How to send emails that loop through arrays from firestore database - node.js

Question

I'm trying to send a user receipt from an eCommerce store. How do I loop through the data to send
I have tried using [] on the dynamic data.
import * as functions from "firebase-functions";
import * as admin from "firebase-admin";
admin.initializeApp();
const db = admin.firestore();
// Sendgrid Config
import * as sgMail from "#sendgrid/mail";
const API_KEY = functions.config().sendgrid.key;
const TEMPLATE_ID = functions.config().sendgrid.template;
sgMail.setApiKey(API_KEY);
//FUNCTIONS
export const newOrder = functions.firestore
.document("checkout/{checkoutId}/products/{productId}")
.onCreate(async (change, context) => {
// Read booking document
const postSnap = await db
.collection("checkout/{checkoutId}/products")
.doc(context.params.productId)
.get();
const booking = postSnap.data() || {};
//Email
const msg = {
to: "wilmutsami#gmail.com",
from: "test#example.com",
templateId: TEMPLATE_ID,
dynamic_template_data: {
subject: "Hey there, thank you for your order!",
name: booking.name,
amount: booking.amount
}
};
//Send it
return sgMail.send(msg);
});
Expected results are an email to the user displays a table of items that you ordered

Answer 1

If you want to get the data of the document that triggered the Cloud Function at checkout/{checkoutId}/products/{productId} you don't need to do
await db
.collection("checkout/{checkoutId}/products")
.doc(context.params.productId)
.get();
As explained in the doc:
When a function is triggered, it provides a snapshot of the data
related to the event. You can use this snapshot to read from or write
to the document that triggered the event, or use the Firebase Admin
SDK to access other parts of your database.
You can easily get the values of the document fields through the snap DocumentSnapshot as follows:
export const newOrder = functions.firestore
.document("checkout/{checkoutId}/products/{productId}")
.onCreate(async (snap, context) => {
const docData = snap.data();
const name = docData.name;
const amount = docData.amount;
// You can then use those values in the rest of your code
const msg = {
to: "wilmutsami#gmail.com",
from: "test#example.com",
templateId: TEMPLATE_ID,
dynamic_template_data: {
subject: "Hey there, thank you for your order!",
name: name,
amount: amount
}
};
return sgMail.send(msg);
});