How do you set a default Fieldtype config value?

[Robin S]

In a Fieldtype module you can define config inputfields for a field that uses the Fieldtype in the ___getConfigInputfields($field) method. The saved values become properties of the Field object ($field). But how do you set a default value for a config inputfield in a way that doesn't prevent the user from clearing the default and leaving the inputfield empty? It's the first time I've had this need and I can't work out how to do it. I looked at the core Fieldtype modules but I couldn't find one that applies a default value that is allowed to be cleared.

A simple module to explain it more clearly:

<?php namespace ProcessWire;
class FieldtypeTest extends FieldtypeText {

	public static function getModuleInfo() {
		return array(
			'title' => 'Test Fieldtype',
			'summary' => 'Test default config values.',
			'version' => '0.1.0',
		);
	}

	/**
	 * Config inputfields
	 *
	 * @param Field $field
	 * @return InputfieldWrapper
	 */
	public function ___getConfigInputfields(Field $field) {
		$inputfields = parent::___getConfigInputfields($field);

		/*
		 * How can I set a default value for "greeting" in a way that
		 * doesn't prevent the user from saving an empty value?
		 *
		 * The below doesn't work because it will apply the default value
		 * when the user has attempted to clear it.
		 *
		 * */
		if(is_null($field->get('greeting'))) $field->set('greeting', 'Hello');

		$f = $this->wire()->modules->get('InputfieldText');
		$f->label = 'Greeting';
		$f->attr('name', 'greeting');
		$f->attr('value', $field->get('greeting'));
		$inputfields->add($f);
		return $inputfields;
	}

}

Does anyone know the right way to do this?

Maybe @ryan has a suggestion?

Thanks in advance.

[BitPoet]

Off the top of my head:

• In your module's install method, hook after modules::install()
• in that hook method, get the module config with modules::getConfig(), set your default value and do a modules::saveConfig()