# migratio
`migratio` is a lightweight library for managing database migrations.
Core concepts:
- `migratio` supplies migration definitions with a live connection to the database, allowing more expressive migration logic than just preparing SQL statements.
- `migratio` is a code-first library, making embedding it in your application easier than other CLI-first libraries.
## Motivation
### Using a Live Database Connection
Most Rust-based migration solutions focus only on using SQL to define migration logic.
Even the ones that say they support writing migrations in Rust use Rust to simply construct SQL instructions, like [Refinery](https://github.com/rust-db/refinery/blob/main/examples/migrations/V3__add_brand_to_cars_table.rs).
Taking a hint from [Alembic](https://alembic.sqlalchemy.org/en/latest/), this library provides the user with a live connection to the database with which to define their migrations.
With a live connection, a migration can query the data, transform it in Rust, and write it back.
Migrations defined as pure SQL statements can only accomplish this with the toolkit provided by SQL, which is much more limited.
Note: [SeaORM](https://www.sea-ql.org/SeaORM/) allows this, but `migratio` aims to provide an alternative for developers that don't want to adopt a full ORM solution.
### Code-first approach
A central use case for `migratio` is embedding migration logic within an application, usually in the startup procedure.
This way, when the application updates, the next time it starts the database will automatically be migrated to the latest version without any manual intervention.
Anywhere you can construct a [SqliteMigrator](sqlite::SqliteMigrator) or [MysqlMigrator](mysql::MysqlMigrator) instance, you can access any feature this library provides.
## Benefits
- Easy adoption from other migration tools or no migration tool.
- Robust error handling and rollback support (when available).
- Preview / dry-run support.
- Migration history querying.
- Observability hooks.
- Tracing integration.
- Feature-rich testing utilities.
## Database support
- [`SQLite`](sqlite) - available with the `sqlite` feature flag.
- [`MySQL`](mysql) - available with the `mysql` feature flag.
License: MIT