Struct MigrationChain 

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

A chain of migrations that can upgrade state through multiple versions.

Design

The migration chain executes migrations in sequence, starting from the stored version and ending at the current version. Each step increments the version by exactly one.

Example

let mut chain = MigrationChain::<FinalState>::new();
chain.register(Box::new(V1ToV2Migration));
chain.register(Box::new(V2ToV3Migration));

// Migrate from v1 to v3 (current)
let result = chain.migrate_to_current(v1_state, 1, 3);

Implementations

impl<S: 'static> MigrationChain<S>

pub fn new() -> Self

Create an empty migration chain.

pub fn register(&mut self, migration: Box<dyn ErasedMigration<S>>)

Register a migration step.

Panics

Panics if a migration for the same from_version is already registered.

pub fn has_path(&self, from_version: u32, to_version: u32) -> bool

Check if a migration path exists from from_version to to_version.

pub fn migrate( &self, state: Box<dyn Any + Send>, from_version: u32, to_version: u32, ) -> Result<Box<dyn Any + Send>, MigrationError>

Attempt to migrate state from from_version to to_version.

Returns Ok(migrated_state) on success, or Err if migration fails.

Trait Implementations

impl<S: 'static> Default for MigrationChain<S>

fn default() -> Self

Returns the “default value” for a type.