Struct Migrator 

pub struct Migrator<S> { /* private fields */ }

Migrator is used to apply database migrations.

Create it with Database::migrator.

When all migrations are done, it can be turned into a Database instance with Migrator::finish.

Implementations

impl<S: Schema> Migrator<S>

pub fn migrate<'x, M>( self, m: impl Send + FnOnce(&mut TransactionMigrate<S>) -> M, ) -> Migrator<M::To>

where M: SchemaMigration<'x, From = S>,

Apply a database migration if the current schema is S and return a Migrator for the next schema N.

This function will panic if the schema on disk does not match what is expected for its user_version.

#[schema(Schema)]
#[version(0..=1)]
pub mod vN {
    pub struct User {
        pub name: String,
        #[version(1..)]
        pub score: i64,
    }
}

fn main() {
    Database::migrator(Config::open_in_memory())
        .unwrap()
        .migrate(|txn| v0::migrate::Schema {
            user: txn.migrate_ok(|old: Lazy<v0::User>| v0::migrate::User {
                score: old.name.len() as i64,
            }),
        })
        .finish()
        .unwrap();
}

pub fn fixup(self, f: impl Send + FnOnce(&'static mut Transaction<S>)) -> Self

Mutate the database as part of migrations.

The closure will only be executed if the database got migrated to schema version S by this Migrator instance. If Migrator::fixup is used before all Migrator::migrate, then the closures is only executed when the database is created.

pub fn finish(self) -> Option<Database<S>>

Commit the migration transaction and return a Database.

Returns None if the database schema version is newer than S.

This function will panic if the schema on disk does not match what is expected for its user_version.