forked from akai/readest
Huang Xin
78 lines
2.5 KiB
TypeScript
78 lines
2.5 KiB
TypeScript
import { DatabaseService } from '@/types/database';
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export interface MigrationEntry {
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/** Migration name, e.g. "2026030601_initial_schema" */
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name: string;
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/** SQL statements separated by semicolons */
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sql: string;
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}
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/**
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* Discriminator for databases with different schemas.
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* Add new schema types here as needed.
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*/
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export type SchemaType = string;
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export interface MigrateOptions {
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/** Name of the tracking table. @default '__migrations' */
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table?: string;
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}
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/**
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* Run pending migrations against a DatabaseService instance.
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*
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* Uses PRAGMA user_version as an O(1) fast-path to skip migration checks
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* when the database is already at the latest version. This makes it cheap
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* to call on every openDatabase(), even with hundreds of database files.
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*
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* Each migration runs atomically via batch() — the schema changes and
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* the tracking record are committed together.
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*/
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export async function migrate(
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db: DatabaseService,
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migrations: MigrationEntry[],
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options: MigrateOptions = {},
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): Promise<void> {
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const targetVersion = migrations.length;
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if (targetVersion === 0) return;
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// Fast path: PRAGMA user_version is stored in the file header.
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// Reading it requires no table scan — essentially free.
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const rows = await db.select<{ user_version: number }>('PRAGMA user_version');
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const currentVersion = rows[0]?.user_version ?? 0;
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if (currentVersion >= targetVersion) return;
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const table = options.table ?? '__migrations';
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// Ensure tracking table exists (only reached when migrations are needed)
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await db.execute(
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`CREATE TABLE IF NOT EXISTS ${table} (
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id INTEGER PRIMARY KEY AUTOINCREMENT,
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name TEXT NOT NULL UNIQUE,
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applied_at DATETIME DEFAULT CURRENT_TIMESTAMP
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)`,
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);
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// Get already-applied migration names
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const applied = await db.select<{ name: string }>(`SELECT name FROM ${table}`);
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const appliedSet = new Set(applied.map((r) => r.name));
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// Apply pending migrations in order
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for (let i = 0; i < migrations.length; i++) {
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const migration = migrations[i]!;
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if (appliedSet.has(migration.name)) continue;
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const statements = migration.sql
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.split(';')
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.map((s) => s.trim())
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.filter((s) => s.length > 0);
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// Record the migration and bump user_version atomically
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const safeName = migration.name.replace(/'/g, "''");
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statements.push(`INSERT INTO ${table} (name) VALUES ('${safeName}')`);
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statements.push(`PRAGMA user_version = ${i + 1}`);
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await db.batch(statements);
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}
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}
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