/**
* Retrieves a value from cache with a specified key.
* This method should be implemented by child classes to retrieve the data
* from specific cache storage.
* @param string $key a unique key identifying the cached value
* @return string|boolean the value stored in cache, false if the value is not in the cache or expired.
*/
protected function getValue($key)
{
$query = new Query();
$row = $query->select(['data'])->from($this->cacheCollection)->where(['id' => $key, '$or' => [['expire' => 0], ['expire' => ['$gt' => time()]]]])->one($this->db);
if (empty($row)) {
return false;
} else {
return $row['data'];
}
}
/**
* Ensures migration history contains at least base migration entry.
*/
protected function ensureBaseMigrationHistory()
{
if (!$this->baseMigrationEnsured) {
$query = new Query();
$row = $query->select(['version'])->from($this->migrationCollection)->andWhere(['version' => self::BASE_MIGRATION])->limit(1)->one($this->db);
if (empty($row)) {
$this->addMigrationHistory(self::BASE_MIGRATION);
}
$this->baseMigrationEnsured = true;
}
}