Alter model to add "through" relationship to order a ManytoMany field - Django 1.7 migration modification -

Alter model to add "through" relationship to order a ManytoMany field - Django 1.7 migration modification -

i trying add together order manytomany field created while ago. want order pictures in collections of pictures. running on django 1.7, no more south migrations (i trying follow tutorial: http://mounirmesselmeni.github.io/2013/07/28/migrate-django-manytomany-field-to-manytomany-through-with-south/)

here's "through" relationship have:

class collectionpictures(models.model): image = models.foreignkey( picture, verbose_name=u'picture', help_text=u'picture included in collection.', ) collection = models.foreignkey( collection, verbose_name=u'collection', help_text=u'picture included in collection', ) order = models.integerfield( verbose_name=u'order', help_text=u'what order display image within collection.', max_length=255 ) class meta: verbose_name = u"collection picture" verbose_name_plural = u"collection pictures" ordering = ['order', ] def __unicode__(self): homecoming self.picture.name + " displayed in " + self.collection.name + ( " in position %d" % self.order) class collection(models.model): pictures = models.manytomanyfield(picture, through='collectionpictures', null=true) [... bunch of irrelevant stuff after]

so should work if didn't have migrate old info (the difference in model didn't have through='collectionpictures'

here's migration :

class migration(migrations.migration): dependencies = [ ('artist', '0002_auto_20141013_1451'), ('business', '0001_initial'), ] operations = [ migrations.createmodel( name='collectionpictures', fields=[ ('id', models.autofield(verbose_name='id', serialize=false, auto_created=true, primary_key=true)), ('order', models.integerfield(help_text='what order display image within collection.', max_length=255, verbose_name='order')), ('collection', models.foreignkey(verbose_name='collection', to='business.collection', help_text='picture included in collection')), ('picture', models.foreignkey(verbose_name='picture', to='artist.picture', help_text='picture included in collection.')), ], options={ 'ordering': ['order'], 'verbose_name': 'collection picture', 'verbose_name_plural': 'collection pictures', }, bases=(models.model,), ), migrations.alterfield( model_name='collection', name='pictures', field=models.manytomanyfield(to=b'artist.picture', null=true, through='business.collectionpictures'), ), ]

this throws error when migrating:

valueerror: cannot alter field business.collection.pictures business.collection.pictures - not compatible types (you cannot alter or m2m fields, or add together or remove through= on m2m fields)

has tried kind of manipulation new 1.7 migrations?

thanks !

the safest approach create new field , re-create info over.

leave pictures lone , add together pictures2 through field. run makemigrations.

edit generated migration file , add together runpython command re-create info old table new table. perhaps can programmatically take value new order column well.

delete old pictures field. run makemgirations.

rename pictures2 pictures. run makemigrations.

this approach should leave in state want info intact.

if copying on info big problem seek else, adding order column in sql, using db_table alternative on collectionpictures create point existing table, , wiping out migrations , redoing --fake. seems riskier approach above.

django migration manytomanyfield django-1.7 django-migrations