Creé algunas funciones en el mismo archivo index.js, que essendEmail, sendEmailByDbStatusChange ysendEmailConfirmation.

sendEmail - Para ser llamado a través de HTTP / API

sendEmailByDbStatusChange - escuchando DB mientras cambia el valor, pero la acción está codificada

sendEmailConfirmation - Listado en DB mientras el cambio de valor, la acción está sujeta a la instantánea.

Abajo están mis códigos:

const functions = require('firebase-functions');
const nodemailer = require('nodemailer');
const gmailEmail = functions.config().gmail.email;
const gmailPassword = functions.config().gmail.password;
const mailTransport = nodemailer.createTransport({
  service: 'gmail',
  auth: {
    user: gmailEmail,
    pass: gmailPassword,
  },
});

// Sends an email confirmation when a user changes his mailing list subscription.
exports.sendEmail = functions.https.onRequest((req, res) => {
  if (req.body.subject === undefined || req.body.recipient === undefined) {
    // This is an error case, as "message" is required.
    //res.status(400).send('subject/body/recipient is missing!');
    return false
  } else {
    const mailSubject = req.body.subject;
    const mailHtmlBody = req.body.htmlBody;
    const mailRecipient = req.body.recipient;



    const mailOptions = {
      from: '"Food Ninja." <[email protected]>',
      to: mailRecipient,
      subject: mailSubject,
      html: mailHtmlBody
    };

    //res.status(200).send('Success: ' + mailSubject + ' to ' + mailRecipient);

    return mailTransport.sendMail(mailOptions)
      .then(() => {
        console.log(`${mailSubject}subscription confirmation email sent to: `, mailRecipient)
        return res.status(200).send('Success: ' + mailSubject + ' to ' + mailRecipient)
      })
      .catch((error) => console.error('There was an error while sending the email:', error));
  }
});

exports.sendEmailByDbStatusChange = functions.database.ref('/users/{uid}').onWrite((event) => {
  //const snapshot = event.data;
  //const val = snapshot.val();

  //if (!snapshot.changed('subscribedToMailingList')) {
  //  return null;
  //}

  const mailSubject = 'Sending email with Cloud Function - by DB onWrite Trigger';
  const mailHtmlBody = '<h1>Hello Jerry</h1><p>If you receiving this means that you have successfully deployed a customized firebase function</p><p>Be Happy!<br><br>Food Ninja Team</p>';
  const mailRecipient = '[email protected]';

  const mailOptions = {
    from: '"Food Ninja." <[email protected]>',
    to: mailRecipient,
    subject: mailSubject,
    html: mailHtmlBody
  };

  //const subscribed = val.subscribedToMailingList;

  // Building Email message.
  //mailOptions.subject = subscribed ? 'Thanks and Welcome!' : 'Sad to see you go :`(';
  //mailOptions.text = subscribed ? 'Thanks you for subscribing to our newsletter. You will receive our next weekly newsletter.' : 'I hereby confirm that I will stop sending you the newsletter.';

  return mailTransport.sendMail(mailOptions)
    .then(() =>
      console.log(`${mailSubject}subscription confirmation email sent to: `, mailRecipient)
      //return res.status(200).send('Success: ' + mailSubject + ' to ' + mailRecipient)
    )
    .catch((error) => console.error('There was an error while sending the email:', error));
});

exports.sendEmailConfirmation = functions.database.ref('/users/{uid}').onWrite((event2) => {
  console.log(event2)
  console.log(event2.val())
  console.log(event2.val().data)
  console.log(event2.data)
  console.log(event2.data.val())
  const snapshot = event2.data;
  console.log(snapshot)
  const val = snapshot.val();
  console.log(val)

  if (!snapshot.changed('subscribedToMailingList')) {
    return null;
  }

  const mailOptions = {
    from: '"Spammy Corp." <[email protected]>',
    to: val.email,
  };

  const subscribed = val.subscribedToMailingList;

  // Building Email message.
  mailOptions.subject = subscribed ? 'Thanks and Welcome!' : 'Sad to see you go :`(';
  mailOptions.text = subscribed ? 'Thanks you for subscribing to our newsletter. You will receive our next weekly newsletter.' : 'I hereby confirm that I will stop sending you the newsletter.';

  return mailTransport.sendMail(mailOptions)
    .then(() => console.log(`New ${subscribed ? '' : 'un'}subscription confirmation email sent to:`, val.email))
    .catch((error) => console.error('There was an error while sending the email:', error));
});

Mi problema es que, después de implementar el código en la función firebase, la consola muestra que elsendEmailConfirmation no se puede ejecutar sin problemas debido aevent2.val no es una función.

Mi código actual combinado con mi código personalizado y el código original, quesendEmailConfirmation es el código original. Cuando ejecutó el código original de forma independiente, funcionó (el original eraevent en lugar deevent2 para la instantánea).

Por favor avise