Using the WordPress API to create a newsletter from your posts

In this tutorial, we'll learn how to fetch content from an API, process it, and display it in an HTML email newsletter with Maizzle.

You can preview the final result on CodePen.

Initial setup

As always, make sure you have Maizzle CLI installed.

Next, open a CLI and run the new command to scaffold a new project:

maizzle new

Follow the steps, using example-wordpress as the folder name.

Once it finishes installing dependencies, open the project in your favorite editor.

WordPress API

Instead of imagining abstract APIs and how you'd interact with them, let's work with a real one so you can actually follow along and test things out yourself.

Given its popularity, we'll be using the WordPress REST API in our example. We'll also need to fetch data from a real blog, so let's use the wonderful CSS-Tricks.

The WordPress API on CSS-Tricks is available at https://css-tricks.com/wp-json/wp/v2/

Click that link and you'll see the various routes you can access.

/posts route

We can fetch posts from the /posts route:

https://css-tricks.com/wp-json/wp/v2/posts/

We can also use query string parameters in order to refine our API call.

For example, this only asks for the 3 latest posts:

https://css-tricks.com/wp-json/wp/v2/posts?page=1&per_page=3&_embed=1

Fetch posts

Let's use the <fetch> tag to fetch posts from the CSS-Tricks WordPress API. 

<fetch url="https://css-tricks.com/wp-json/wp/v2/posts?page=1&per_page=6&_embed=1">
  <!-- Posts are now available in {{ response }} -->
</fetch>

Use in Template

promotional.html in Maizzle displays 6 articles in four different layouts. Above, we're also fetching the latest 6 articles from CSS-Tricks, so it's a perfect fit 🙄

Featured Post

Let's update the Hero with background image to show the first post.

Our code becomes:

---
bodyClass: bg-gray-200
title: "Latest posts on CSS-Tricks"
preheader: "👀 Lorem, ipsum, and much dolor in this week's edition"
---

<fetch url="https://css-tricks.com/wp-json/wp/v2/posts?page=1&per_page=6&_embed=1">
  <!-- ... existing template markup before the HERO <tr> -->
  <tr>
    <td class="bg-top bg-no-repeat bg-cover rounded text-left" style="background-image: url('{{ response[0]._embedded['wp:featuredmedia'][0]['source_url'] || 'https://via.placeholder.com/600x400' }}');">
      <!--[if mso]>
      <v:image src="{{ response[0]._embedded['wp:featuredmedia'][0]['source_url'] || 'https://via.placeholder.com/600x400' }}" xmlns:v="urn:schemas-microsoft-com:vml" style="width:600px;height:400px;" />
      <v:rect fill="false" stroke="false" style="position:absolute;width:600px;height:400px;">
      <v:textbox inset="0,0,0,0"><div><![endif]-->
      <div class="leading-32">&zwnj;</div>
      <table class="w-full">
        <tr>
          <td class="w-48 sm:w-16"></td>
          <td>
            <h1 class="m-0 mb-16 text-4xl text-white sm:leading-40">{{ response[0].title.rendered }}</h1>
            <div class="m-0 text-white text-lg leading-24">{{ response[0].excerpt.rendered }}</div>
            <div class="leading-32">&zwnj;</div>
            <table>
              <tr>
                <th class="bg-indigo-800 hover:bg-indigo-700 rounded" style="mso-padding-alt: 16px 24px;">
                  <a href="{{ response[0].link }}" class="block font-semibold text-white text-base leading-full py-16 px-24 no-underline">Read more &rarr;</a>
                </th>
              </tr>
            </table>
          </td>
          <td class="w-48 sm:w-16"></td>
        </tr>
      </table>
      <div class="leading-32">&zwnj;</div>
      <!--[if mso]></div></v:textbox></v:rect><![endif]-->
    </td>
  </tr>
</fetch>

We can use response[index] to output data for each post, manually. For example, we would use response[1].title.rendered to show the title of the second post.

Post dates

We can add a function to config.js and use it to format the post's date according to our audience's locale:

// config.js
module.exports = {
  formattedDate: (str) => {
    const date = new Date(str)
    return date.toLocaleDateString('en-US', {day: 'numeric', month: 'short', year: 'numeric'})
  }
}

We can then display it in the template with Nunjucks, like so:

{{ page.formattedDate(response[1].date) }}

Looping

We can use the <each> tag in Maizzle to loop over each item in the response:

<fetch url="https://css-tricks.com/wp-json/wp/v2/posts?page=1&per_page=6&_embed=1">
  <each loop="post in response">
    {{ post.title.rendered }}
  </each>
</fetch>

Want to loop over a specific subset only? You can use expressions when creating the loop.

For example, let's show the last 2 posts in a list format at the end of the template:

<fetch url="https://css-tricks.com/wp-json/wp/v2/posts?page=1&per_page=6&_embed=1">
  <h3 class="m-0 text-base font-semibold text-gray-500 uppercase">From the archives</h3>
  <div class="leading-24">&zwnj;</div>
  <table class="w-full">
    <each loop="post in response.slice(-2)">
      <tr>
        <td>
          <p class="text-xs text-gray-500 mb-2">{{ page.formattedDate(post.date) }}</p>
          <h4 class="m-0 mb-4 text-xl font-semibold">
            <a href="{{ post.link }}" class="text-blue-500 hover:text-blue-400 no-underline">{{ post.title.rendered }}</a>
          </h4>
          <div class="m-0 text-gray-500">{{ post.excerpt.rendered }}</div>
          <if condition="loop.last">
            <table class="w-full">
              <tr>
                <td class="py-24">
                  <div class="bg-gray-300 h-px leading-px">&zwnj;</div>
                </td>
              </tr>
            </table>            
          </if>
        </td>
      </tr>
    </each>
  </table>
</fetch>

Notes:

  • we also added the post date in a paragraph above the title
  • we're using the loop metadata to output the divider only between list items

Conclusion

All that we've done in this tutorial is to:

  1. Use the <fetch> tag to fetch JSON data from an API endpoint
  2. Use that data in a Maizzle template

So this isn't tied to WordPress: it was used as an example because of its convenient API, but you're free to implement it with any other APIs.

Some ideas:

  • use your CMS as an authoring system for your newsletter's content
  • show the latest products from your store
  • include data from public APIs

Resources