CouchDB: The Definitive Guide

Chapter 14. Viewing Lists of Blog Posts

The last few chapters dealt with getting data into and out of CouchDB. You learned how to model your data into documents and retrieve it via the HTTP API. In this chapter, we’ll look at the views used to power Sofa’s index page, and the list function that renders those views as HTML or XML, depending on the client’s request.

Now that we’ve successfully created a blog post and rendered it as HTML, we’ll be building the front page where visitors will land when they’ve found your blog. This page will have a list of the 10 most recent blog posts, with titles and short summaries. The first step is to write the MapReduce query that constructs the index used by CouchDB at query time to find blog posts based on when they were written.

In Chapter 6, we noted that reduce isn’t needed for many common queries. For the index page, we’re only interested in an ordering of the posts by date, so we don’t need to use a reduce function, as the map function alone is enough to order the posts by date.

Map of Recent Blog Posts

You’re now ready to write the map function that builds a list of all blog posts. The goals for this view are simple: sort all blog posts by date.

Here is the source code for the view function. I’ll call out the important bits as we encounter them.

function(doc) {
  if (doc.type == "post") {

The first thing we do is ensure that the document we’re dealing with is a post. We don’t want comments or anything other than blog posts getting on the front page. ...