node.js - 将promise.reject处理为try-catch或promise.catch

Question

我对 Promise 的理解并不完美。
所以我不确定哪种代码是处理错误和异常情况的正确方法。

请帮助我正确编写代码。

第一。 try - catch Sequelize 的promise.reject

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是否可以捕获sequelizer的promise.catch()。

第二。不处理sequelizer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，我想知道sequelizer的promise.reject()是否可以传递调用者函数并在promise.catch()处捕获调用者的函数。

上面的sequelize-using函数将在下面的express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

如果您的函数返回 Promise，则无需使用“async”，因为 async 函数返回 Promise。

我的意思是， var somethink = wait doSomethink() 的结果不是一个 promise ，它是一个对象，因为你从一个 async 函数返回它，所以它返回如Promise.resolve(somethink)。

所以你的“jwtAuth.js”没有更好

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);
      }
    });
  }); 
}

同样的情况

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抛出错误.catch将收到错误。

如果在 doGetAdminList 中，您没有对 sequelize.query 执行 .catch，那么 sequelize 错误 将传至你的捕获就在这里。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，如果您不想更改错误，但想记录并绕过错误，则可以重新抛出它

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

此外，如果您想使用 async/await 执行 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);
  }

};