Val Town email subscriptions: send email newsletter
Cousin Val to @petermillspaugh/emailSubscription — see docs there.
This Val has a few layers of protection to avoid double sending. Those mechanisms feel pretty hacky, so any suggestions are welcome! Feel free to comment on the Val or submit a PR.
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/** @jsxImportSource https://esm.sh/preact */
import { generateNewsletterJsx } from "https://esm.town/v/petermillspaugh/generateNewsletterJsx";
import { newsletters } from "https://esm.town/v/petermillspaugh/newsletters";
import { email as sendEmail } from "https://esm.town/v/std/email?v=11";
import { sqlite } from "https://esm.town/v/std/sqlite?v=4";
import { render } from "npm:preact-render-to-string";
type SubscriberRow = [
subscriberId: number,
emailAddress: string,
];
export async function sendEmailNewsletter(interval: Interval) {
const { jsx: newsletterContent, subject, webUrl, targetSendDate } = newsletters[newsletters.length - 1];
// no-op and alert if the current timestamp isn't within five minutes of the targetSendDate
const fiveMinutes = 5 * 60 * 1000;
if (Math.abs(new Date(targetSendDate).getTime() - Date.now()) > fiveMinutes) {
return await sendEmail({
subject: "Alert! Unexpected error in sendEmailNewsletter",
html: `Send attempt for newsletter_id=${newsletters.length} is not within 5 minutes of target send date`,
});
}
// no-op and alert if interval was run <28 days ago (enforce max one newsletter per month)
const twentyEightDaysAgo = Date.now() - (28 * 24 * 60 * 60 * 1000);
if (!interval.lastRunAt || interval.lastRunAt.getTime() > twentyEightDaysAgo) {
return await sendEmail({
subject: "Alert! Unexpected error in sendEmailNewsletter",
html: "Val fired twice in <28 days",
});
}
const { rows: newsletterEmailLogs } = await sqlite.execute({
sql: `SELECT * FROM email_logs WHERE newsletter_id = ?;`,
args: [newsletters.length],
});
// no-op and alert if there's already a log of the latest newsletter
if (newsletterEmailLogs.length > 0) {
return await sendEmail({
subject: "Alert! Unexpected error in sendEmailNewsletter",
html: `Duplicate send attempt for newsletter_id=${newsletters.length}`,
});
}
const { rows: subscribers } = await sqlite.execute(
`
SELECT id, email
FROM subscribers
WHERE verified = 1
AND subscribed_at IS NOT NULL;
`,
);
for (const [subscriberId, emailAddress] of subscribers as unknown as SubscriberRow[]) {
const { rows: subscriberEmailLogs } = await sqlite.execute({
sql: `
SELECT *
FROM email_logs
WHERE newsletter_id = ?
AND subscriber_id = ?;
`,
args: [newsletters.length, subscriberId],
});
// skip subscriber and alert if log exists for newsletter + subscriber
if (subscriberEmailLogs.length > 0) {
await sendEmail({
subject: "Alert! Unexpected error in sendEmailNewsletter",
html: `Duplicate send attempt for subscriber_id=${subscriberId} and newsletter_id=${newsletters.length}`,
});
continue;
}
const jsx = generateNewsletterJsx({ webUrl, newsletterContent, emailAddress });
await sendEmail({
subject,
html: render(jsx),
to: emailAddress,
from: {
name: "Pete Millspaugh",
email: "petermillspaugh.sendEmailNewsletter@valtown.email",
},
replyTo: "pete@petemillspaugh.com",
});
// log sent email
await sqlite.execute({
sql: `
INSERT INTO email_logs (newsletter_id, subscriber_id)
VALUES (?, ?);
`,
args: [newsletters.length, subscriberId],
});
}
}
Val Town email subscriptions: newsletter reminder
Cousin Val to @petermillspaugh/emailSubscription for emailing yourself a reminder to send your next newsletter.
Since this Val is public, anyone can run it. I've commented out the function body that actually emails me to prevent anyone from spamming me, but you can fork this as a private Val to set a cron reminder.
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import { newsletters } from "https://esm.town/v/petermillspaugh/newsletters";
import { email } from "https://esm.town/v/std/email?v=11";
export async function sendNewsletterReminder(interval: Interval) {
// await email({
// subject: `Reminder to prepare newsletter #${newsletters.length + 1}`,
// html: `One week left to write up the next newsletter!`,
// });
}