silverstripe-framework/forms/SingleSelectField.php

<?php

/**
 * Represents the base class for a single-select field
 */
abstract class SingleSelectField extends SelectField {

	/**
	 * Show the first <option> element as empty (not having a value),
	 * with an optional label defined through {@link $emptyString}.
	 * By default, the <select> element will be rendered with the
	 * first option from {@link $source} selected.
	 *
	 * @var bool
	 */
	protected $hasEmptyDefault = false;

	/**
	 * The title shown for an empty default selection,
	 * e.g. "Select...".
	 *
	 * @var string
	 */
	protected $emptyString = '';

	/**
	 * @param boolean $bool
	 * @return self Self reference
	 */
	public function setHasEmptyDefault($bool) {
		$this->hasEmptyDefault = $bool;
		return $this;
	}

	/**
	 * @return bool
	 */
	public function getHasEmptyDefault() {
		return $this->hasEmptyDefault;
	}

	/**
	 * Set the default selection label, e.g. "select...".
	 * Defaults to an empty string. Automatically sets
	 * {@link $hasEmptyDefault} to true.
	 *
	 * @param string $string
	 */
	public function setEmptyString($string) {
		$this->setHasEmptyDefault(true);
		$this->emptyString = $string;
		return $this;
	}

	/**
	 * @return string
	 */
	public function getEmptyString() {
		return $this->emptyString;
	}

	/**
	 * Gets the source array, including the empty string, if present
	 *
	 * @return array|ArrayAccess
	 */
	public function getSourceEmpty() {
		// Inject default option
		if($this->getHasEmptyDefault()) {
			return array('' => $this->getEmptyString()) + $this->getSource();
		} else {
			return $this->getSource();
		}
	}

	/**
	 * Validate this field
	 *
	 * @param Validator $validator
	 * @return bool
	 */
	public function validate($validator) {
		// Check if valid value is given
		$selected = $this->Value();
		if(strlen($selected)) {
			// Use selection rules to check which are valid
			foreach($this->getValidValues() as $formValue) {
				if($this->isSelectedValue($formValue, $selected)) {
					return true;
				}
			}
		} else {
			if ($this->getHasEmptyDefault()) {
				// Check empty value
				return true;
			}
			$selected = '(none)';
		}

		// Fail
		$validator->validationError(
			$this->name,
			_t(
				'DropdownField.SOURCE_VALIDATION',
				"Please select a value within the list provided. {value} is not a valid option",
				array('value' => $selected)
			),
			"validation"
		);
		return false;
	}

	public function castedCopy($classOrCopy) {
		$field = parent::castedCopy($classOrCopy);
		if($field instanceof SingleSelectField && $this->getHasEmptyDefault()) {
			$field->setEmptyString($this->getEmptyString());
		}
		return $field;
	}

}