Unsubscribe link in emails sent

src/issue_delivery_worker.rs

@@ -44,13 +44,14 @@ pub async fn try_execute_task(
     if task.is_none() {
         return Ok(ExecutionOutcome::EmptyQueue);
     }
-    let (transaction, issue_id, email) = task.unwrap();
+    let (transaction, task) = task.unwrap();
     Span::current()
-        .record("newsletter_issue_id", display(issue_id))
-        .record("subscriber_email", display(&email));
-    match SubscriberEmail::parse(email.clone()) {
+        .record("newsletter_issue_id", display(task.newsletter_issue_id))
+        .record("subscriber_email", display(&task.subscriber_email));
+    match SubscriberEmail::parse(task.subscriber_email.clone()) {
         Ok(email) => {
-            let issue = get_issue(connection_pool, issue_id).await?;
+            let mut issue = get_issue(connection_pool, task.newsletter_issue_id).await?;
+            issue.inject_unsubscribe_token(&task.unsubscribe_token);
             if let Err(e) = email_client
                 .send_email(
                     &email,
@@ -73,7 +74,12 @@ pub async fn try_execute_task(
             );
         }
     }
-    delete_task(transaction, issue_id, &email).await?;
+    delete_task(
+        transaction,
+        task.newsletter_issue_id,
+        &task.subscriber_email,
+    )
+    .await?;
 
     Ok(ExecutionOutcome::TaskCompleted)
 }
@@ -84,6 +90,13 @@ struct NewsletterIssue {
     html_content: String,
 }
 
+impl NewsletterIssue {
+    fn inject_unsubscribe_token(&mut self, token: &str) {
+        self.text_content = self.text_content.replace("UNSUBSCRIBE_TOKEN", token);
+        self.html_content = self.html_content.replace("UNSUBSCRIBE_TOKEN", token);
+    }
+}
+
 #[tracing::instrument(skip_all)]
 async fn get_issue(
     connection_pool: &PgPool,
@@ -103,14 +116,20 @@ async fn get_issue(
     Ok(issue)
 }
 
+pub struct Task {
+    pub newsletter_issue_id: Uuid,
+    pub subscriber_email: String,
+    pub unsubscribe_token: String,
+}
+
 #[tracing::instrument(skip_all)]
 async fn dequeue_task(
     connection_pool: &PgPool,
-) -> Result<Option<(Transaction<'static, Postgres>, Uuid, String)>, anyhow::Error> {
+) -> Result<Option<(Transaction<'static, Postgres>, Task)>, anyhow::Error> {
     let mut transaction = connection_pool.begin().await?;
     let query = sqlx::query!(
         r#"
-        SELECT newsletter_issue_id, subscriber_email
+        SELECT newsletter_issue_id, subscriber_email, unsubscribe_token
         FROM issue_delivery_queue
         FOR UPDATE
         SKIP LOCKED
@@ -119,11 +138,12 @@ async fn dequeue_task(
     );
     let r = transaction.fetch_optional(query).await?;
     if let Some(row) = r {
-        Ok(Some((
-            transaction,
-            row.get("newsletter_issue_id"),
-            row.get("subscriber_email"),
-        )))
+        let task = Task {
+            newsletter_issue_id: row.get("newsletter_issue_id"),
+            subscriber_email: row.get("subscriber_email"),
+            unsubscribe_token: row.get("unsubscribe_token"),
+        };
+        Ok(Some((transaction, task)))
     } else {
         Ok(None)
     }

src/routes/admin/newsletters.rs

@@ -3,7 +3,7 @@ use crate::{
     idempotency::{IdempotencyKey, save_response, try_processing},
     routes::{AdminError, AppError},
     startup::AppState,
-    templates::MessageTemplate,
+    templates::{EmailTemplate, MessageTemplate, StandaloneEmailTemplate},
 };
 use anyhow::Context;
 use askama::Template;
@@ -27,8 +27,7 @@ pub struct BodyData {
 pub async fn insert_newsletter_issue(
     transaction: &mut Transaction<'static, Postgres>,
     title: &str,
-    text_content: &str,
-    html_content: &str,
+    email_template: &dyn EmailTemplate,
 ) -> Result<Uuid, sqlx::Error> {
     let newsletter_issue_id = Uuid::new_v4();
     let query = sqlx::query!(
@@ -40,8 +39,8 @@ pub async fn insert_newsletter_issue(
         "#,
         newsletter_issue_id,
         title,
-        text_content,
-        html_content
+        email_template.text(),
+        email_template.html(),
     );
     transaction.execute(query).await?;
     Ok(newsletter_issue_id)
@@ -56,9 +55,10 @@ pub async fn enqueue_delivery_tasks(
         r#"
         INSERT INTO issue_delivery_queue (
             newsletter_issue_id,
-            subscriber_email
+            subscriber_email,
+            unsubscribe_token
         )
-        SELECT $1, email
+        SELECT $1, email, unsubscribe_token
         FROM subscriptions
         WHERE status = 'confirmed'
         "#,
@@ -71,7 +71,9 @@ pub async fn enqueue_delivery_tasks(
 #[tracing::instrument(name = "Publishing a newsletter", skip(connection_pool, form))]
 pub async fn publish_newsletter(
     State(AppState {
-        connection_pool, ..
+        connection_pool,
+        base_url,
+        ..
     }): State<AppState>,
     Extension(AuthenticatedUser { user_id, .. }): Extension<AuthenticatedUser>,
     Form(form): Form<BodyData>,
@@ -90,7 +92,13 @@ pub async fn publish_newsletter(
         }
     };
 
