Adding Next and Previous Links

Sometimes it's desirable to provide links to the "next" and "previous" piece on the "show page" for that piece (the show.html template).

To enable that, just configure your module that subclasses apostrophe-pieces-pages appropriately:

// lib/modules/my-articles-pages/index.js
module.exports = {
  extend: 'apostrophe-pieces-pages',
  next: true,
  previous: true
  // other options, etc.
};

NOTE

Here we'e assuming that my-articles extends apostrophe-pieces directly, and my-articles-pages extends apostrophe-pieces-pages, but you can also do this trick with modules that extend apostrophe-blog-pages, apostrophe-events-pages and other existing subclasses.

Turning on these options causes Apostrophe to load the next and previous documents into data.previous and data.next, so you can output links like this, often at the bottom of show.html:

{# lib/modules/my-articles-pages/views/show.html #}
{% if data.previous %}
  <h4>
    <a href="{{ data.previous._url }}">Back to {{ data.previous.title }}</a>
  </h4>
{% endif %}

{% if data.next %}
  <h4>
    <a href="{{ data.next._url }}">Next: {{ data.next.title }}</a>
  </h4>
{% endif %}

By default you can access any property of data.previous or data.next. For better performance, you may want to limit them with a projection, much as you would for a join:

// lib/modules/my-articles-pages/index.js
module.exports = {
  extend: 'apostrophe-pieces-pages',
  previous: {
    projection: {
      title: 1,
      slug: 1,
      tags: 1,
      type: 1
    }
  },
  next: {
    projection: {
      title: 1,
      slug: 1,
      tags: 1,
      type: 1
    }
  }
  // other options, etc.
};

TIP

These are the minimum fields recommended. Except for title, all of them play a role in building the dynamic _url property correctly.

"Next", "previous" and blog posts

One thing that might be confusing: for this purpose, "next" means "appears next in the list of pieces in the index.html view." and "previous" means "appears previously in the list of pieces in the index.html view."

For most types of pieces, this is intuitive. But since blogs are displayed in reverse chronological order, there it can seem a little backwards. So just keep in mind that you may need to use different language for your links on the front end.

Fetching the next or previous piece programmatically

This feature is implemented using the next and previous cursor filter methods. You can use those yourself:

// `doc` is a piece we already fetched
return self.find(req).previous(doc).toObject(function(err, previous) { ... });

The same technique can be used with next.