Background

I’m developing a plugin for WordPress. I initially used file_get_contents() for two purposes:

1. A remote file (which I changed to wp_remote_post())
2. A local file in the plugin dir (what this question is about)

WordPress staff told me to NOT use file_get_contents() for remote _POST requests (usage 1. above), but to use wp_remost_post() instead.

From their email concerning usage 1. (above):

Using file_get_contents on remote files

Many hosts block the use of file_get_contents on remote content. This is a security measure that we fully endorse.

Thankfully, WordPress comes with an extensive HTTP API that can be used instead. It’s fast and more extensive than most home-grown alternatives. It’ll fall back to curl if it has to, but it’ll use a lot of WordPress’ native functionality first.

So, I did. But…

Solving usage 1. A remote file (above) got me to reading and thinking about a better tool for usage 2. A local file (above)

In the WordPress HTTP API docs, there is no alternative for file_get_contents() on local files, nothing like wp_file_get_contents().

(I understand this may seem strange since local files of a plugin are often static, but I am writing extra files to save cost, and I politely don’t want to open that discussion. Besides, this approved plugin from someone else, code here, uses file_get_contents(), thus proving my own need is legitimate, but it doesn’t prove that file_get_contents() is ‘proper’ WordPress-practice.)

From this blog post, clearly this was a big discussion for file_get_contents() for remote files. But, I don’t see much on the web about a WordPress function for local files. From the post:

Like many others I’ve used the native PHP function file_get_contents() to receive the content from a remote file because the functions is very easy to use. But is it the best way to do that? I see many scripts using that function and even WordPress plugins are using this function while WordPress has a native function to receive remote content.

…I want to take that discussion to local files and build this plugin right.

My code (current and attempted)

I simply need to confirm whether a local file in the plugin directory exists, then confirm whether it contains a certain string. I thought it best to use file_get_contents() for local files in PHP from this question on SE. But, this is WordPress. Currently, I am using:

if ( ( ! $wp_filesystem->exists ( $check_this_file ) )
 || (strpos ( file_get_contents ( $check_this_file ),
    $check_this_string ) === false ) )

I tried using WP_Filesystem_Direct::get_contents instead:

if ( ( ! $wp_filesystem->exists ( $check_this_file ) )
 || (strpos ( WP_Filesystem_Direct::get_contents ( $check_this_file ),
    $check_this_string ) === false ) )

…but I got this error:

Deprecated: Non-static method WP_Filesystem_Direct::get_contents() should not be called statically

What should I do?

I’m not sure because there isn’t even a #get-contents tag on WP.SE at the time of asking, but the function exists both in the framework and in the docs.

I want to know the “WordPress way” for plugins to read a plugin file’s contents for a string test:

• file_get_contents() (what I have now)
• WP_Filesystem_Direct::get_contents() (but how do I make it work without the error?)
• or some proper-reliable usage of wp_filesystem() or similar