Set minimum, maximum and step quantity programmatically for specific variable products in WooCommerce

Question

I use WooCommerce cart quantity won't change after cart update answer code to customize some product quantity arguments (as min, max and step arguments).

Now I have a variable product with product id 27525, and I want to apply another rule to this product only,
Quantity rule details: min(default) qty 1, max qty 24 and step 1.

I tried to use the code below, the problem is,
if no variations are selected, the default/min quantity will be 25, the rule is the same as the general quantity settings,
If I choose an available variation, the default quantity will be 24.

add_filter( 'woocommerce_available_variation', 'variation_quantity_input_args', 10, 2 );
function variation_quantity_input_args( $args, $product ) {
    $sample_product_id = array(27525);

    if (in_array( $product->get_id(), $sample_product_id)) {
        $args['min_qty'] = 1;
        $args['max_qty'] = 24;
        return $args;
    }
}

How to change the code and apply the rules to variable product 27525?

$args['min_qty'] = 1; //default and min qty
$args['max_qty'] = 24; // max qty
$args['step'] = 1; // Seems won't work use woocommerce_available_variation, but I want to change the step to 1

Answer 1

The woocommerce_available_variation hook has the WC_Product_Variation product object as its third parameter and not the variable product.

With the woocommerce_available_variation hook you cannot set the product step.

The available arguments are the following (source code of the WooCommerce /includes/class-wc-product-variable.php file @version 3.0.0):

return apply_filters(
    'woocommerce_available_variation',
    array(
        'attributes'            => $variation->get_variation_attributes(),
        'availability_html'     => wc_get_stock_html( $variation ),
        'backorders_allowed'    => $variation->backorders_allowed(),
        'dimensions'            => $variation->get_dimensions( false ),
        'dimensions_html'       => wc_format_dimensions( $variation->get_dimensions( false ) ),
        'display_price'         => wc_get_price_to_display( $variation ),
        'display_regular_price' => wc_get_price_to_display( $variation, array( 'price' => $variation->get_regular_price() ) ),
        'image'                 => wc_get_product_attachment_props( $variation->get_image_id() ),
        'image_id'              => $variation->get_image_id(),
        'is_downloadable'       => $variation->is_downloadable(),
        'is_in_stock'           => $variation->is_in_stock(),
        'is_purchasable'        => $variation->is_purchasable(),
        'is_sold_individually'  => $variation->is_sold_individually() ? 'yes' : 'no',
        'is_virtual'            => $variation->is_virtual(),
        'max_qty'               => 0 < $variation->get_max_purchase_quantity() ? $variation->get_max_purchase_quantity() : '',
        'min_qty'               => $variation->get_min_purchase_quantity(),
        'price_html'            => $show_variation_price ? '<span class="price">' . $variation->get_price_html() . '</span>' : '',
        'sku'                   => $variation->get_sku(),
        'variation_description' => wc_format_content( $variation->get_description() ),
        'variation_id'          => $variation->get_id(),
        'variation_is_active'   => $variation->variation_is_active(),
        'variation_is_visible'  => $variation->variation_is_visible(),
        'weight'                => $variation->get_weight(),
        'weight_html'           => wc_format_weight( $variation->get_weight() ),
    ),
    $this,
    $variation
);

To set the step to product variations you will need to use the woocommerce_quantity_input_args hook.

If you want to set the same step to all product variations you can use this hook.

The available arguments are the following (source code of the WooCommerce /includes/wc-template-functions.php file @version 2.5.0):

$defaults = array(
    'input_id'     => uniqid( 'quantity_' ),
    'input_name'   => 'quantity',
    'input_value'  => '1',
    'classes'      => apply_filters( 'woocommerce_quantity_input_classes', array( 'input-text', 'qty', 'text' ), $product ),
    'max_value'    => apply_filters( 'woocommerce_quantity_input_max', -1, $product ),
    'min_value'    => apply_filters( 'woocommerce_quantity_input_min', 0, $product ),
    'step'         => apply_filters( 'woocommerce_quantity_input_step', 1, $product ),
    'pattern'      => apply_filters( 'woocommerce_quantity_input_pattern', has_filter( 'woocommerce_stock_amount', 'intval' ) ? '[0-9]*' : '' ),
    'inputmode'    => apply_filters( 'woocommerce_quantity_input_inputmode', has_filter( 'woocommerce_stock_amount', 'intval' ) ? 'numeric' : '' ),
    'product_name' => $product ? $product->get_title() : '',
    'placeholder'  => apply_filters( 'woocommerce_quantity_input_placeholder', '', $product ),
);

If you want to manage the product step, the minimum quantity and the maximum quantity as a custom meta of the product, see @LoicTheAztec's answer:

• Set quantity minimum, maximum and step at product level in Woocommerce

ANSWER

To answer your question, if you want all product variations that have the parent variable product id equal to 27525 to have the following values:

• Min quantity: 1
• Max quantity: 24
• Step: 1

You can use the following functions:

It works in the product page, in the cart and in the loop.

// set the min and max quantity for each product variation (based on the variable product id)
add_filter( 'woocommerce_available_variation', 'variation_quantity_input_args', 10, 3 );
function variation_quantity_input_args( $args, $product, $variation ) {
    // set variable product ids
    $sample_product_id = array( 27525 );
    // if the selected variation belongs to one of the variable product ids
    // set the min and max quantity
    if ( in_array( $variation->get_parent_id(), $sample_product_id ) ) {
        $args['min_qty'] = 1;
        $args['max_qty'] = 24;
        return $args;
    }
    return $args;
}


// set the step for specific variable products (and for each product variation)
add_filter( 'woocommerce_quantity_input_args', 'set_step_for_specific_variable_products', 10, 2 );
function set_step_for_specific_variable_products( $args, $product ) {
    // set variable product ids
    $sample_product_id = array( 27525 );
    
    // on the product page
    if ( ! is_cart() ) {
        // if the id of the variable product is in the array
        if ( in_array( $product->get_id(), $sample_product_id ) ) {
            $args['input_value'] = 1;
            $args['min_value'] = 1;
            $args['max_value'] = 24;
            $args['step'] = 1;
        }
    // in the cart
    } else {
        // if the id of the product variation belongs to a variable product present in the array
        if ( in_array( $product->get_parent_id(), $sample_product_id ) ) {
            $args['min_value'] = 1;
            $args['step'] = 1;
        }
    }
    return $args;
}

The code has been tested and works. Add it to your active theme's functions.php.