How to provide a link to the 'next post'

Question

In a blog project that I'm playing with I have 'posts'. Here's the assemble block from my Gruntfile:

assemble: {
  options: {
    layout: ['src/layouts/default.hbs'],
    data: ['src/data/*.{json,yml}']
  },
  pages: {
    src: ['src/posts/**/*.md'],
    dest: 'tmp/posts/'
  }
}    

Each post is represented in markdown, with a dash of YFM, like so:

---
date: '20131129'
latitude: 7.113309999999999
longitude: -73.120468
city: Bucaramanga
country: Colombia


---

# A familiar face...

And then more blog content here...

Now, in my default.hbs, I have the standard things. I did a quick {{inspect page}} to see what variables I have handy. I can see in there, I have a few pieces of information that could be useful in this matter:

 "index": 46,
 "next": 47,
 "prev":45

I can think of a way to handle this by writing a custom handlebars helper, but it seems that given the presence of those variables, this functionality already exists somewhere... I'm just not finding it. The solution I have in mind seems disproportionately complex.

Thanks a bunch!

Answer 1

We recently added a pagination object to the context, but it only sorts on the source file name right now.

@jonschlinkert also created a helper that might be useful to you... https://github.com/helpers/handlebars-helper-paginate

We're doing a refactor of assemble right now and one thing we want to do is make it easier for these types of things to work without having to create custom helpers like this. I like your code though because it shows how to use underscore/lodash to sort pages by other properties.

Answer 2

I want to add this as "AN" answer, but hopefully not "THE" answer. Here is a handebars helper that I threw together in order to spit out a next path. This is the complete file with comments that probably make it look more intimidating than it is.

var _ = require('underscore');

var postPath = function(post){
  //pass a post object in, get back its path for linking
  var out = post['dest'].replace(/^tmp/, '');
  return out;
};

module.exports.register = function (Handlebars, options)  {
  Handlebars.registerHelper('nextPost', function (obj)  {
    var thisPage = obj['page']; // Created a local var for easier reading

    // The "this" object gets passed in as "obj" and contains an array of
    // pages. The trick is, this list isn't necessarily in order, even though
    // the folders are all named by date. Here I sort them. This seems rather
    // heavy handed, as the tax to process these increases exponentially with the
    // number of blog posts.
    // Also, I'm using underscore here to make the code much simpler.
    var sortedPages = _.sortBy(obj['pages'], function(page){ return page['data']['date']; });

    // Go through all of the sorted pages to find the matching data and get the index of where that is,
    // this way we can add one, to find the next element in the sorted array.
    var currentIndex = sortedPages.map(function(page) {return page['data']; }).indexOf(thisPage['data']);
    var nextIndex = currentIndex + 1;
    var out = '';

    // Don't wig out if it's the last one, just return a blank string instead.
    if (nextIndex > (sortedPages.length - 1)){
      out = '';
    }else{
      // Make a pretty path for use in our view
      out = postPath(sortedPages[nextIndex]);
    }
    return  out;
  });

};

A few of these lines can be taken out and put into their own methods for re-use for a "previousPost" helper method. But, something just stinks about this, and I would love it if someone could help me freshen it up, or point me in another direction.