I'm a new WordPress developer and recently I've been having problems (on multiple sites) with include_once and require_once for PHP files. If I include (get_theme_directory_uri() . 'subdir/file') the specified file gets included (or required, which leads to fatal errors) but if any WordPress functions are called within 'file' I get something similar to:

'Call to undefined function add_action() in /full/path/to/file'.

The apparent solution I've found is to do:

include(dirname(__FILE__) . "/subdir/filename");

Is this right or did I miss 'the WordPress way' to include files somewhere?


3 Answers 3


If you check https://codex.wordpress.org/Function_Reference/get_template_directory_uri

You will see get_template_directory_uri() returns a uri, not a server path.

You should use instead the get_template_directory() function, which returns the path to the theme, without trailing slash:

include get_template_directory() . '/subdir/filename.php';

For a plugin you can use the plugin_dir_path() function:

include plugin_dir_path( __FILE__ ) . '/subdir/filename.php';
  • I want to note that this is mostly intended for locating paths in arbitrary plugin. Within inside of specific plugin the relative paths are known and basic PHP includes (sans any WP bits) are a normal practice.
    – Rarst
    Oct 27, 2015 at 17:46
  • With Rarst comment i realized my anwser is for plugins, not themes. For themes, use get_template_directory() instead of get_template_directory_uri(). Easy! Oct 27, 2015 at 17:58
  • 3
    you might want to try - /subdir/filename.php?
    – Jon
    Apr 15, 2019 at 8:53
  • @Jon thanks, same observation. Submitted an edit to the answer.
    – kontur
    Feb 16 at 12:44

WordPress 4.7+ introduce get_theme_file_path() functions to include file on WordPress theme.

Include like this:

include get_theme_file_path( '/subdir/filename.php' );

The advantage of using this function is on child theme you can override the parent theme file.

Reference : https://developer.wordpress.org/reference/functions/get_theme_file_path/

  • 1
    Exactly what I was looking for! This should be the correct answer now.
    – Oneezy
    Aug 23, 2019 at 13:04
  • Exactly, WP updated the helper to do so, this is the good answer. Sep 16, 2020 at 16:24

In the following examples, I assume you are using composer and a child theme might be enabled or not.

  1. Use this method if you want to include a file within a theme and want to ensure the parent theme's directory is used even if a child theme is enabled:
require get_template_directory() . '/vendor/autoload.php';
  1. Or use this method if you want to include a file within a theme and don't mind whether the parent theme's directory is used or the child theme's directory is used if a child theme is enabled:
require get_stylesheet_directory() . '/vendor/autoload.php';
  1. And lastly, use this method if you want to include a file within a plugin:
require __DIR__ . '/vendor/autoload.php';

Be careful with the last method because the magic constant __DIR__ will have a different value depending on the directory in which your php file is located.

Note that there's no benefit to using the plugin_dir_path() function as it is just a wrapper to the trailingslashit() function.

The documentation says:

The “plugin” part of the name is misleading – it can be used for any file, and will not return the directory of a plugin unless you call it within a file in the plugin’s base directory.

See https://developer.wordpress.org/reference/functions/plugin_dir_path/ for more details.

Also note that using include is poor practice because a missing file will only raise a warning. Always use require instead, because a missing file will raise a fatal error and won't stay unnoticed.

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