stringtree-migrate-driver-postgres.js

const pg = require('pg');

module.exports = function (options) {
  return {
    open: function (cb) {
      const self = this;
      if (!self.client) {
        new pg.Client(options).connect(function (err, _client) {
          if (err) return cb(err);
          self.client = _client;
          cb(null, _client);
        });
      } else {
        cb(null, self.client);
      }
    },

    close: function (cb) {
      const self = this;
      if (!self.client) return cb();
      self.client.end();
      delete self.client;
      cb();
    },

    check: function (cb) {
      this.execute('select * from pg_catalog.pg_tables where tablename LIKE \'st_migrate\'', function (err, tables) {
        if (err) return cb(err);
        if (!tables) return cb(new Error('could not read table data from db'));
        cb(null, tables[0]);
      });
    },

    create: function (cb) {
      this.execute('create table st_migrate ( level integer )', cb);
    },

    current: function (cb) {
      this.execute('select level from st_migrate order by level desc', function (err, levels) {
        if (err) return cb(err);
        const current = levels[0] || { level: 0 };
        cb(null, current.level);
      });
    },

    update: function (level, cb) {
      this.execute('insert into st_migrate (level) values ($1)', [level], cb);
    },

    execute: function (sql, params, cb) {
      if (arguments.length === 2) return this.execute(arguments[0], [], arguments[1]);
      this.client.query(sql, params, function (err, result) {
        if (err) return cb(err);
        cb(err, result.rows);
      });
    }
  };
};