How to use SendGrid API with Dynamic Templates with NodeJS

Question

I have a dynamic template in SendGrid, s.t. using Postman with a POST request to https://api.sendgrid.com/v3/mail/send

with the following json:

{
    "personalizations": [{
        "to": [{
            "email": "dariusgoore@gmail.com",
            "name": "test"
        }],
        "dynamic_template_data":{
            "name":"John",
            "text": "Someone just added a new post!",
        }
    }],
    "from": {
        "email": "team@writerboards.com",
        "name": "test"
    },
    "reply_to": {
        "email": "dariusgoore@gmail.com",
        "name": "test"
    },
    "template_id": "d-c8f201dd360d40bc877da13a1a0b36b1"
}

works to send an email using the template.

However, I can't seem to send an analogous request from Express.

Here is my route that calls SendGrid (end point responds to a cron job):

const express = require('express');
const User = require('../models/User');
const Act = require('../models/Act');
const sgMail = require('@sendgrid/mail');
sgMail.setApiKey(process.env.SENDGRID_API_KEY);

let router = express.Router();

router.get('/', async (req, res) => { 
  // getdate 14 days ago
  var ago_date = new Date();
  ago_date.setDate(ago_date.getDate()-0)
  // loop through users
  console.log('crons: getting users');
  const users = await User.query();
  console.log('crons:  number of users: ', users.length);
  for (const user of users) {

console.log(user.username)
const lastAct = await Act
  .query()
  .where('users_id', user.id)
  .orderBy('created_at', 'desc')
  .limit(1);

  const msg = {
    to: 'dariusgoore@gmail.com',
    from: 'team@writerboards.com',
    templateId: 'd-c8f201dd360d40bc877da13a1a0b36b1',

    dynamic_template_data: {
      subject: 'Testing Templates',
      name: 'Some One',
      text: 'Denver',
    },
  };

  console.log('this is the msg 2b sent: ', msg)
  const {
    classes: {
      Mail,
    },
  } = require('@sendgrid/helpers');
  const mail = Mail.create(msg);
  const body = mail.toJSON();
  console.log('this is the body: ', body);
  await sgMail.send(msg); 

  res.json({
    success: true, message: 'ok'
  });   // respond back to request
// };
  };

  res.json({
    success: true, message: 'ok' 
  }); 
});

here is the error trace showing an error:

Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client:

Full trace below:

userone
sending email re on post
this is the msg 2b sent:  { to: 'dariusgoore@gmail.com',
  from: 'team@writerboards.com',
  templateId: 'd-c8f201dd360d40bc877da13a1a0b36b1',
  dynamic_template_data:
   { subject: 'Testing Templates',
     name: 'Some One',
     text: 'Denver' } }
this is the body:  { from: EmailAddress { email: 'team@writerboards.com', name: '' },
  subject: undefined,
  personalizations: [ { to: [Array], dynamic_template_data: [Object] } ],
  template_id: 'd-c8f201dd360d40bc877da13a1a0b36b1' }
usertwo
sending email re on post
this is the msg 2b sent:  { to: 'dariusgoore@gmail.com',
  from: 'team@writerboards.com',
  templateId: 'd-c8f201dd360d40bc877da13a1a0b36b1',
  dynamic_template_data:
   { subject: 'Testing Templates',
     name: 'Some One',
     text: 'Denver' } }
this is the body:  { from: EmailAddress { email: 'team@writerboards.com', name: '' },
  subject: undefined,
  personalizations: [ { to: [Array], dynamic_template_data: [Object] } ],
  template_id: 'd-c8f201dd360d40bc877da13a1a0b36b1' }
(node:19822) UnhandledPromiseRejectionWarning: Error [ERR_HTTP_HEADERS_SENT]: Cannot set headers after they are sent to the client
    at ServerResponse.setHeader (_http_outgoing.js:470:11)
    at ServerResponse.header (/Users/dariusgoore/development/writerboard/writerboard-express-api/node_modules/express/lib/response.js:771:10)
    at ServerResponse.send (/Users/dariusgoore/development/writerboard/writerboard-express-api/node_modules/express/lib/response.js:170:12)
    at ServerResponse.json (/Users/dariusgoore/development/writerboard/writerboard-express-api/node_modules/express/lib/response.js:267:15)
    at router.get (/Users/dariusgoore/development/writerboard/writerboard-express-api/src/routes/crons.js:54:11)
    at process._tickCallback (internal/process/next_tick.js:68:7)
(node:19822) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 3)

If you know the solution why you cannot put it as an answer? — Sampath, Jul 22 '20 at 21:11
Hi @user2799827 can you send me the solution to this problem? Thanks! — Angelina Tsuboi, Jul 24 '20 at 15:54

score 13 · Answer 1 · edited May 05 '23 at 05:40

Apologies for the years late response.

We actually reworked our entire backend, and tbh, I have no memory of exactly what we did.

Anyway, here is the code of the working route:

const express = require('express');
const axios = require('axios');
const Analytics = require('analytics-node');
const client = new Analytics('write key');

const auth = require('../middlewares/authenticate');

const User = require('../models/User');
const Post = require('../models/Post');
const Group = require('../models/Group');

// SendGrid initialization
const sgMail = require('@sendgrid/mail');
sgMail.setApiKey(process.env.SENDGRID_API_KEY);

let router = express.Router();

router.post('/', auth.required, async (req, res, next) => {
    await Post.query().insert({
        body: req.body.post.body,
        users_id: req.user.id,
        groups_id: req.body.post.groupId,
        parents_id: req.body.post.parents_id
    });

    let poster = await User.query().findById(req.user.id)
    let group = await Group.query()
        .findById(req.body.post.groupId)
        .eager('user');

    client.track({
        event: 'Post created',
        userId: req.user.id,
        properties: {
            body: req.body.post.body
        }
    });

    let newPost = req.body;
    let recipients = group.user.filter(el => (
        el.id !== poster.id 
    ));

    // Check to see if the environment is in production before sending the email.
    if(process.env.NODE_ENV !== "production") return res.json({
        success: false, 
        message: "fail" 
    });

    for(let i = 0; i < recipients.length; i++){
        sgMail.send({
            from: "email@domain.com",
            template_id: process.env.SENDGRID_NEW_POST,
            asm: {
                // new post notification list
                groupId: 20914 
            },
            personalizations: [{
                to: { email: recipients[i].email },
                dynamic_template_data: {
                    subject: `New Post: ${poster.username} just posted something`,
                    recipient_name: recipients[i].username, 
                    poster_name: poster.username,
                    group_name: group.name,
                    post_text: newPost.post.body,
                    button_url: process.env.VUE_HOME_URL,
                },
            }]
        });
    }

    res.json({ success: true, message: "ok" });
});

score 0 · Answer 2 · answered Mar 21 '20 at 09:19

0

Sorry for late response but I think the main issue here is that you are sending 2 responses at the end of your function and on the second time, express tells you that you have already sent a response by throwing an exception.

Not sure if the sendgrid part of the code is right, I was actually searching for more documentation on the dynamic template API.

answered Mar 21 '20 at 09:19

ulyssimus

1
3

thanks for the response. I actually did get this working. shoot me a dm if you want details. – user2799827 Mar 21 '20 at 10:18
@user2799827, it's totally acceptable to answer your own question if you have the answer to give – uɥƃnɐʌuop Dec 03 '20 at 21:13

How to use SendGrid API with Dynamic Templates with NodeJS

2 Answers2