WooCommerce - Call to undefined function is_woocommerce()

Question

WooCommerce - Call to undefined function is_woocommerce()

Omer

2021年9月30日 03:52

new here and to wordpress plugins development, go easy on me :D

Anyway, I am trying to create a new plugin and I am getting a 500 error. I changed WP_DEBUG in config.php to true in order to see what is causing the 500 error and got this message:

Fatal error: Uncaught Error: Call to undefined function is_woocommerce() in...

This is my code currently:

?php
/**
 * Plugin Name: 
 * Plugin URI: 
 * Description: 
 * Author: 
 * Author URI: 
 * Version: 1.0
 * Text Domain: 
 *
 * Copyright: (c) 2018
 *
 * License: 
 * License URI: 
 *
 * @author    
 * @copyright Copyright (c) 2018
 * @license   
 *
 */
//
defined( 'ABSPATH' ) or exit;
if (function_exists(is_woocommerce())) {
    echo "test: ".is_woocommerce();
} else {
    echo "test: Function does not exists!";
}

If you need any more information, tell me and I'll edit the question. Help will be appreciated, thanks!

Topic 500-internal-error plugin-development plugins Wordpress

Category Web

Michael Ecklund · Accepted Answer · 2020年4月29日 15:55

This may or may not be a relevant answer.

However, I was receiving a very similar error after updating the Divi theme.

Uncaught Error: Call to undefined function et_is_woocommerce_plugin_active()

I deleted the old Divi directory in the theme directory and replaced with the new Divi directory.

I tend to also delete the directory /wp-content/et-cache as well, when updating Divi.

Anyways, long story short, I ran this WP CLI command after updating the Divi theme.

wp transient delete --all --skip-packages --skip-themes --skip-plugins

The error was immediately resolved, and the updated Divi theme was functioning as expected once again.

Nazaria · Accepted Answer · 2018年7月28日 01:05

If you want to check one Plugin's Function / Class etc. from another Plugin, then it's best to use a hook like plugins_loaded.

Based on this, your Plugin CODE will look like:

<?php
/*
Plugin Name: YOUR PLUGIN NAME
*/

defined( 'ABSPATH' ) or exit;

add_action( 'plugins_loaded', 'plugin_prefix_woocommerce_check' );
    function plugin_prefix_woocommerce_check() {
    if( function_exists( 'is_woocommerce' ) ) { 
        add_action( "wp_footer", "wpse_woocommerce_exists" );
    }   
    else {
        add_action( "wp_footer", "wpse_woocommerce_doesnt_exist" );
    }   
}   

function wpse_woocommerce_exists() {
    echo "<h1>WooCommerce Exists!</h1>";
}   

function wpse_woocommerce_doesnt_exist() {
    echo "<h1>WooCommerce Doesn't Exists!</h1>";
}

Directly checking other plugin functions will often lead to error, since WordPress may not be done loading other plugins by the time your CODE executes. However, when WordPress is done, it'll fire the plugins_loaded hook.

Check Plugin Development Guide for more information on how to develop a WordPress Plugin.

WooCommerce - Call to undefined function is_woocommerce()

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