Add sort_by to sort posts/pages

[haacked]

Related to #1735

Proposed syntax:

{% for group in site.pages.sort_by(:someProperty, 'asc') %}
   <h2>{{ group.Name }}</h2>
   <ul>
   {% for item in group.Items %}
      <li>{{ item.FooBar }}</li>
    {% endfor %}
  </ul>
{% endfor %}

If you don't specify 'asc' or 'desc' then it should probably do it 'desc' by default?

Also, I found a proposed :order keyword here: http://stackoverflow.com/questions/9218769/order-an-array-with-jekyll-liquid-template

Seems to me that chaining methods makes more sense to be consistent with the other operations, but I don't feel too strongly either way.

One thing to consider is multiple sorts:

site.pages.sort_by(:someProperty, 'asc').then_by(:anotherProperty, 'desc');

But I leave it to you to sort out the rubyisms. (pun intended).

[parkr]

I think it'd be smarter to write the sort_by filter such that it just sorts, and people can use the group_by (#1788) filter to group things. So to achieve what you want above, it'd look something like this:

{% for group in site.pages | group_by: "category" | sort_by: "name" %}
   <h2>{{ group.name }}</h2>
   <ul>
   {% for page in group.items %}
      <li>{{ page.title }}</li>
    {% endfor %}
  </ul>
{% endfor %}

[haacked]

How would you sort by category, then date, then author?

[nikmd23]

It'd be great to be able to pick the property to sort on for a "complex object".

An example, taken from the ossPerks.com front-matter, which sorts on a perk's name:

{% for item in page.perks | sort_by: "perk.name" %}
    {% include perk.html %}
{% endfor %}

Another alternative (not as nice) would be to annotate the property to sort on in the YAML:

perks:
- perk: {name: !!sort Crowdin, uri: 'http://crowdin.net/pricing'}
  description: Translation and localization management platform that handles both documents and software projects.
  categories: [Translation, Localization]
  company: {name: Crowdin, uri: 'http://crowdin.net/'}

- perk: {name: !!sort SSL Certificate, uri: 'http://www.godaddy.com/ssl/ssl-open-source.aspx'}
  description: One year free SSL Certificate from GoDaddy.
  categories: [TLS, SSL, Infrastructure]
  company: {name: GoDaddy, uri: 'http://www.godaddy.com/'}

which would simplify the syntax used in the for statement:

{% for item in page.perks | sort_by: "perk" %}
    {% include perk.html %}
{% endfor %}

[nikmd23]

I agree with @haacked that multi-level sorting is important, but I don't care much about the syntax to make it work.

[parkr]

@haacked Does the Liquid sort tag work for this?

sort (input, property = nil)

Sort elements of the array provide optional property with which to sort an array of hashes or drops.

Example:

{% assign variants = product.variants | sort: 'price' %}
{% for variant in variants %}

{{ variant.title }} - {{ variant.price | money }}

{% endfor %}

From: http://docs.shopify.com/themes/liquid-basics/output#manipulation

[haacked]

Interesting. I don't see any way to specify 'ascending' or 'descending'.

[parkr]

@haacked Right, because they also have the reverse filter :)

{{ my_array | sort | reverse }}

[haacked]

Ahh! Ok, I'll close this. :)

[afeld]

Does the Liquid sort tag work for this?

Note that you can only sort site.pages by the attributes listed here. Less than ideal 😐

[haacked]

Oh snap! That is very limiting. I should be able to sort by any property of page including custom fields. So is this an issue for liquid then?

[afeld]

I'll take a crack at it.

[parkr]

@afeld: This should help: #1829