/**
* Implementation of MigrateSource::performRewind().
*
* We could simply execute the query and be functionally correct, but
* we will take advantage of the PDO-based API to optimize the query up-front.
*/
protected function initializeIterator()
{
$this->prepareQuery();
$high_water_property = $this->migration->get('highWaterProperty');
// Get the key values, for potential use in joining to the map table.
$keys = array();
// The rules for determining what conditions to add to the query are as
// follows (applying first applicable rule)
// 1. If the map is joinable, join it. We will want to accept all rows
// which are either not in the map, or marked in the map as NEEDS_UPDATE.
// Note that if high water fields are in play, we want to accept all rows
// above the high water mark in addition to those selected by the map
// conditions, so we need to OR them together (but AND with any existing
// conditions in the query). So, ultimately the SQL condition will look
// like (original conditions) AND (map IS NULL OR map needs update
// OR above high water).
$conditions = $this->query->orConditionGroup();
$condition_added = FALSE;
if (empty($this->configuration['ignore_map']) && $this->mapJoinable()) {
// Build the join to the map table. Because the source key could have
// multiple fields, we need to build things up.
$count = 1;
$map_join = '';
$delimiter = '';
foreach ($this->getIds() as $field_name => $field_schema) {
if (isset($field_schema['alias'])) {
$field_name = $field_schema['alias'] . '.' . $field_name;
}
$map_join .= "{$delimiter}{$field_name} = map.sourceid" . $count++;
$delimiter = ' AND ';
}
$alias = $this->query->leftJoin($this->migration->getIdMap()->getQualifiedMapTableName(), 'map', $map_join);
$conditions->isNull($alias . '.sourceid1');
$conditions->condition($alias . '.source_row_status', MigrateIdMapInterface::STATUS_NEEDS_UPDATE);
$condition_added = TRUE;
// And as long as we have the map table, add its data to the row.
$n = count($this->getIds());
for ($count = 1; $count <= $n; $count++) {
$map_key = 'sourceid' . $count;
$this->query->addField($alias, $map_key, "migrate_map_{$map_key}");
}
if ($n = count($this->migration->get('destinationIds'))) {
for ($count = 1; $count <= $n; $count++) {
$map_key = 'destid' . $count++;
$this->query->addField($alias, $map_key, "migrate_map_{$map_key}");
}
}
$this->query->addField($alias, 'source_row_status', 'migrate_map_source_row_status');
}
// 2. If we are using high water marks, also include rows above the mark.
// But, include all rows if the high water mark is not set.
if (isset($high_water_property['name']) && ($high_water = $this->migration->getHighWater()) !== '') {
if (isset($high_water_property['alias'])) {
$high_water = $high_water_property['alias'] . '.' . $high_water_property['name'];
} else {
$high_water = $high_water_property['name'];
}
$conditions->condition($high_water, $high_water, '>');
$condition_added = TRUE;
}
if ($condition_added) {
$this->query->condition($conditions);
}
return new \IteratorIterator($this->query->execute());
}
