If you want to call a file within a temple in WordPress, it is recommend to use get_template_part() instead of the PHP include() function. get_template_part() provides a simple mechanism for child themes to overload reusable sections of code in the theme.
Use get_template_part() to include a file in a template
Syntax
get_template_part( $slug, $name = null );
It first loads the template “{slug}-{name}.php” if $name is not empty. If $name is empty or the template “{slug}-{name}.php” does not exist, it loads “{slug}.php”. If “{slug}.php” still does not exist, no file will be included. Note you won’t get warnings if it fails to find any matching file.
Examples
Below example includes a navigation bar in the header.php template file.
get_template_part( 'template-parts/navigation/navigation', 'nav-bar' );
In the case of a child theme is being used, assuming that the parent theme is twentynineteen, and the child theme is twentynineteen-child, the code above includes the first existing file among these files in this priority:
- wp-content/themes/twentynineteen-child/template-parts/navigation/navigation/nav-bar.php
- wp-content/themes/twentynineteen/template-parts/navigation/navigation/nav-bar.php
- wp-content/themes/twentynineteen-child/template-parts/navigation/navigation/nav-bar.php
- wp-content/themes/twentynineteen/template-parts/navigation/navigation/nav-bar.php
Using include() to include a file in a template
If you still want to directly include a file using include_once() or require_once(), see below examples.
Example 1: Include a file from the parent theme
If a child theme is being used, get_template_directory() returns the absolute path of the parent theme.
require_once( get_template_directory() . '/inc/my-functions.php' );
Example 2: Include a file from the child theme
If a child theme is being used, get_stylesheet_directory() returns the absolute path of the child theme.
require_once( get_stylesheet_directory() . '/inc/my-functions.php' );