用postgres默认为mysql

我正在设置Sequelize来pipe理Node.js应用程序中的postgres。

我需要sequelize-postgres，以及在实例化新的Sequelize对象时在方言attr中声明“postgres”。 但由于某种原因，它默认使用mysql。

确切的错误信息：

/Users/...project/node_modules/sequelize/lib/dialects/mysql/connector-manager.js:306 var connection = mysql.createConnection(connectionConfig); ^ TypeError: Cannot call method 'createConnection' of undefined at module.exports.connect (.../node_modules/sequelize/lib/dialects/mysql/connector-manager.js:306:28) at Object.pool.Pooling.Pool.create (.../node_modules/sequelize/lib/dialects/mysql/connector-manager.js:131:19) at createResource (.../node_modules/sequelize/node_modules/generic-pool/lib/generic-pool.js:258:13) at dispense (.../node_modules/sequelize/node_modules/generic-pool/lib/generic-pool.js:250:9) at Object.me.acquire (.../node_modules/sequelize/node_modules/generic-pool/lib/generic-pool.js:316:5) at null.fct (.../node_modules/sequelize/lib/dialects/mysql/connector-manager.js:241:19) at null.<anonymous> (.../node_modules/sequelize/lib/emitters/custom-event-emitter.js:24:18) at processImmediate [as _immediateCallback] (timers.js:336:15) 

任何帮助表示感谢，谢谢！