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<?php |
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namespace mindplay\sql\framework; |
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use Iterator; |
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use IteratorAggregate; |
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use RuntimeException; |
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/** |
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* This class represents the result of fetching a `PreparedStatement`, e.g. the results of |
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* a `SELECT` SQL query, and with Mappers being applied on-the-fly, in batches. |
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* |
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* It implements `IteratorAggregate`, allowing you to execute the query and iterate |
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* over the result set with a `foreach` statement. |
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*/ |
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class Result implements IteratorAggregate |
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{ |
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/** |
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* @var PreparedStatement |
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*/ |
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private $statement; |
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/** |
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* @var int |
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*/ |
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private $batch_size; |
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/** |
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* @var Mapper[] list of Mappers to apply when fetching results |
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*/ |
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private $mappers; |
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/** |
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* @var Indexer|null |
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*/ |
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private $indexer; |
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/** |
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* @param PreparedStatement $statement prepared statement |
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* @param int $batch_size batch-size (when fetching large result sets) |
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* @param Mapper[] $mappers list of Mappers to apply while fetching results |
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* @param Indexer|null $indexer optional Indexer (used to customize Generator keys) |
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*/ |
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public function __construct(PreparedStatement $statement, $batch_size, array $mappers, Indexer $indexer = null) |
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{ |
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$this->statement = $statement; |
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$this->batch_size = $batch_size; |
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$this->mappers = $mappers; |
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$this->indexer = $indexer; |
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} |
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/** |
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* @return mixed|null first record of the record-set (or NULL, if the record-set is empty) |
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*/ |
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public function firstRow() |
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{ |
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foreach ($this->createIterator(1) as $record) { |
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return $record; // break from loop immediately after fetching the first record |
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} |
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return null; |
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} |
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/** |
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* @return mixed|null first column value of the first record of the record-set (or NULL, if the record-set is empty) |
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*/ |
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public function firstCol() |
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{ |
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foreach ($this->createIterator(1) as $record) { |
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$keys = array_keys($record); |
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return $record[$keys[0]]; // break from loop immediately after fetching the first record |
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} |
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return null; |
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} |
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/** |
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* @return array all the records of the record-set |
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*/ |
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public function all() |
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{ |
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return iterator_to_array($this->getIterator()); |
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} |
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/** |
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* Execute this Statement and return a Generator, so you can iterate over the results. |
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* |
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* This method implements `IteratorAggregate`, permitting you to iterate directly over |
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* the resulting records (or objects) without explicitly having to call this method. |
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* |
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* @return Iterator |
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*/ |
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public function getIterator() |
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{ |
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return $this->createIterator($this->batch_size); |
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} |
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/** |
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* Create an Iterator with a given batch-size. |
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* |
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* @param int $batch_size batch-size when processing the result set |
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* |
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* @return Iterator |
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*/ |
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private function createIterator($batch_size) |
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{ |
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$fetching = true; |
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do { |
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// fetch a batch of records: |
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$batch = []; |
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do { |
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$record = $this->statement->fetch(); |
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if ($record) { |
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$batch[] = $record; |
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} else { |
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if (count($batch) === 0) { |
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return; // last batch of records fetched |
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} |
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$fetching = false; // last record of batch fetched |
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} |
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} while ($fetching && (count($batch) < $batch_size)); |
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// apply Mappers to current batch of records: |
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$num_records = count($batch); |
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foreach ($this->mappers as $index => $mapper) { |
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$batch = $mapper->map($batch); |
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if (count($batch) !== $num_records) { |
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$count = count($batch); |
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throw new RuntimeException("Mapper #{$index} returned {$count} records, expected: {$num_records}"); |
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} |
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} |
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// return each record from the current batch: |
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if ($this->indexer) { |
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foreach ($batch as $record) { |
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$index = $this->indexer->index($record); |
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yield $index => $record; |
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} |
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} else { |
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foreach ($batch as $record) { |
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yield $record; |
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} |
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} |
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} while ($fetching); |
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} |
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} |
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mindplay-dk /
sql
This check marks implicit conversions of arrays to boolean values in a comparison. While in PHP an empty array is considered to be equal (but not identical) to false, this is not always apparent.
Consider making the comparison explicit by using
empty(..)or! empty(...)instead.