Struct Migrator 

pub struct Migrator { /* private fields */ }

The migration manager that orchestrates all migrations.

Implementations

impl Migrator

pub fn new() -> Self

Creates a new, empty migrator.

pub fn define(entity: &str) -> MigrationPathBuilder<Start>

Starts defining a migration path for an entity.

pub fn register<D>( &mut self, path: MigrationPath<D>, ) -> Result<(), MigrationError>

Registers a migration path with validation.

This method validates the migration path before registering it:

• Checks for circular migration paths
• Validates version ordering follows semver rules

Errors

Returns an error if validation fails.

pub fn load_from<D, T>( &self, entity: &str, data: T, ) -> Result<D, MigrationError>

where D: DeserializeOwned, T: Serialize,

Loads and migrates data from any serde-compatible format.

This is the generic version that accepts any type implementing Serialize. For JSON strings, use the convenience method load instead.

Arguments

• entity - The entity name used when registering the migration path
• data - Versioned data in any serde-compatible format (e.g., toml::Value, serde_json::Value)

Returns

The migrated data as the domain model type

Errors

Returns an error if:

• The data cannot be converted to the internal format
• The entity is not registered
• A migration step fails

Example

// Load from TOML
let toml_data: toml::Value = toml::from_str(toml_str)?;
let domain: TaskEntity = migrator.load_from("task", toml_data)?;

// Load from JSON Value
let json_data: serde_json::Value = serde_json::from_str(json_str)?;
let domain: TaskEntity = migrator.load_from("task", json_data)?;

pub fn load<D: DeserializeOwned>( &self, entity: &str, json: &str, ) -> Result<D, MigrationError>

Loads and migrates data from a JSON string.

This is a convenience method for the common case of loading from JSON. For other formats, use load_from instead.

Arguments

• entity - The entity name used when registering the migration path
• json - A JSON string containing versioned data

Returns

The migrated data as the domain model type

Errors

Returns an error if:

• The JSON cannot be parsed
• The entity is not registered
• A migration step fails

Example

let json = r#"{"version":"1.0.0","data":{"id":"task-1","title":"My Task"}}"#;
let domain: TaskEntity = migrator.load("task", json)?;

pub fn save<T: Versioned + Serialize>( &self, data: T, ) -> Result<String, MigrationError>

Saves versioned data to a JSON string.

This method wraps the provided data with its version information and serializes it to JSON format. The resulting JSON can later be loaded and migrated using the load method.

Arguments

• data - The versioned data to save

Returns

A JSON string with the format: {"version":"x.y.z","data":{...}}

Errors

Returns SerializationError if the data cannot be serialized to JSON.

Example

let task = TaskV1_0_0 {
    id: "task-1".to_string(),
    title: "My Task".to_string(),
};

let migrator = Migrator::new();
let json = migrator.save(task)?;
// json: {"version":"1.0.0","data":{"id":"task-1","title":"My Task"}}

Trait Implementations

impl Default for Migrator

fn default() -> Self

Returns the “default value” for a type.