Generate migration code from entities

[JUNGYU-RIM1]

Summary

sea-orm-cli migrate init should generate migration files from entities

In this example setting-up-migration, sea-orm only generate m20220101_000001_create_table.rs which is a sample migration file. If there are pre-defined entities, it should generate those migration files too(in this case m20220120_000001_create_post_table.rs).

In the case of the maintenance phase, generating an alter_table file is also needed. If a certain entity is changed, it should find the create_table file of that entity, and based on that file, the alter_table file should be generated.

Motivation

Currently, if I use the code-first approach in sea-orm, I should write code to generate tables that fit into my entities. There are several problems with that

• There is the possibility that I mismatch entities and code.
• If I change the entity, I should change the migration code too

So I think that adding this feature will help both error-prune and develop performance

Additional Information

• EF in c# support this feature
• Prisma in Node.js also support similar feature

[mojerro]

Hope has this feature too, just like #332 , I really hope to have a function like auto_migrate() which is very convenient when developing.

Now, my project has 16 tables which are really hard to write migration files by hand, and I need to spend lots of time checking and ensuring the code runs correctly.