Hey Kyle, that sounds about right. It's a variation of the "Migration Recipe" I came up with a while ago: https://markusholtermann.eu/2016/04/django-migrations-recipe-2/ . My question would be if you really need the field of the new type to have the exact same name as the old one. If you can live or deal with the new type using a different name it's much easier as you don't need to migrate data twice.
/Markus On Wed, Mar 13, 2019, at 4:41 AM, 'Kyle Mulka' via Django users wrote: > Hi there, > > Wondering if there's any tool out there to make a zero downtime field > type change easier. I want to change a django model field from one type > to another, and the format of the field in the database is slightly > different. > > I've come up with a process I think will work, but it will be rather > tedious if done manually. Wondering if there's a more automated > approach or other tools out there already. I'd like to come up with a > general solution for use in the future, but right now trying to tackle > converting UUIDField from django-extensions to the built in django > version. > https://github.com/django-extensions/django-extensions/issues/647 > > I was thinking about maybe using a custom field that supports both > types, but not exactly sure how to write a custom field that would do > that. > > If it helps, the manual process I'm thinking about kind of goes as follows: > > # existing model: > class Model: > field = OldField() > > # add field_old with OldField type > # when updating or adding rows start writing to both fields > # copy data from field to field_old > class Model: > field = OldField() > field_old = OldField() > > # stop using field, only use field_old > # remove field > class Model: > field_old = OldField() > > # create field with new type > # when updating or adding rows start writing to both fields in their > respective formats > # copy data from field_old in old format to field in new format > class Model: > field = NewField() > field_old = OldField() > > # stop using field_old > # remove field_old > class Model: > field = NewField() > > Thanks for your help! > > -- > Kyle Mulka > http://www.kylemulka.com > > -- > 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 django-users+unsubscr...@googlegroups.com. > To post to this group, send email to django-users@googlegroups.com. > Visit this group at https://groups.google.com/group/django-users. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-users/b16ffdee-74d6-4ba2-ac1f-b5bd9cf1e40b%40googlegroups.com > > <https://groups.google.com/d/msgid/django-users/b16ffdee-74d6-4ba2-ac1f-b5bd9cf1e40b%40googlegroups.com?utm_medium=email&utm_source=footer>. > For more options, visit https://groups.google.com/d/optout. -- 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 django-users+unsubscr...@googlegroups.com. To post to this group, send email to django-users@googlegroups.com. Visit this group at https://groups.google.com/group/django-users. To view this discussion on the web visit https://groups.google.com/d/msgid/django-users/d75dee2f-d273-4d47-9d3f-859aac0e6d96%40www.fastmail.com. For more options, visit https://groups.google.com/d/optout.
