On Wed, Mar 27, 2013 at 11:49 PM, Tim Cook <[email protected]> wrote: > I can't find a similar scenario in the list archives, so ..... > > I had run the initial migration, etc and all seemed fine. > > I modified one model from this: > class CCD(models.Model): > rm_version = models.ForeignKey(RMversion, > related_name='%(class)s_related+') > ... > > to this: > class CCD(models.Model): > prj_name = models.ForeignKey(Project, verbose_name="Project Name") > ... > > The new ForeignKey in CCD, points to this, which already has the > RMversion relation. > > class Project(models.Model): > prj_name = models.CharField("project name", max_length=110, unique=True) > rm_version = models.ForeignKey(RMversion, > related_name='%(class)s_related+') > owner_group = models.CharField(max_length=110) #must be a member > of this group to edit this project > > During the migration, here are the prompts and my responses: >
This should be many migrations, not one migration. 1) Schema migration: Add nullable foreign key to Project to CCD. 2) Data migration: Create Project objects as needed from 'RMversion' links 3) Data migration: Update CCD objects to point at projects 4) Schema migration: Drop RMversion foreign key from CCD 5) Schema migration: Make CCD->Project foreign key not null Splitting it into multiple migration steps stops this from blowing up in your face and preserves your data. Cheers Tom -- You received this message because you are subscribed to the Google Groups "Django users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/django-users?hl=en. For more options, visit https://groups.google.com/groups/opt_out.
