# Filters and hooks - Slotline 1.x documentation

> Change the first bookable date, close dates, skip the date for some carts, and build add-ons with Slotline's schedule, slot and settings hooks.

Slotline's hooks let a theme or plugin change which dates customers can book, and let add-ons (such as Slotline Pro) add schedules, slot fields and settings. Add the code to a small plugin or your child theme's `functions.php`.

## Dates

### `slotline_earliest_date`

The first date customers can choose, as `Y-m-d` in the store's time zone. Return the later of your date and the one passed in, so other plugins' limits still apply.

```php
// Nothing before the shop reopens on March 2.
add_filter( 'slotline_earliest_date', function ( $date, $type, $products ) {
	$reopen = '2027-03-02';
	return ( '' === $date || $reopen > $date ) ? $reopen : $date;
}, 10, 3 );
```

`$type` is `delivery` or `pickup`; `$products` is the product IDs being booked, or `null` for the cart's.

### `slotline_closed_dates`

More dates nobody can book, on top of the closed dates in the settings. Same arguments.

```php
add_filter( 'slotline_closed_dates', function ( $dates ) {
	$dates[] = '2027-04-18'; // The van's annual service.
	return $dates;
} );
```

### `slotline_needs_date`

Whether the cart asks for a date at all (`true`, `$type`). Return `false` to skip it, e.g. for a cart that only holds gift cards that still ship.

### `slotline_now`

The current time Slotline uses (a timestamp). Useful in tests.

## Statuses and labels

Orders take a place in their slot unless they're cancelled, failed, refunded or an unfinished Checkout block draft. The date and slot show through WooCommerce's `woocommerce_get_order_item_totals` (row key `slotline`), so you can move or restyle that row with the same filter at a later priority.

## Building an add-on

Slotline fires `slotline_loaded` once it has loaded (on `plugins_loaded`, only when WooCommerce is active). Hook your features there; `SLOTLINE_VERSION` tells you which Slotline you're running with.

| Hook | Use |
|---|---|
| `slotline_schedules` | Add schedule keys to `['delivery']`. A schedule's settings are options `slotline_{key}_{field}`, like delivery's, and Slotline offers and books it like its own |
| `slotline_schedule_type`, `slotline_schedule_name` | The type (`delivery` or `pickup`) and the name of your schedule (`$value, $key`) |
| `slotline_schedule_defaults` | Default settings by type (`$defaults, $type`) |
| `slotline_cart_schedule` | The schedule the cart books (`$key, $type, $rate`): Slotline passes `delivery`, or `''` for a pickup |
| `slotline_slot` | Read your own field from a saved slot row (`$slot, $row`) |
| `slotline_slot_columns` | Add a column to the time slots table (`$columns, $option_id`): `key => [ 'label' => …, 'cell' => callable( $name, $slot ), 'desc' => … ]` |
| `slotline_save_slot` | Save your column (`$row, $posted`) |
| `slotline_slot_notes` | Notes after a slot at checkout, e.g. "+$5.00" (`$notes, $slot, $schedule`) |
| `slotline_settings` | The settings fields; `Extendiment\Slotline\Admin\SettingsSection::schedule_fields( $key, $title )` builds a schedule's section |
| `slotline_checkout_booked` | Action: the cart's choice was booked on its new order (`$order, $schedule, $date, $slot`) |
| `slotline_booking_changed` | Action: the store changed an order's booking on the order screen (`$order, $before`) |

The booking is order meta: `_slotline_type`, `_slotline_date` (Y-m-d), `_slotline_slot` (e.g. `09:00-12:00`, empty for a date only) and `_slotline_schedule` (only for a schedule that isn't the type's own). Read it with `Extendiment\Slotline\Bookings`; `Bookings::between( $from, $to )` finds booked orders and works with both order storages.

Source: https://extendiment.com/plugins/slotline/docs/1.x/filters-and-hooks