# Filters and hooks - Rateline 1.x documentation

> Add conditions, rule fields, columns and rates to the Table rate method from code.

Rateline's hooks are WordPress filters and actions. Put the examples in a small custom plugin or your child theme's `functions.php`. Rateline Pro is built on these same hooks.

## How a rate is worked out

1. `Method::lines()` turns the package's items that need shipping into lines: `qty`, `weight` (each), `total` (the line as customers see it) and `class` (0 for none). **`rateline_package_line`** can add more.
2. `Rules::rates()` takes the table's first rate and finds the first rule that matches the whole order: its shipping class fits, its condition's measure is in range (**`rateline_measure`** gives the measures), and **`rateline_rule_matches`** agrees.
3. **`rateline_rates`** can replace or add rates.
4. The method adds the handling fee, minimum and maximum, and applies free shipping coupons, to each rate.

## A condition of your own

A condition needs a label for the **When** column and a measure of the same key. This one checks the tallest item, from each product's height:

```php
// The height of each cart line's product.
add_filter( 'rateline_package_line', function ( $line, $item, $product ) {
	$line['height'] = (float) $product->get_height();
	return $line;
}, 10, 3 );

// The tallest item in the lines being priced.
add_filter( 'rateline_measure', function ( $measure, $lines ) {
	$measure['height'] = max( array_merge( array( 0 ), array_column( $lines, 'height' ) ) );
	return $measure;
}, 10, 2 );

// In the When column.
add_filter( 'rateline_conditions', function ( $conditions ) {
	$conditions['height'] = 'Tallest item (cm)';
	return $conditions;
} );
```

Rateline's own fields and measures (`qty`, `weight`, `total`, `class`; `weight`, `items`, `subtotal`) can't be replaced.

## A rule field and a check of your own

Register the field, show it as a column, and check it:

```php
add_filter( 'rateline_rule_fields', function ( $fields ) {
	return $fields + array( 'country' => '' );
} );

add_filter( 'rateline_rule_columns', function ( $columns ) {
	$columns['country'] = array(
		'title'  => 'Country',
		'class'  => 'my-col-country',
		'fields' => array( 'country' ),
		'cell'   => function ( $name, $rule ) {
			return '<td><input type="text" name="' . esc_attr( $name . '[country]' ) . '" value="' . esc_attr( $rule['country'] ) . '"></td>';
		},
	);
	return $columns;
} );

add_filter( 'rateline_rule_matches', function ( $matches, $rule, $package ) {
	return $matches && ( '' === $rule['country'] || $rule['country'] === ( $package['destination']['country'] ?? '' ) );
}, 10, 3 );
```

`rateline_clean_rule` gets each rule as it's saved, to tidy your field. Columns are drawn in array order, between the drag handle and the remove button; a field without a column is kept in a hidden input.

> [!WARNING]
> A rule with a value in a field no active plugin registers doesn't match. That keeps a table safe when the plugin that added the field is deactivated: its rules are skipped rather than applied to every order.

## Rates

`rateline_rates` gets the rates Rateline worked out (`name => array( 'cost' => float, 'label' => string )`, where `''` is the method's own) with the rules, lines, package and method. Return more rates, or other costs:

```php
// A weekend surcharge on the method's own rate.
add_filter( 'rateline_rates', function ( $rates ) {
	if ( isset( $rates[''] ) && in_array( gmdate( 'N' ), array( '6', '7' ), true ) ) {
		$rates['']['cost'] += 5;
	}
	return $rates;
} );
```

A named rate gets the rate ID `rateline:{instance}:{name}`; its label is the rule's label, else the name.

## Settings and the table footer

- `rateline_method_fields` gets the method's settings fields (WooCommerce settings API), in order, and the method. Read your own with `$method->get_option( 'key' )`.
- `rateline_rules_footer` fires at the end of the rules table's footer, after **+ Add rule**.

## When Rateline is loaded

`rateline_loaded` fires once Rateline has loaded (on `plugins_loaded`, only when WooCommerce is active). Hook your code there rather than checking for Rateline's classes. `RATELINE_VERSION` holds its version.

## Where the settings are

Each method's settings are in the option `woocommerce_rateline_{instance}_settings`, with the rules under `rules` as a list of arrays: `rate`, `condition`, `min`, `max`, `class`, `cost`, `per_item`, `per_unit`, `percent`, `label`, `hide`, and any fields add-ons register.

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