This crate is a very lightweight migration framework. It simply runs a series of sql commands in succession. It is not sophisticated.
Let's take a look at the built-in migration that the crate uses to create the table:
rust
pub fn migration() -> Migration {
Migration::new(NAME)
.with_up(
r#"
CREATE TABLE migrations (
name TEXT NOT NULL PRIMARY KEY,
executed_at TIMESTAMPTZ NOT NULL DEFAULT now()
)
"#,
)
.with_down(
r#"
DROP TABLE IF EXISTS migrations
"#,
)
}
Right now, it's hard coded against TIMESTAMPTZ making this crate only suitable for Postgres. @ecton is only using this crate with Postgres, but would welcome any contributions to make this more generic.
Each with_up call is executed in the order it is added to the Migration structure. When rolling back a migration, the with_down instructions are operated in reverse order. This allows you to write with_up and with_down on a single-structure basis like the example above shows, keeping the up and down logic close together.
If you're working on a migration and want it to execute every time, just add .debug() to the builder pattern before returning it. debug() is not enabled on builds without cfg(debug_assertions) ensuring that if you build with --release for deploying, you will never accidentally deploy a migration that was still marked as being debugged.
Lastly, if you want to test rebuilding the database from scratch, you can use .nuclear_debug() instead, which will force every run to undo all migrations and redo them.
The pattern for executing migrations looks like this:
```rust
pub fn migrations() -> Vec
pub async fn runall() -> Result<(), MigrationError> { let pool = connectto_postgres();
Migration::run_all(&pool, migrations()).await
} ```