[isValid description].

@param [type] $key [description]

@return bool [description]
540138
public function isValid($key = null)
    {
        if (parent::isValid() && $this->getKey()) {
            return $key && $this->getKey() && $this->chiper->decrypt($this->getKey()) == $this->chiper->decrypt($key);
        }

        return false;
    }
1078004
protected function validateKey(/*# string */ &$key)
    {
        // validate key
        if (is_string($key)) {
            $key = trim($key);
            return;
        }

        // throw exception
        throw new InvalidArgumentException(
            Message::get(Message::CACHE_INVALID_KEY, $key),
            Message::CACHE_INVALID_KEY
        );
    }
1010373
public function offsetExists($key): bool
    {
        assert(
            is_string($key),
            sprintf('Invalid metadata key: (%s) %s', gettype($key), VarPrinter::toString($key))
        );

        return $this->has($key);
    }
1347059
protected function isKeyAllowed($key)
    {
        /*
         * Let the core columns through
         */
        if ($key == 'id' || $key == 'value' || $key == 'item') {
            return true;
        }

        /*
         * Let relations through
         */
        if ($this->model->hasRelation($key)) {
            return true;
        }

        return false;
    }
998508
public function isValidated($key= '') {
        $unvalidated = array_diff($this->_dirty, $this->_validated);
        if (empty($key)) {
            $validated = (count($unvalidated) > 0);
        } else {
            $validated = !in_array($this->getField($key), $unvalidated);
        }
        return $validated;
    }
4839
public function __isset($key)
	{
		if (isset($this->$key) && (!is_null($this->$key))) {
			return true;
		}
		if (!isset($this->specificationExtensions[$key])) {
			return false;
		}
		return !is_null($this->specificationExtensions[$key]);
	}
892762
public static function validateKey($key)
    {
        if (!\is_string($key)) {
            throw new InvalidArgumentException(sprintf('Cache key must be string, "%s" given', \is_object($key) ? \get_class($key) : \gettype($key)));
        }
        if ('' === $key) {
            throw new InvalidArgumentException('Cache key length must be greater than zero');
        }
        if (false !== strpbrk($key, '{}()/\@:')) {
            throw new InvalidArgumentException(sprintf('Cache key "%s" contains reserved characters {}()/\@:', $key));
        }

        return $key;
    }
1198222
protected function isPk($key)
    {
        $pk = $this->getPk();
        if (is_string($pk) && $pk == $key) {
            return true;
        } elseif (is_array($pk) && in_array($key, $pk)) {
            return true;
        }

        return false;
    }
984930
public function isValid($api_key)
    {
        if (!$api_key) {
            return false;
        }

        return ($this->event_hash == $this->calculateHash($api_key))
            ? true : false;
    }
1193634
public static function issetValue(string $key): bool
    {
        $key = \mb_strtolower($key);
        return isset(self::$_data[$key]);
    }
882849
public function __isset( $key ) 
	{
		return ( array_key_exists( $key, $this->_data_store ) || method_exists( $this, '_get_modifier_'.$key ) ) ? true : false;
	}
170730
public static function has( $key )
	{
		$cache = self::instance();
		if ( $cache ) {
			return $cache->isExisting( $key );
		}
		return false;
	}
483081
public function isValid( $key = null ) {
		$key = $key ? $this->sanitizeKey( $key ) : $this->getKey();
		return strlen( $key ) === 35;
	}
1239417
public function has($key)
    {
        if (!$this->isEnabled()) {
            return false;
        }

        return (false !== apc_fetch($this->prefix() . $key));
    }
375610
protected function validate_key( $key ) {
		$url_parts = Utils\parse_url( $key, -1, false );
		if ( ! empty( $url_parts['scheme'] ) ) { // is url
			$parts   = array( 'misc' );
			$parts[] = $url_parts['scheme'] . '-' . $url_parts['host'] .
				( empty( $url_parts['port'] ) ? '' : '-' . $url_parts['port'] );
			$parts[] = substr( $url_parts['path'], 1 ) .
				( empty( $url_parts['query'] ) ? '' : '-' . $url_parts['query'] );
		} else {
			$key   = str_replace( '\\', '/', $key );
			$parts = explode( '/', ltrim( $key ) );
		}

		$parts = preg_replace( "#[^{$this->whitelist}]#i", '-', $parts );

		return implode( '/', $parts );
	}
1105983
public function has(string $key) : bool
    {
        return isset($this->collection[$this->useKey($key)]);
    }
641473
public function isValid($key = null) {
        if (isset($key)) {
            return empty($this->errors[$key]);
        }
        else {
            return empty($this->errors);
        }
    }