Struct Migration 

pub struct Migration {
    pub id: &'static str,
    pub up_sql: &'static str,
    pub down_sql: Option<&'static str>,
    pub is_already_applied: Option<fn(&Connection) -> bool>,
}

A single legacy migration step within a ServiceSchemaPlan.

Fields

id: &'static str

Unique identifier for this migration.

up_sql: &'static str

SQL to apply (forward direction).

down_sql: Option<&'static str>

SQL to revert (optional).

is_already_applied: Option<fn(&Connection) -> bool>

Optional predicate: returns true if migration was already applied through a mechanism other than the migration tracker.