PHP Filters

Swft Checkout filters

swft_session_extensions

The primary extension hook. Add arbitrary structured data to the checkout session. Data is stored in the session, available in the checkout frontend as window.__SWFT_SESSION__.extensions, and written to the WooCommerce order as _swft_ext_{key} meta on payment completion.

apply_filters( 'swft_session_extensions', array $extensions, WC_Cart $cart ): array

Parameters:

Parameter	Type	Description
$extensions	array	Current extensions object. Initially empty []. May already contain keys from other plugins.
$cart	WC_Cart	The current WooCommerce cart object.

Return: array — the modified extensions array. Keys must be strings. Values may be any JSON-serialisable type.

Example:

add_filter( 'swft_session_extensions', function( array $extensions, WC_Cart $cart ): array {
    $extensions['gift_options'] = [
        'message' => WC()->session->get( 'gift_message' ) ?? '',
        'wrap'    => (bool) WC()->session->get( 'gift_wrap' ),
    ];
    return $extensions;
}, 10, 2 );

Data flow:

WP plugin → swft_session_extensions filter
  → payload['extensions']['gift_options'] = { message: '...', wrap: true }
  → POST api.swft.co.uk/sessions
  → stored in Supabase + Cloudflare KV
  → window.__SWFT_SESSION__.extensions.gift_options
  → WooCommerce order meta: _swft_ext_gift_options = '{"message":"...","wrap":true}'

---

swft_session_line_item

Modify or exclude a single line item before it is added to the session payload. Return null or false to exclude the item (e.g. if your plugin represents it differently in the extensions object).

apply_filters( 'swft_session_line_item', array $line_item, array $cart_item, WC_Product $product, string $cart_item_key ): array|null|false

Parameters:

Parameter	Type	Description
$line_item	array	The built line item. See structure below.
$cart_item	array	Raw WooCommerce cart item data from WC()->cart->get_cart().
$product	WC_Product	The product object.
$cart_item_key	string	The cart item key.

Line item structure:

[
    'product_id'   => int,
    'variation_id' => int|null,
    'name'         => string,
    'quantity'     => int,
    'price'        => int,     // minor units (pence)
    'subtotal'     => int,     // minor units
    'total'        => int,     // minor units
    'tax'          => int,     // minor units
    'image_url'    => string|null,
    'sku'          => string|null,
    'attributes'   => object,  // variation attributes as key-value pairs
]

Example — add custom meta to a line item:

add_filter( 'swft_session_line_item', function( array $item, array $cart_item, WC_Product $product ): array {
    $item['engraving_text'] = $cart_item['engraving_text'] ?? '';
    return $item;
}, 10, 3 );

Example — exclude a virtual line item:

add_filter( 'swft_session_line_item', function( $item, array $cart_item, WC_Product $product ) {
    if ( $product->is_virtual() && $product->get_sku() === 'GIFT_WRAP_FEE' ) {
        return null; // exclude from line items — handled via extensions instead
    }
    return $item;
}, 10, 3 );

---

swft_session_line_items

Modify all line items after the loop, before they are added to the payload.

apply_filters( 'swft_session_line_items', array $line_items, WC_Cart $cart ): array

Parameters:

Parameter	Type	Description
$line_items	array	Array of all built line item arrays.
$cart	WC_Cart	The current cart.

Example — sort line items by name:

add_filter( 'swft_session_line_items', function( array $items ): array {
    usort( $items, fn( $a, $b ) => strcmp( $a['name'], $b['name'] ) );
    return $items;
} );

---

swft_session_shipping_methods

Modify the available shipping methods passed to the checkout.

apply_filters( 'swft_session_shipping_methods', array $shipping_methods, WC_Cart $cart ): array

Parameters:

Parameter	Type	Description
$shipping_methods	array	Array of shipping method arrays. Each has id, name, price (minor units), description.
$cart	WC_Cart	The current cart.

Example — add a custom shipping option:

add_filter( 'swft_session_shipping_methods', function( array $methods, WC_Cart $cart ): array {
    if ( $cart->get_subtotal() >= 50 ) {
        $methods[] = [
            'id'          => 'click_collect',
            'name'        => 'Click & Collect',
            'price'       => 0,
            'description' => 'Collect from our store in 2 hours',
        ];
    }
    return $methods;
}, 10, 2 );

---

swft_session_customer

Modify the pre-filled customer data. Used to pre-fill the details step for logged-in customers.

apply_filters( 'swft_session_customer', array $customer, WC_Customer $wc_customer ): array

Parameters:

Parameter	Type	Description
$customer	array	`[‘email’ => string
$wc_customer	WC_Customer	The WooCommerce customer object.

