/**
* Executes the child query and ties the result to the output of the parent query
*
* @param {array} $parentRows Query output of the parent query
* @param {object} $child
*/
private function bindChild(&$parentRows, &$child)
{
$generalErrorMessage = "Cannot nest queries " . $this->name() . " and " . $child->name() . " - ";
// This error should never occur, since the parser constructs the two childs automatically
if (!$child->children || count($child->children) != 2) {
throw new \Exception($generalErrorMessage . "child does not have 2 children");
}
$paramID = $child->defaultParam;
// Fall back in case there is no default param (should not occur anymore)
if (!$paramID) {
// Get parameters of second (last) child of $child.
// Suppose you have "a(b)". This corresponds to parent = "a" and child = "b:a"
// "b:a" has two childs: "b" and "b.a"
// We should get the param of the link-query "b.a" which is the second child of $child
$paramIDs = array_keys(get_object_vars($child->children[1]->params));
// There should be exactly 1 parameter
if (count($paramIDs) != 1) {
throw new \Exception($generalErrorMessage . "link-query " . $child->children[1]->name() . " should have exactly one parameter");
}
$paramID = $paramIDs[0];
}
// Get the parent key which should be matched with the childs parameter
$keyIDs = array_keys(get_object_vars($this->keys));
if (count($keyIDs) != 1) {
throw new \Exception($generalErrorMessage . "parent should have exactly one key");
}
$parentKey = $this->keys->{$keyIDs[0]};
if (!is_array($parentRows)) {
throw new \Exception($generalErrorMessage . "parentRows should be an array of associative arrays");
}
if (count($parentRows) > 0 && !is_array($parentRows[0])) {
throw new \Exception($generalErrorMessage . "parentRows should be an array of associative arrays");
}
if (count($parentRows) > 0 && !array_key_exists($parentKey, $parentRows[0])) {
throw new \Exception($generalErrorMessage . "parentRows should consist of associative arrays containing the field '" . $parentKey . "'");
}
// Take root parameters as default params for child
$params = $this->paramValues;
// Select the child param values from the parent query output
$values = array();
foreach ($parentRows as $row) {
if (!in_array($row[$parentKey], $values)) {
$values[] = $row[$parentKey];
}
}
$params[$paramID] = $values;
// Execute child query and group results; cleanUp can also be done at this point
$childRows = $child->group()->select($params, $paramID, true);
$childFieldName = $child->prefix();
// Combine child rows with parent rows
for ($i = 0; $i < count($parentRows); $i++) {
$keyValue = $parentRows[$i][$parentKey];
$parentRows[$i][$childFieldName] = array_key_exists($keyValue, $childRows) ? $childRows[$keyValue] : array();
}
}
