migratio 0.4.2

Write expressive database migrations in Rust.
Documentation 
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#![cfg_attr(docsrs, feature(doc_cfg))]
//! `migratio` is a library for managing database migrations.
//!
//! Core concepts:
//! - Live DB Connections: `migratio` supplies migration definitions with a live connection to the database, allowing more expressive migration logic than just preparing SQL statements.
//! - Code-First: `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.
//!
//! # 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 = available with the `tracing` feature flag.
//! - Testing utilities - available with the `testing` feature flag.
//!
//! # Database support
//!
//! - [`SQLite`](sqlite) - available with the `sqlite` feature flag.
//! - [`MySQL`](mysql) - available with the `mysql` feature flag.
//! - [`PostgreSQL`](postgres) - available with the `postgres` feature flag.

mod core;
pub use core::{
    AppliedMigration, Migration, MigrationFailure, MigrationReport, MigrationType, Precondition,
};

mod error;
pub use error::Error;

#[macro_use]
mod macros;

#[cfg(feature = "sqlite")]
#[cfg_attr(docsrs, doc(cfg(feature = "sqlite")))]
pub mod sqlite;

#[cfg(feature = "mysql")]
pub mod mysql;

#[cfg(feature = "postgres")]
#[cfg_attr(docsrs, doc(cfg(feature = "postgres")))]
pub mod postgres;

#[cfg(feature = "testing")]
pub mod testing;

#[cfg(all(test, feature = "mysql"))]
pub(crate) mod test_mysql;

#[cfg(all(test, feature = "postgres"))]
pub(crate) mod test_postgres;