处理promise.reject尝试catch或promise.catch

我对承诺的理解并不完美。
所以我不确定哪个代码是正确的方式来处理错误和exception情况。

请帮我写正确的代码。

1。 尝试 – 赶上续集者的诺言

async function doGetAdminList(adminName) { let adminList; try { adminList = await sequelize.query( sqls.GET_ADMIN_LIST, { replacements: { adminName: adminName }, type: sequelize.QueryTypes.SELECT } ); } catch (e) { return Promise.reject({status:500, message: "SQL Error" }); } if (!adminList || !Object.keys(adminList).length) { log.info('\nadminList not found :\n'); return Promise.reject({status:400, message: 'adminList not found.' }) } return adminList; } 

为此，我想知道try-catch是否能够捕获续集器的promise.catch（）。

第2位。 不要处理续集器的promise.reject

 async function doGetAdminList(adminName) { let adminList; adminList = await sequelize.query( sqls.GET_ADMIN_LIST, { replacements: { adminName: adminName }, type: sequelize.QueryTypes.SELECT } ); if (!adminList || !Object.keys(adminList).length) { log.info('\nadminList not found :\n'); return Promise.reject({status:400, message: 'adminList not found.' }) } return adminList; } 

为此，我不知道sequelizer的promise.reject（）是否可以通过调用者函数并在promise.catch（）函数中捕获调用者。

以上使用函数将在以下expression函数中使用。

adminController.js

 const jwtAuth = require('../common/jwtAuth.js'); exports.getAdminList = function (req, res) { res.setHeader("Content-Type", "application/json; charset=utf-8"); if (!req.body.adminName) { return res.status(400).json({ message: 'adminName is empty.' }); } jwtAuth(req.headers.accesstoken) .then((decoded) => { worker = decoded.loginName; return doGetAdminList(adminName); }) .then((adminList) => { log.info("getAdminList() finish"); res.status(200).json(adminList); }) .catch(e => { log.error(e); return res.status(e.status).json(e); }); }; 

jwtAuth.js也是promise函数。

 const jwt = require('jsonwebtoken'); module.exports = async function verifyJwt(token) { return await new Promise((resolve, reject) => { if (!token) { reject({status:401, message:'Empty token'}); return; } jwt.verify(token,"dipa",function(err, decoded){ if(err) { reject({status:401, message:'TokenExpiredError'}); } else { resolve(decoded); } }); }); } 

Answer 1

如果你的函数返回一个promise，就不需要使用“async”，因为async函数返回一个Promise 。

我的意思是， var somethink = await doSomethink()的结果是var somethink = await doSomethink()它不是承诺它的对象，因为你从一个async函数返回它作为Promise.resolve(somethink )返回。

所以你的'jwtAuth.js'更好没有

 const jwt = require('jsonwebtoken'); module.exports = function verifyJwt(token) { return new Promise((resolve, reject) => { if (!token) { reject({status:401, message:'Empty token'}); return; } jwt.verify(token,"dipa",function(err, decoded){ if(err) { reject({status:401, message:'TokenExpiredError'}); } else { resolve(decoded); } }); }); } 

同样如此

 function doGetAdminList(adminName) { let adminList; return sequelize.query( sqls.GET_ADMIN_LIST, { replacements: { adminName: adminName }, type: sequelize.QueryTypes.SELECT } ).catch((e)=> { //here you catch you sequelize error which can be anything //you can either catch and throw a new Error log.info('\nadminList not found :\n'); throw Error({ status: 500, message: "SQL Error" }) }) } 

关于getAdminList和最后的catch 。

如果jwtAuth或doGetAdminList引发错误.catch将收到错误。

如果在doGetAdminList您不会在.catch上sequelize.query那么sequelize error将会传播到您的catch中。 但是，如果你想处理错误，并重新抛出错误是可能的。

 const jwtAuth = require('../common/jwtAuth.js'); exports.getAdminList = function (req, res) { res.setHeader("Content-Type", "application/json; charset=utf-8"); if (!req.body.adminName) { res.status(400).json({ message: 'adminName is empty.' }); } jwtAuth(req.headers.accesstoken) .then((decoded) => { worker = decoded.loginName; return doGetAdminList(adminName); }) .then((adminList) => { log.info("getAdminList() finish"); res.status(200).json(adminList); }) .catch(e => { //the message with mess "SQL Error" will travel here. log.error(e); res.status(e.status).json(e); }); }; 

添加，如果你不想改变错误，但是你想logging和处理错误，你可以重新抛出它

 .catch(function(e) { log.info('\nadminList not found :\n'); throw e; }) 

另外，如果你想做async/await getAdminList

 exports.getAdminList = async function(req, res) { res.setHeader("Content-Type", "application/json; charset=utf-8"); if (!req.body.adminName) res.status(400).json({message: 'adminName is empty.'}); try { let decoded = await jwtAuth(req.headers.accesstoken) worker = decoded.loginName; let adminList = await doGetAdminList(req.body.adminName); log.info("getAdminList() finish"); res.status(200).json(adminList); } catch (e) { //the message with mess "SQL Error" will travel here. log.error(e); res.status(e.status).json(e); } };