-    let issue_id = insert_newsletter_issue(&mut transaction, &form.title, &form.text, &form.html)
+    let email_template = StandaloneEmailTemplate {
+        base_url: &base_url,
+        text_content: &form.text,
+        html_content: &form.html,
+    };
+
+    let issue_id = insert_newsletter_issue(&mut transaction, &form.title, &email_template)
         .await
         .context("Failed to store newsletter issue details.")?;
 

src/routes/admin/posts.rs

@@ -119,7 +119,5 @@ pub async fn create_newsletter(
         post_id,
         post_excerpt: "",
     };
-    let html_content = template.render().unwrap();
-    let text_content = template.text_version();
-    insert_newsletter_issue(transaction, post_title, &text_content, &html_content).await
+    insert_newsletter_issue(transaction, post_title, &template).await
 }

src/routes/unsubscribe.rs

@@ -1,4 +1,8 @@
-use crate::{routes::AppError, startup::AppState, templates::UnsubscribeTemplate};
+use crate::{
+    routes::AppError,
+    startup::AppState,
+    templates::{NotFoundTemplate, UnsubscribeTemplate},
+};
 use anyhow::Context;
 use askama::Template;
 use axum::{
@@ -29,7 +33,11 @@ pub async fn unsubscribe(
         .context("Could not update subscriptions table.")?;
 
     if result.rows_affected() == 0 {
-        Ok(StatusCode::NOT_FOUND.into_response())
+        Ok((
+            StatusCode::NOT_FOUND,
+            Html(NotFoundTemplate.render().unwrap()),
+        )
+            .into_response())
     } else {
         Ok(Html(UnsubscribeTemplate.render().unwrap()).into_response())
     }

src/templates.rs

@@ -63,8 +63,25 @@ pub struct NewPostEmailTemplate<'a> {
     pub post_excerpt: &'a str,
 }
 
-impl<'a> NewPostEmailTemplate<'a> {
-    pub fn text_version(&self) -> String {
+#[derive(Template)]
+#[template(path = "../templates/email/standalone.html")]
+pub struct StandaloneEmailTemplate<'a> {
+    pub base_url: &'a str,
+    pub html_content: &'a str,
+    pub text_content: &'a str,
+}
+
+pub trait EmailTemplate: Sync {
+    fn html(&self) -> String;
+    fn text(&self) -> String;
+}
+
+impl<'a> EmailTemplate for NewPostEmailTemplate<'a> {
+    fn html(&self) -> String {
+        self.render().unwrap()
+    }
+
+    fn text(&self) -> String {
         format!(
             r#"New post available!
 
@@ -86,10 +103,31 @@ Alphonse
 
 zero2prod - Building better backends with Rust
 Visit the blog: {}
-Unsubscribe: {}/unsubscribe
+Unsubscribe: {}/unsubscribe?token=UNSUBSCRIBE_TOKEN
 
 You're receiving this because you subscribed to the zero2prod newsletter."#,
             self.post_title, self.base_url, self.post_id, self.base_url, self.base_url,
         )
     }
 }
+
+impl<'a> EmailTemplate for StandaloneEmailTemplate<'a> {
+    fn html(&self) -> String {
+        self.render().unwrap()
+    }
+
+    fn text(&self) -> String {
+        format!(
+            r#"{}
+
+---
+
+zero2prod - Building better backends with Rust
+Visit the blog: {}
+Unsubscribe: {}/unsubscribe?token=UNSUBSCRIBE_TOKEN
+
+You're receiving this because you subscribed to the zero2prod newsletter."#,
+            self.text_content, self.base_url, self.base_url
+        )
+    }
+}