//from https://github.com/mavinoo/laravelBatch
static function batchUpdate($model, array $values, $index = null){
  $final = [];
  $ids = [];
  if (!count($values)) {
    return false;
  }
  if (!isset($index) || empty($index)) {
    $index = $model->getKeyName();
  }
  foreach ($values as $key => $val) {
    $ids[] = $val[$index];
    foreach (array_keys($val) as $field) {
      if ($field !== $index) {
        $value = (is_null($val[$field]) ? 'NULL' : '"' . self::mysql_escape($val[$field]) . '"');
        $final[$field][] = 'WHEN `' . $index . '` = "' . $val[$index] . '" THEN ' . $value . ' ';
      }
    }
  }
  $cases = '';
  foreach ($final as $k => $v) {
    $cases .= '`' . $k . '` = (CASE ' . implode("\n", $v) . "\n"
      . 'ELSE `' . $k . '` END), ';
  }
  $full_table     =  $model->getConnection()->getTablePrefix() . $model->getTable();
  $query = "UPDATE `" .$full_table . "` SET " . substr($cases, 0, -2) . " WHERE `$index` IN(" . '"' . implode('","', $ids) . '"' . ");";
  \DB::update($query);
  #return $this->db->connection($this->getConnectionName($table))->update($query);
}

$userInstance = new User();
$value = [
  [
    'id' => 2,
    'contest_name' => 'A1',
    'project_name' => 'P1'
  ] ,
  [
    'id' => 3,
    'contest_name' => 'A2',
    'project_name' => 'P2'
  ] ,
];
$index = 'id';
Utils::batchUpdate($userInstance, $value, $index);