Sqlite migrations for react native for use with react-native-sqlite-storage and react-native-sqlite-2

react-native-sqlite-migrations.js

/** 
 * this class decides what migrations to run and runs them
 */
class RNSqliteMigrator {
  constructor(db) {
    this._db = db;

    this.initialize();
    this._migrationsMap = {};
    this._versions = [];
    this._cursor = 0;
  }

  _next(e) {
    if (this._versions[this._cursor]) {
      const next = this._versions[this._cursor];
      this._migrationsMap[next].execute(this._db, () => {
        this._cursor++;
        this._next();
      });
    } else {
      // done!
      this._cursor = 0;
      // update version stored in the database to current version
      this._db.transaction(txn => {
        txn.executeSql("UPDATE version SET version = :version", [this._db.version]);
      });
    }
  }

  initialize() {
    this._db.transaction(txn => {
      txn.executeSql("SELECT name FROM sqlite_master WHERE type='table' AND name=:name", ['version'], (tx, result) => {
        if (!result.rows.length) {
          tx.executeSql('CREATE TABLE IF NOT EXISTS version (version INTEGER)');
          tx.executeSql('CREATE INDEX IF NOT EXISTS version_idx ON version (version);');
          tx.executeSql('INSERT INTO version (version) VALUES (:version)', [0]);
          tx.executeSql('CREATE TABLE IF NOT EXISTS executed_migrations (migration INTEGER)');
          tx.executeSql('CREATE INDEX IF NOT EXISTS migration_idx ON executed_migrations (migration);')
          this.currentVersion = 0;
        } else {
          tx.executeSql('SELECT version FROM version LIMIT 1', [], (tx, result) => {
            this.currentVersion = result.rows.item(0).version;
          });
        }
      });
    }, error => console.error(error), this.migrate.bind(this));
  }

  migrate() {
    if (typeof this.currentVersion === 'undefined') return; // haven't initialized yet

    if (this._cursor === 0 && this.currentVersion < this._db.version) {
      let found = false;
      for (let i = 0; i < this._versions.length && !found; i++) {
        if (this.currentVersion >= this._versions[i]) {
          this._cursor = i + 1;
        } else {
          found = true;
        }
      }

      // call migrations
      this._next();
    }
  }

  up(migration) {
    if (this._migrationsMap[migration.version]) throw new Error('Migration with that version number already exists');
    this._migrationsMap[migration.version] = migration;

    this._versions.push(migration.version);
    this._versions.sort((a, b) => a - b);
  }
}

/**
 * extend this to make new migrations
 */
import { Sentry } from 'react-native-sentry';

class RNSqliteMigration {
  constructor(version, sql) {
    this.version = version;
    this.sql = sql;
  }

  execute = (db, next) => {
    function exec(tx, sql) {
      tx.executeSql(sql);
    }

    db.transaction(txn => {
      txn.executeSql("SELECT migration FROM executed_migrations WHERE migration=:migration", [this.version], (tx, result) => {
        if (!result.rows.length) {
          if (Array.isArray(this.sql)) {
            this.sql.forEach(s => exec(tx, s));
          } else {
            exec(tx, this.sql);
          }
          tx.executeSql('INSERT INTO executed_migrations (migration) VALUES (:migration)', [this.version]);
        }
      });
    }, error => {
      Sentry.captureException(error, { logger: 'sqlite.migrations' });
      next(error);
    }, next);
  }
}


/**
 * USAGE
 */
import db from '../db' // connection for react-native-sqlite-storage OR react-native-sqlite-2

const makeTable = `
  CREATE TABLE test (
    field TEXT
  )
`;

const alterTable = `
  ALTER TABLE test ADD COLUMN another_field TEXT
`;

const migrations = [
  new RNSqliteMigration(1, makeTable),
  new RNSqliteMigration(2, makeAnotherTable),
];

const migrator = new RNSqliteMigrator(db);
migrator.up(RNSqliteMigration(1, makeTable))
migrator.up(RNSqliteMigration(2, alterTable))

// attempt to run migrations anytime the app state changes to active
// if there are new migrations to run (ie, your user has updated the app
// and there are new migrations) then the migrator will run only those
// migrations
AppState.addEventListener('change', () => {
  if (AppState.currentState === 'active') {
    migrator.migrate();
  }
});

The this._db.version is supposed to be the latest version of your database. The version is actually the length or total number of your migrations: migrations.length. So you can set a version property on your db object to be db.version = migrations.length. Another option is to set the db version in the execute method of the RNSqliteMigration class. Just before line 96, this line: if (!result.rows.length) {, you can add db.version = this.version.