TypeError：app.post（…）。然后不是一个函数

Question

I am having some problems with my API routes in a node App. I switched the 'to' portion of my Nodemailer and now all of a sudden it is giving me problems with the Async in my 'Post' Action.

I keep getting an error mesage: 'TypeError: app.post(...).then is not a function'

Here is the code:

app.post("/api/applicants", function(req, res) {
  db.Applicant.create(req.body);
  res.send('Successfully posted new Applicant');       
  }).then(function(appPost){
      //mail details for nodemailer
      let mailOptions = {
          from: '"noreply@cap.org" <app@cap.org>', // sender address
          to: 'ijvv7dth54f7zp3w@ethereal.email', // list of receivers
          subject: 'Application Submitted', // Subject line
          text: req.body.firstname + ' ' + req.body.last_name + ' just sent you a message!', // plain text body
          html: '<b>'+req.body.first_name+'</b>' + '</br>' +
          ''  + req.body.last_name   + '</br>' + 
          'DOB: ' 
           // html body
      };
      transporter.sendMail(mailOptions, (error, info) => {
          if (error) {
              return console.log(error);
          }
          console.log('Message sent: %s', info.messageId);
          // Preview only available when sending through an Ethereal account
          console.log('Preview URL: %s', nodemailer.getTestMessageUrl(info));
          // Message sent: <b658f8ca-6296-ccf4-8306-87d57a0b4321@blurdybloop.com>
          // Preview URL: https://ethereal.email/message/WaQKMgKddxQDoou...
      }); 
   });

Answer 1

It seems you've attached a .then promise handler to app.post . app.post is provided by Express and does not return a promise, instead it consumes a handler function.

It looks like you actually intended for your promise to come from db.Applicant.create instead. In this case you will need to take your .then promise and put it following the db.Applicant.create like this.

app.post("/api/applicants", function(req, res) {
  return db.Applicant.create(req.body).then(function(appPost){
    // Respond to the HTTP request
    res.send('Successfully posted new Applicant');
    res.end(); // Ensure the response is sent before any emailing is attempted

    //mail details for nodemailer
    let mailOptions = {
      from: '"noreply@cap.org" <app@cap.org>', // sender address
      to: 'ijvv7dth54f7zp3w@ethereal.email', // list of receivers
      subject: 'Application Submitted', // Subject line
      text: req.body.firstname + ' ' + req.body.last_name + ' just sent you a message!', // plain text body
      html: '<b>'+req.body.first_name+'</b>' + '</br>' +
      ''  + req.body.last_name   + '</br>' +
      'DOB: '
      // html body
    };
    transporter.sendMail(mailOptions, (error, info) => {
      if (error) {
        return console.log(error);
      }
      console.log('Message sent: %s', info.messageId);
      // Preview only available when sending through an Ethereal account
      console.log('Preview URL: %s', nodemailer.getTestMessageUrl(info));
      // Message sent: <b658f8ca-6296-ccf4-8306-87d57a0b4321@blurdybloop.com>
      // Preview URL: https://ethereal.email/message/WaQKMgKddxQDoou...
    });
  });
});

In this case I'm assuming that db.Applicant.create returns a promise, though it is not possible to know for sure without knowing the packages you're using. Also, notice that I added "res.end()" which will close the HTTP response before attempting the email code, this is optional but should ensure the client gets a response before the email is processed. You may, or may not want to do this as well.