Low Variables

Anatomy of a Variable Type

Below is the skeleton of a variable type, containing all possible properties and methods.

class My_new_type extends Low_variables_type {

	public $info             = array();
	public $assets           = array();
	public $language_files   = array();
	public $default_settings = array();

	public function display_input($var_id, $var_data, $var_settings)
	{
		// ...
	}

	public function save_input($var_id, $var_data, $var_settings)
	{
		// ...
	}

	public function post_save_input($var_id, $var_data, $var_settings)
	{
		// ...
	}

	public function display_output($tagdata, $row)
	{
		// ...
	}

	public function display_settings($var_id, $var_settings)
	{
		// ...
	}

	public function save_settings($var_id, $var_settings)
	{
		// ...
	}

	public function post_save_settings($var_id, $var_settings)
	{
		// ...
	}

	public function delete($var_id)
	{
		// ...
	}
}

Properties

$info

(array) — contains basic information about the Variable Type.

public $info = array(
	'name'    => 'My variable type name',
 	'version' => '1.0.0'
);

$assets

(array) — if the variable type has external css and/or javascript, this contains their references. Use the keys css and js, and set their values to the relative path to the assets. The files should be put inside the /themes/low_variables/types/your_variable_type/ folder. If you need to load multiple files, use an array as value.

public $assets = array(
	'css' => 'css/extra_styles.css',
	'js'  => array(
		'js/my_custom_plugin.js',
		'js/another_plugin.js'
	)
);

$language_files

(array) — if the variable type uses any language file, this contains their references. You can load any of the available language files by calling their name.

public $language_files = array(
	'my_variable_type_name',
	'upload',
	'image_lib'
);

$default_settings

(array) — if the variable type has settings, this contains all settings and their default values.

public $default_settings = array(
	'height'        => '100',
	'member_groups' => array(1),
	'separator'     => 'pipe'
);

Methods

display_input

Use this method to display the input field used to enter the value of the variable. Note: The name of the input field should be var[{$var_id}].

Arguments

• $var_id (int) — the ID of the variable.
• $var_data (string) — the current value the variable.
• $var_settings (array or bool) — the current type settings FALSE if no settings exist.

Returns

A string containing the HTML to display the input field of the given variable.

save_input

This method is called just before the value of the variable is saved to the database. Use it to alter or evaluate the value before it is saved.

Arguments

• $var_id (int) — the ID of the variable.
• $var_data (string) — the posted value the variable.
• $var_settings (array or bool) — the current type settings FALSE if no settings exist.

Returns

A string containing the new value of the variable or FALSE if the variable must not be saved (skipped). If you return FALSE, be sure to enter a value into $this->error_msg for displaying an error message.

post_save_input (v1.3.7+)

This method is called after the value of the variable is saved to the database. Use it for extra processing after it is saved.

Arguments

• $var_id (int) — the ID of the variable.
• $var_data (string) — the posted value the variable.
• $var_settings (array or bool) — the current type settings FALSE if no settings exist.

Returns

NULL

display_output

Use this method to display custom output of the variable value. It is used by the exp:low_variables:parse, exp:low_variables:single and exp:low_variables:pair template tags.

Arguments

• $tagdata (string) — the template tagdata.
• $row (array) — array containing the current variable details. Keys: variable_id, variable_name, variable_data, variable_label, variable_type and variable_settings.

Returns

A string with modified tagdata.

display_settings

If your variable type has settings, use this to display them in the Manage Variable form. Note: Use the function $this->input_name('my_custom_setting') for the setting input names.

Arguments

• $var_id (int or string) — the ID of the variable or new if the variable is new.
• $var_settings (array or bool) — the current type settings FALSE if no settings exist.

Returns

An array containing the HTML of all the settings. Per setting, use an array with two values; the first one for the setting label, the second one for the setting input field.

save_settings

This method is called just before the settings of a (new) variable is saved to the database. Use it to alter or evaluate the settings before they are saved.

Arguments

• $var_id (int or string) — the ID of the variable or new if the variable is new.
• $var_settings (array or bool) — the current type settings FALSE if no settings exist.

Returns

An array containing the (modified) settings.

post_save_settings (v2.2.0+)

This method is called just after the settings of a (new) variable is saved to the database. Use it for extra processing after it is saved.

Arguments

• $var_id (int) — the ID of the variable.
• $var_settings (array or bool) — the current type settings FALSE if no settings exist.

Returns

NULL

delete (v2.2.0+)

This method is called just before a variable is deleted. Use it for extra processing before it is deleted permanently.

Arguments

• $var_id (int) — the ID of the variable.

Returns

NULL