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Thanks! FWIW, structure.sql is not needed in Ecto either. You must do that when: 1. You want to start discarding migrations (because you have too many) 2. You

Thanks! FWIW, structure.sql is not needed in Ecto either. You must do that when: 1. You want to start discarding migrations (because you have too many) 2. You had an existing database Are those never a "trigger" on Django side? I appreciate the opportunity to learn!

maxmorlocke 4y ago
Generally speaking, it's inadvisable to 'discard' migrations with django. If the migration set is getting too large, the general practice is to 'squash' migrations, which is a django-supported function for merging the migrations down to a single app. You can do the less blessed, but more simple function of nuking the migrations, updating the migrations table, and remaking your migrations... but you have to coordinate that in every environment. For an existing database, you can easily create django models for each table, etc. There's a --fake option to update the migration table to make it think you've applied these migrations, but not actually apply them. This convinces django you've brought the database in sync. May your deity or deities help you if you did not actually bring it in sync. I've used this quite a bit in some java ee->python migrations I've done in the past.
ralmidani 4y ago
TIL you actually don’t need structure.sql for Ecto! In that case, discarding migrations on a large running app seems like a not-always-good practice, right? FWIW, my experience with Ecto has always been in joining existing codebases that are already big. I do also want to add that Django can kind of do the reverse of auto-generating migrations: it can “inspect” an existing database and generate Python classes that allow you to use the Django API as if you wrote those classes yourself: https://docs.djangoproject.com/en/4.1/howto/legacy-databases/ https://docs.djangoproject.com/en/4.1/howto/legacy-databases... Of course, the feature is not going to be perfect, especially if a team has been using odd naming conventions in the legacy database, but it seems helpful at least in theory.
- bostonvaulter2 4y ago
  Inspecting a database and coming up with models is a frequent pain point that I see new elixir devs experiencing. I’d love to see someone take a stab at generators for that. I wonder if someone would do an integration for https://ash-hq.org/ https://ash-hq.org/ that does that.

maxmorlocke 4y ago

Generally speaking, it's inadvisable to 'discard' migrations with django. If the migration set is getting too large, the general practice is to 'squash' migrations, which is a django-supported function for merging the migrations down to a single app. You can do the less blessed, but more simple function of nuking the migrations, updating the migrations table, and remaking your migrations... but you have to coordinate that in every environment. For an existing database, you can easily create django models for each table, etc. There's a --fake option to update the migration table to make it think you've applied these migrations, but not actually apply them. This convinces django you've brought the database in sync. May your deity or deities help you if you did not actually bring it in sync. I've used this quite a bit in some java ee->python migrations I've done in the past.

ralmidani 4y ago

TIL you actually don’t need structure.sql for Ecto! In that case, discarding migrations on a large running app seems like a not-always-good practice, right? FWIW, my experience with Ecto has always been in joining existing codebases that are already big. I do also want to add that Django can kind of do the reverse of auto-generating migrations: it can “inspect” an existing database and generate Python classes that allow you to use the Django API as if you wrote those classes yourself: https://docs.djangoproject.com/en/4.1/howto/legacy-databases/ https://docs.djangoproject.com/en/4.1/howto/legacy-databases... Of course, the feature is not going to be perfect, especially if a team has been using odd naming conventions in the legacy database, but it seems helpful at least in theory.

bostonvaulter2 4y ago
Inspecting a database and coming up with models is a frequent pain point that I see new elixir devs experiencing. I’d love to see someone take a stab at generators for that. I wonder if someone would do an integration for https://ash-hq.org/ https://ash-hq.org/ that does that.