Hi Django developers,
I'm new to the community and I'm not sure if this is the right place to ask my question, so please let me know if there's a more appropriate channel for this type of discussion. I am currently working on ticket #24686 and I need help. I have figured out what I think is the best way to move a model from one app to another in Django. This involves applying four separate operations in four different migrations. The operations are: 1. Rename table operation: rename the physical table name on the database 1.1. This operation should be a SeparateDatabaseAndState operation and only a database operation, and do not change any state. 2. Create table operation: Move the model code to the new app, and create a CreateModel only in state, with SeparateDatabaseAndState operation. 3. Update all foreign keys that points to the moved model 4. Delete the old model table, but only in state, using SeparateDatabaseAndState operation. I have implemented this logic in a new method on the MigrationAutodetector and called it "generate_moved_models". <https://github.com/durvalcarvalho/django/blob/b8a5155f474de8dadf92495d1ec9c668860aeb27/django/db/migrations/autodetector.py#L616> However, I am having trouble defining these operations as dependent on each other so that they are written in separate migrations. I am confused about how dependencies tuple works and how check_dependency method handle SeparateDatabaseAndState operations. For example, the dependency logic of the 4 operations looked like this: * The first operation (AlterModelTable to rename the table name on the database) only depends on the previous table creation. * [ (old_app_label, moved_model_name, None, True) ] * The second operation (the state creation of the model on the new app) depends of the The first operation (and the table creation) [ (old_app_label, moved_model_name, None, True), (old_app_label, moved_model_name, None, "alter") ] * The third operation (the foreign keys updates) will depend of the two previous operations. [ (old_app_label, moved_model_name, None, True), (old_app_label, moved_model_name, None, "alter"), (new_app_label, moved_model_name, None, True)] * Finally, the fourth operation will depend on the three previous operations, and the third operation may have generated several dependencies depending on the number of foreign keys involving the moved table. [ (old_app_label, moved_model_name, None, True), (old_app_label, moved_model_name, None, "alter"), (new_app_label, moved_model_name, None, True), (app_label_1, model_name_10, field_name_15, "alter"), (app_label_2, model_name_20, field_name_4, "alter")] If we apply this dependency logic, we can consider a scenario where there are initially only two models, such as the Tires and Cars models mentioned by João. In this situation, the migration process will generate two migration files. The file in the app where the model was moved will contain the State CreateModel operation. The remaining migration files will be located in the old app. And the strangest thing is that these two migrations depend on each other, which prevents them from being executed with the migrate command. I would appreciate any feedback on this approach and how to define the dependencies correctly. Thank you all in advance for your help. -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/31f898ae-2490-4f72-8526-ee1de3fa8e71n%40googlegroups.com.
