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I'm looking at the "Hello Slick" tutorial. A users table is defined and then created using users.schema.create (the code on github is outdated so there it's users.ddl.create there, but when I create the app in Activator it's schema because it's using Slick 3.0.0, which is close enough). However if I run the app a second time there's an error because the table already exists. I see no option like users.schema.createIfNotExists which is a bit surprising. But in any case I would need something more sophisticated if I added a column to the table sometime in the future. So does Slick have no way of helping with migrations/evolutions?

I'm using Play and supposedly Play Slick has special support for database evolutions. It's not clear what is offered in addition to the usual Play evolutions that is specific to Slick: we're just told to add a dependency. I can't see any further documentation.

Do I have to manually write the SQL for evolutions (1.sql, Ups, Downs, etc.)? If so it seems pretty silly to have to write code like column[Int]("ID", O.PrimaryKey, O.AutoInc) in addition. I'm bothered by the duplication of effort and worried that if my SQL/DDL is wrong subtle bugs will appear when I access the database. I may be wrong but I seem to remember that migrations can be automatically generated after changing a model in Django so it doesn't seem like an unsolvable problem. Is this just not something that's been implemented or am I missing something?

I'm using PostgreSQL if that's relevant.

Joan
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Alex Hall
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1 Answers1

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You could use slicks schema code generation feature:

http://slick.typesafe.com/doc/3.0.0/code-generation.html

This way if you update the db schema, you don't have to hand write the slick classes to correspond with the table this will just do it for you.

Laurence Bird
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