to reports_to

         changed this

         

report_new = models.ForeignKey("self", null=True, blank=True, related_name="employee_reports_to")

 

         to 

report_new = models.ForeignKey("self", null=True, blank=True, related_name="employee_reports_to")

Thank you very much for your response it helped me a lot.

Thanks,

Karthik