Permit default_title, default_content, and default_excerpt filters to work as expected

[mnelson4]

Description

Don't assume new posts have only blank content. They may have defaults set using the filters default_content, default_title and default_excerpt

How has this been tested?

Add this code snippet to functions.php:

add_filter( 'default_title', function() {
	return 'My default title';
} );

add_filter( 'default_content', function() {
	return 'My default content';
} );

add_filter( 'default_excerpt', function() {
	return 'My default excerpt';
} );

when you create a new post with the classic editor, those default values will appear immediately when you begin a new post.
However, when you create a new post in Gutenberg, those default values don't appear.

Screenshots

Classic editor:

Gutenberg Master:

Gutenberg this branch:

Types of changes

Bug fix. Addresses #8757 (comment)
All we needed to do is not ignore the values already set on the global $post.

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.

[tofumatt]

Interesting! This makes sense but I'm not really familiar enough with the filter-world to review this. Flagging the core team for a review.

[aduth]

I've yet to test this, but I expect without the default_title filter present, the new post will show with a "Auto-Draft" title ?

[danielbachhuber]

For the record, it looks like the original source of apply_filters( 'the_title' ) was #1967 a2ffbd2#diff-620130744b6b73b822a3df609671d930R548

It'd be great to have e2e tests around this too.

[mnelson4]

I've yet to test this, but I expect without the default_title filter present, the new post will show with a "Auto-Draft" title ?

From my testing, that doesn't happen. On this branch, without adding those filter callbacks to functions.php, the UX is the same as master.
Here's a video that should help. At first, I show the code snippet is active, and the Gutenberg editor gets pre-populated with the default values specified in those callbacks. Then I commented out those code snippets, and began adding a new post with Gutenberg, and the title, body, and excerpt all began as blank, as expected. See https://drive.google.com/file/d/1v9Ff3JLAtAfDhFhU8yyMs8TmAXoaks6n/view

So: the title "Auto-Draft" doesn't appear in the post editor. (I believe that's because the auto-draft that's created gets that title, but that's different from the $post object used to populate the post-new.php form; and when the auto-draft is update via a REST API call later, its post_title gets updated to be whatever is currently in the title field in the editor.)

It'd be great to have e2e tests around this too.

I have yet to write any end-to-end tests but am happy for an opportunity! I'll see what I can do...

[mnelson4]

oh also I see the title's raw value was originally set to apply_filters( 'the_title', '', $post->ID ), on cd6ae73755 for the reason @aduth mentioned, but like I said from my testing that's isn't currently the case. (Maybe it was at the time?)

Also, it was strange that we were applying the filter on the raw value. Elsewhere we apply that filter to the rendered value

[Chouby]

The "auto-draft" title is coming from the REST API, used there: https://github.com/WordPress/gutenberg/blob/master/lib/client-assets.php#L1305

By default, for a new post, the global $post (and the corresponding post in database) has an empty title.
The purpose of the $initial_edits array is to overwrite the values coming from the REST API. That's why the title is already filled with an empty value before applying this PR, just to avoid "auto-draft" to be displayed.
Since the PR still always overwrites the title coming from the REST API, there is no risk see the "auto-draft' title.

It also looks strange to me to apply the filter 'the_title' here.

[mnelson4]

I added another test file and a supporting plugin. I also considered adding the test as part of new-post.test.js. Let me know if that would be better.

I'm new to Puppeteer and Jest, so had difficulty selecting the excerpt in order to assert it also got changed. I left the code commented out, hoping someone could help me figure that part out.

Otherwise, I think this is pretty helpful, I think.

[mnelson4]

Ok now the tests are asserting the excerpt is correct too.

So I believe this is ready for a review.

[danielbachhuber]

Thanks @mnelson4 !

Could you add one more e2e test (if there isn't one already) asserting that the default state of title is empty when creating a new post without your custom plugin active?

[mnelson4]

Could you add one more e2e test (if there isn't one already) asserting that the default state of title is empty when creating a new post without your custom plugin active?

I added an assertion to the already existing new-post.test.js's test 'should show the New Post page in Gutenberg'. It seemed to me those tests are meant to assert the new editor's default state, and this seems to be part of it. (And I'm still open to adding my new test to that existing file instead of a new file)

[danielbachhuber]

💯 Thanks for your work on this, @mnelson4

[tmatsuur]

Great. I am looking forward to the next version.