`Laminas\Db\Adapter\Driver\Pdo\Result#rewind()` can cause data loss by always reading row from database
Grundik opened this issue · 3 comments
Bug Report
| Q | A |
|---|---|
| Version(s) | any since at least 2.0.0 |
Summary
Laminas\Db\Adapter\Driver\Pdo\Result->rewind() always reading one row from the database, even if its already read. That could lead to data loss, if ->rewind() called multiple times somehow.
Current behavior
Laminas\Db\Adapter\Driver\Pdo\Result->rewind() unconditionally reading one row:
$this->currentData = $this->resource->fetch(\PDO::FETCH_ASSOC);
$this->currentComplete = true;
$this->position = 0;(see https://github.com/laminas/laminas-db/blob/2.13.x/src/Adapter/Driver/Pdo/Result.php#L196)
How to reproduce
// make any query to database, resulting $result object
$result->rewind();
$result->rewind();
$data = $result->current(); // that would contain second readed row (if any). First one is lost.
$position = $result->key(); // that would return 0, not 1 as it is in factExpected behavior
Calling ->rewind() multiple times should not cause data loss. Method should make use of $this->currentComplete flag, and not fetch data if that already done, something like:
if (!$this->currentComplete) {
$this->currentData = $this->resource->fetch(\PDO::FETCH_ASSOC);
$this->currentComplete = true;
}
$this->position = 0;Thanks for reporting this, and for looking into the source code for the cause. I'll write a reproduction test case and then fix. I've got work-related time constraints, but I'll get to it as soon as I can.