Introduce exclusion for WP_Theme::scandir()

[lukasbesch]

I am using NPM to manage my theme's dependencies during development and ran into the following issue where accessing wp-admin/edit.php?post_type=page returned an empty response. Tracing it down I found out that WordPress is looking for possible page templates in the theme directory. Scanning the node_modules folder is probably too much a server can handle.

To solve this problem I suggest to introduce an exclusion list so theme developers can add directories (and files) that will be ignored when searching for post templates. I am not aware of any disadvantages of this solution and don't exactly know where the function is used elsewhere.

[lukasbesch]

Proposed fix

[dd32]

given the line before it is if ( '.' == $result[0] ) continue; which is mostly used to skip .svn folders, and there's a CVS check within the next block, it's probably worth just hard-coding node_modules into the code here to skip for everyone (given how common it is to use a node-based development method today).

To make it more readable we can define those skip-directories as an array that's filtered if it makes it more readable.

[lukasbesch]

There shouldn't be a reason to scan node_modules, so we should be safe to hardcode. But let's keep it filterable yet so one can add other package managers or libraries to that array.

[swissspidy]

@lukasbesch Thanks for your patch! Would you mind adding documentation according to the inline docs standards? See ​https://make.wordpress.org/core/handbook/best-practices/inline-documentation-standards/php/. Also, braces for conditions are a requirement for newly added code as per our coding standards.

[lukasbesch]

Added documentation and exclude node_modules and CVS by default

[ryelle]

I was also having this problem, and the patch fixes it 👍

[norcross]

good work @lukasbesch I ran into this issue myself and this patch solved the problem.

[Faison]

Thanks @lukasbesch , I just learned that this issue is making my local WP REST API requests pretty slow. With your patch I'm saving nearly half a second in my response time :D

[rachelbaker]

Seems like more and more folks are running into this issue as they create REST API powered themes. We should fix this in the next minor release.

[swissspidy]

The in_array() check in the current patch should be a strict check.

[rachelbaker]

Added strict check & since tag and adjusted spacing.

[rachelbaker]

In 38292.3.diff​ I made some minor code style adjustments, added the @since tag to the filter documentation, and used a strict in_array() check. @swissspidy can you look this over to make sure I didn't miss anything?

[rachelbaker]

In 40301:

Themes: Add filter for excluding directories from being scanned for template files.

Exclude 'node_modules' directories from paths searched in WP_Theme::scandir(). Introduces the theme_scandir_exclusions filter to allow sites to exclude any other paths like bower_components or vendor from being searched for template files.

Props lukasbesch, dd32, swisspidy, rachelbaker.
Fixes #38292.

[rachelbaker]

Reopening for porting to the 4.7.4 branch.

[swissspidy]

In 40326:

Themes: Add filter for excluding directories from being scanned for template files.

Exclude 'node_modules' directories from paths searched in WP_Theme::scandir(). Introduces the theme_scandir_exclusions filter to allow sites to
exclude any other paths like bower_components or vendor from being searched for template files.

Props lukasbesch, dd32, swisspidy, rachelbaker.
Fixes #38292.

Merges [40301] to the 4.7 branch.

[alexvorn2]

[deleted]