Allow custom date formats

[sfahmy]

It seems the date formats for display are coded deep in the engine somewhere and not exposed through the templates or configuration files. It would be good to allow users to modify the date format.

[fhemberger]

Date formats are exposed to the templates, use the Liquid's date filter, e.g.

{{ post.date | date: "%Y-%m-%d" }}

List of format descriptors: http://liquid.rubyforge.org/classes/Liquid/StandardFilters.html#M000012

[sfahmy]

So is there a chance of getting date format added as a top-level preference? Otherwise, where in the template files must this be modified?

[sfahmy]

Looking through the source, the files all use _includes/post/date.html, but I see no such line in there? I think this being an option in the config file is useful, e.g. date_format: %d %M %Y in _config.yml, then all the template files can be updates so they use this. Otherwise, one must hack the template source, which isn't ideal.

[fhemberger]

Good point. I'll add a config flag for date …

[fhemberger]

I had a look at this issue again, unfortunately something like {{ date | date: "{{ site.date_format }}" }} isn't evaluated by Liquid and a filter (like ordinalize) doesn't know he's running in a Jekyll context, so I can't access the config variables at this point without ugly hacking.

[sfahmy]

Interesting. Which template files would need to be edited, and how? It could be added to the documentation, I suppose.

Why not let Jekyll/Ruby take care of the date format? It could be argued that the date format is something a site author would want to set regardless of the template used, so not using the Liquid filter isn't so bad.

[fhemberger]

You only need to modify _includes/post/date.html to adjust the date output.

Default date output in Ruby looks like this: 2011-10-18 12:30:46 +0200 ... not very pretty. Jekyll doesn't provide methods to format the output, it's only provided by Liquid (the template engine used). And that's the filter described above.

[sfahmy]

I was thinking more of Ruby's strftime method:
http://www.ruby-doc.org/core-1.9.2/Time.html#method-i-strftime

This could then be used in conjunction with a config variable.

[fhemberger]

Ok, I found a solution: I monkey patched Jekyll's to_liquid method to not just provide date but also date_formatted, which returns a strftime() formatted version of the date, which can be configured in _config.yml. I hope this will solve your issue, will commit it later.

[sfahmy]

Brilliant! Should make those of us not in the US happier with the date formats!

[sfahmy]

Turns out this works for blog posts, but not static pages. The time information in the tags is empty. Is it supposed to take care of formatting the updated date too?

[fhemberger]

It's only applied to posts so far, but I'll add it for pages, too (I need to override Jekyll's own methods for that).

In a later commit, I removed the support for "updated":

Jekyll does not support this value for Page or Post classes. The
capture returned an empty Sting, which was always evaluated to true
in '{% if updated %}'.

[sfahmy]

Does that mean that other commit mean we can no longer get last updated info displayed on pages? It was working previously.

[fhemberger]

@sfahmy Do you set the updated date manually in the YAML header of your post?
I only removed the flag, because it's not provided by Jekyll (e.g. in case you update your post). So I was wondering, where it came from ...

[sfahmy]

Correct, I set the updated to a date in the YAML header. That would result in the updated date being added at the bottom of pages. It's more useful for static pages than blog posts.

[sfahmy]

It looks like this is already somehow doable in Jekyll:
http://stackoverflow.com/questions/7395520/jekyll-date-format

[fhemberger]

Ah, ok. I'll add back support for updated and will commit the changes in the evening. I'm sorry, if this caused any inconvenience for you.

[fhemberger]

@sfahmy: Updated flag is back and custom dates work on pages, too.

[sfahmy]

Great, works perfectly!

Now I need to see how I might hack it so it ordinalizes even non standard date formats :) But that looks hard!

[fhemberger]

No, it's not. ;) I just added %o as ordinal representation of the day. Just use it in your date format string.

[sfahmy]

Fantastic! There's an error on line 39 though. It should read :
format.gsub!(/%o/, '%o')

The extra % messed things up, such that each page would have an increasing number of % signs prepending the date.

I just fixed it locally.

[fhemberger]

The second % was used as an escapement, but obviously this is not needed in Ruby. You can remove the line altogether.