WP Snippet: Min Quantity by Category for Woo

Enforces a minimum purchase quantity for Woo products assigned to selected product categories. Selected categories can be excluded (for example a "sets" subcategory where a single item may be bought).

Features

• Minimum quantity per category list, step stays 1 (6, 7, 8...)
• Quantity below the minimum is raised automatically with a notice, no hard error
• Works on the product page, add to cart (including AJAX), classic cart and block cart (Store API)
• Variable products: the rule is checked on the parent product
• Excluded categories override included ones
• Fixes items already in the cart when the rule changes
• No admin UI, configuration by constants
• Unique prefix (torwald45mqc) for all functions, constants and filters

Configuration

Add to wp-config.php:

define( 'TORWALD45_MQC_INCLUDE', 'flies' );
define( 'TORWALD45_MQC_EXCLUDE', 'sets' );
define( 'TORWALD45_MQC_MIN', 6 );

• TORWALD45_MQC_INCLUDE - product_cat slugs, comma separated. Without it the snippet does nothing.
• TORWALD45_MQC_EXCLUDE - product_cat slugs, comma separated (optional).
• TORWALD45_MQC_MIN - minimum quantity (default 6).

Per product override with a filter:

add_filter( 'torwald45_mqc_min', function ( $min, $product_id ) {
    return 123 === $product_id ? 12 : $min;
}, 10, 2 );

Installation

Method 1: Code Snippets plugin - paste the content of torwald45-mqc.php without the opening <?php tag.

Method 2: mu-plugin - copy torwald45-mqc.php to wp-content/mu-plugins/.

Method 3: functions.php - paste the content into your child theme functions.php.

Notes

• Category match is direct: the product must be assigned to the category itself. Child categories are not included automatically - list them in TORWALD45_MQC_INCLUDE if needed.
• Adding a product that is already in the cart adds at least the minimum again.

Requirements

• WP 6.5 or higher
• Woo 8.0 or higher
• PHP 7.4 or higher

License

GPL-2.0-or-later

Author

Torwald45