Question

我打破了一个节点端点，以便发生两件事

检查用户是否存在
将用户添加到数据库

controller.js

exports.signup = (req, res) => {
  methods.checkUser('email', req.body.email)
    .then(methods.addUser(req.body.email, req.body.password))
    .then(() => {
      res.send('added');
    })
    .catch((err) => {
      console.log(err);
      res.status(403).send(err);
    });
};

methods.js

exports.checkUser = (key, val) => {
  return new Promise((resolve, reject) => {
    db.query('SELECT * FROM ?? WHERE ?? = ?', ['users', key, val], (err, result) => {
      if (result) {
        resolve(result);
      } else {
        reject(err);
      }

    });
  });
};

exports.addUser = (email, password) => {
  return new Promise((resolve, reject) => {
    if (email === 'test@domain.com') {
      resolve(true);
    } else {
      console.log('rejecting');
      reject(email);
    }
  });
};

addUser()目前只检查电子邮件=== test@domain.com是否会测试Promise链。

因此端点在Postman中返回added

但终端显示以下内容

rejecting
(node:71904) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 1): bot@domain.com
(node:71904) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

通常我会这样写。

exports.signup = (req, res) => {
  methods.checkUser('email', req.body.email)
    .then(() => {
      methods.addUser(req.body.email, req.body.password)
        .then(() => {
          res.send('added');
        })
        .catch((err) => {
          res.status(403).send(err);
        })
    })
    .catch((err) => {
      console.log(err);
      res.status(403).send(err);
    });
};

我想采取更清洁的方法，但需要帮助

Answer 1

这是编写Promise链的正确方法：

exports.signup = (req, res) => {
    methods.checkUser('email', req.body.email)
      .then(() => methods.addUser(req.body.email, req.body.password) )
      .then(() => res.send('added') )
      .catch((err) => {
        console.log(err);
        res.status(403).send(err);
      });
  };

因此，如果链中有reject，就像示例中email=bot@domain.com输入的情况一样，拒绝将由最后catch处理。

Node Express链接函数返回UnhandledPromiseRejectionWarning

1 个答案: