Adds updated_diff option to post_meta

[SafeEval]

When post_meta.updated_at is enabled, all posts show a modification date,
even when it is the same as the creation date. The post_meta.updated_diff
flag only displays the modification date if it is different than the
creation date.

PR Type

What kind of change does this PR introduce?

• Bugfix.
• Feature.
• Code style update (formatting, local variables).
• Refactoring (no functional changes, no api changes).
• Build related changes.
• CI related changes.
• Documentation content changes.
• Other... Please describe:

What is the current behavior?

When post_meta.updated_at is enabled, posts will always show a modification date, even when it is the same as the creation date.

Example:

# _config.yml

post_meta:
  created_at: true
  updated_at: true

Result:

Posted on 2018-01-18 | Post modified: 2018-01-18

What is the new behavior?

If both updated_at and updated_diff are true, then the modified date will only be displayed if different from the creation date.

If updated_diff is false (default), then behavior is unchanged.

How to use?

In NexT _config.yml:

post_meta:
  created_at: true
  updated_at: true
  updated_diff: true

---

In a post's meta data:

date: 2018-01-18
updated: 2018-01-18

Result:

Posted on 2018-01-18

---

In a post's meta data:

date: 2018-01-18
updated: 2018-01-19

Result:

Posted on 2018-01-18 | Post modified: 2018-01-19

Does this PR introduce a breaking change?

• Yes.
• No.

[tsanie]

It will cause problems when the user choose only to show the updated_at and not the created_at.

[SafeEval]

You're right, thanks. Just revised and verified expected behavior with created_at, updated_at, and updated_diff, by themselves and together.

[tsanie]

Good jobs, I'd like this feature. 👍

But I think here {% if display_updated %} should be {% if theme.post_meta.updated_at && (display_updated || !theme.post_meta.created_at) %}, otherwise any datetime would not be shown when the article's created time equals its updated time and the created_at == false and updated_at == true and updated_diff == true

PS: this config is not normalize but I think it could be a situation. (on the test-case? 😃)

[ivan-nginx]

theme.post_meta

# Post meta display settings
post_meta:
  item_text: true
  created_at: true
  updated_at: false
  categories: true

This is default configuration.

[ivan-nginx]

Must be:

1. If there is created and updated equal, then show only created.
2. If there is created and updated not equal, show as it:
   2.1. If updated section in config enabled, then show created & updated.
   2.2. If not enabled, show only created.

[SafeEval]

@tsanie: It's good to be thorough and cover all possible configurations. Now it only displays the updated datetime when created_at: false and updated_at: true, for both equal and unequal created/updated datetimes.

@ivan-nginx: correct, that is how it works, plus a couple additional cases.

All 8 possible cases have been verified to work as expected. When update_diff: true, then:

1. If date: 2018-01-01, updated: 2018-01-01 (equal):
   1.1. If created_at: true, updated_at: true, then result:

   Posted on 2018-01-01

   1.2. If created_at: true and updated_at: false, then:

   Posted on 2018-01-01

   1.3. If created_at: false and updated_at: true, (pointed out by @tsanie) then:

   Post modified: 2018-01-02

   1.4. If created_at: false and updated_at: false, then:

   Nothing

2. If date: 2018-01-01, updated: 2018-01-02 (unequal):
   2.1. If created_at: true and updated_at: true, then:

   Posted on 2018-01-01 | Post modified: 2018-01-02

   2.2. If created_at: true and updated_at: false, then:

   Posted on 2018-01-01

   2.3. If created_at: false and updated_at: true, (pointed out by @tsanie) then:

   Post modified: 2018-01-02

   2.4. If created_at: false and updated_at: false, then:

   Nothing

[ivan-nginx]

@HuntedCodes how u not brake your brain with this cases? 😃
So, all tested, worked and can be merged?

[ivan-nginx]

One excess space before date_updated_diff string here.

[SafeEval]

Fixed the whitespace, and everything was tested.

[SafeEval]

@ivan-nginx a lot of coffee, and good sleep 😴😴😴😴 ☕️ ☕️ ☕️ ☕️

[ivan-nginx]

Well, at the end of this day i think need a little beer. 🍺 😈

[SafeEval]

Beer is for merge conflicts lol

[ivan-nginx]

Sometimes it bring fresh ideas and give another point of view on different things.
But sometimes give a little angry or misunderstanding, yes.