Example:

add_filter( 'swft_session_customer', function( array $customer, WC_Customer $wc_customer ): array {
    // Add phone number for pre-fill
    $customer['phone'] = $wc_customer->get_billing_phone() ?: null;
    return $customer;
}, 10, 2 );

---

swft_session_totals

Modify the totals sent to the Swft API. All values are integers in minor units (pence/cents).

apply_filters( 'swft_session_totals', array $totals, WC_Cart $cart ): array

Parameters:

Parameter	Type	Description
$totals	array	['subtotal' => int, 'tax' => int, 'discount' => int] — all in minor units.
$cart	WC_Cart	The current cart.

---

swft_session_payload

Last-resort filter. Modify the complete payload before it is sent to the Swft API. Use specific filters above where possible.

apply_filters( 'swft_session_payload', array $payload ): array

Payload structure:

[
    'merchant_api_key' => string,
    'cart_hash'        => string,
    'currency'         => string,   // ISO 4217 (e.g. 'GBP')
    'line_items'       => array,
    'shipping_methods' => array,
    'subtotal'         => int,      // minor units
    'tax'              => int,
    'discount'         => int,
    'customer'         => array,
    'extensions'       => array,
    'meta'             => [
        'store_url'      => string,
        'needs_shipping' => bool,
        'needs_payment'  => bool,
        'wc_version'     => string,
        'plugin_version' => string,
    ],
]

---

Swft Cart filters

swftcart_cart_data

Modify the full cart object before it is rendered in the cart drawer.

apply_filters( 'swftcart_cart_data', array $cart_data ): array

---

swftcart_cart_item

Modify a single cart item before rendering.

apply_filters( 'swftcart_cart_item', array $item, string $cart_item_key ): array

---

swftcart_modules

Override the enabled/disabled state of modules.

apply_filters( 'swftcart_modules', array $modules ): array

$modules is an associative array of option_name => bool. See Modules for all option names.

---

swftcart_i18n

Override any UI string in the cart drawer.

apply_filters( 'swftcart_i18n', array $strings ): array

Example:

add_filter( 'swftcart_i18n', function( array $strings ): array {
    $strings['checkout_button'] = 'Proceed to secure checkout';
    $strings['empty_cart']      = 'Your bag is empty';
    return $strings;
} );

---

swftcart_announcements

Set the content of the announcement bar module.

apply_filters( 'swftcart_announcements', array $announcements ): array

Each announcement is an array with text (string) and optionally url (string) and icon (string).

Example:

add_filter( 'swftcart_announcements', function(): array {
    return [
        [
            'text' => 'Free delivery on orders over £50',
            'icon' => 'truck',
        ],
        [
            'text' => '10% off your first order — use WELCOME10',
            'url'  => '/shop/',
        ],
    ];
} );

---

swftcart_theme_vars

Override CSS custom property values for the cart drawer theme.

apply_filters( 'swftcart_theme_vars', array $vars ): array

See Themes for the full variable list.

---

swftcart_delivery_data

Set the data for the delivery countdown module.

apply_filters( 'swftcart_delivery_data', array $data ): array

Structure:

[
    'cutoff_time'    => '14:00',       // 24h time — order by this time for same-day
    'timezone'       => 'Europe/London',
    'message_before' => 'Order in {time} for same-day dispatch',
    'message_after'  => 'Order now for next-day dispatch',
]

---

swftcart_upsell_ids

Set the product IDs shown in the upsell module.

apply_filters( 'swftcart_upsell_ids', array $ids ): array

Example — return bestsellers dynamically:

add_filter( 'swftcart_upsell_ids', function( array $ids ): array {
    $bestsellers = wc_get_products( [
        'limit'   => 6,
        'orderby' => 'popularity',
        'order'   => 'DESC',
        'status'  => 'publish',
    ] );
    return array_map( fn( $p ) => $p->get_id(), $bestsellers );
} );