+ /**
+ * @brief Starts a transaction
+ *
+ * @return boolean Was the command executed successfully?
+ */
+ static public function transaction() {
+ if (!self::e('COMMIT')) {
+ return false;
+ }
+ if (!self::e('START TRANSACTION')) {
+ return false;
+ }
+ self::$in_transaction = true;
+ return true;
+ }
+
+ /**
+ * @brief Does a commit
+ *
+ * @return boolean Was the command executed successfully?
+ */
+ static public function commit() {
+ if (!self::e('COMMIT')) {
+ return false;
+ }
+ self::$in_transaction = false;
+ return true;
+ }
+
+ /**
+ * @brief Does a rollback
+ *
+ * @return boolean Was the command executed successfully?
+ */
+ static public function rollback() {
+ if (!self::e('ROLLBACK')) {
+ return false;
+ }
+ self::$in_transaction = false;
+ return true;
+ }
+
+ /**
+ * @brief Build the array with the table relations
+ *
+ * The array is build from the database definitions in dbstructure.php
+ *
+ * This process must only be started once, since the value is cached.
+ */
+ static private function build_relation_data() {
+ $definition = db_definition();
+
+ foreach ($definition AS $table => $structure) {
+ foreach ($structure['fields'] AS $field => $field_struct) {
+ if (isset($field_struct['relation'])) {
+ foreach ($field_struct['relation'] AS $rel_table => $rel_field) {
+ self::$relation[$rel_table][$rel_field][$table][] = $field;
+ }
+ }
+ }
+ }
+ }
+
+ /**
+ * @brief Delete a row from a table
+ *
+ * @param string $table Table name
+ * @param array $param parameter array
+ * @param boolean $in_process Internal use: Only do a commit after the last delete
+ * @param array $callstack Internal use: prevent endless loops
+ *
+ * @return boolean|array was the delete successfull? When $in_process is set: deletion data
+ */
+ static public function delete($table, $param, $in_process = false, &$callstack = array()) {
+
+ $commands = array();
+
+ // Create a key for the loop prevention
+ $key = $table.':'.implode(':', array_keys($param)).':'.implode(':', $param);
+
+ // We quit when this key already exists in the callstack.
+ if (isset($callstack[$key])) {
+ return $commands;
+ }
+
+ $callstack[$key] = true;
+
+ $table = self::$dbo->escape($table);
+
+ $commands[$key] = array('table' => $table, 'param' => $param);
+
+ // To speed up the whole process we cache the table relations
+ if (count(self::$relation) == 0) {
+ self::build_relation_data();
+ }
+
+ // Is there a relation entry for the table?
+ if (isset(self::$relation[$table])) {
+ // We only allow a simple "one field" relation.
+ $field = array_keys(self::$relation[$table])[0];
+ $rel_def = array_values(self::$relation[$table])[0];
+
+ // Create a key for preventing double queries
+ $qkey = $field.'-'.$table.':'.implode(':', array_keys($param)).':'.implode(':', $param);
+
+ // When the search field is the relation field, we don't need to fetch the rows
+ // This is useful when the leading record is already deleted in the frontend but the rest is done in the backend
+ if ((count($param) == 1) AND ($field == array_keys($param)[0])) {
+ foreach ($rel_def AS $rel_table => $rel_fields) {
+ foreach ($rel_fields AS $rel_field) {
+ $retval = self::delete($rel_table, array($rel_field => array_values($param)[0]), true, $callstack);
+ $commands = array_merge($commands, $retval);
+ }
+ }
+ // We quit when this key already exists in the callstack.
+ } elseif (!isset($callstack[$qkey])) {
+
+ $callstack[$qkey] = true;
+
+ // Fetch all rows that are to be deleted
+ $sql = "SELECT ".self::$dbo->escape($field)." FROM `".$table."` WHERE `".
+ implode("` = ? AND `", array_keys($param))."` = ?";
+
+ $data = self::p($sql, $param);
+ while ($row = self::fetch($data)) {
+ // Now we accumulate the delete commands
+ $retval = self::delete($table, array($field => $row[$field]), true, $callstack);
+ $commands = array_merge($commands, $retval);
+ }
+
+ // Since we had split the delete command we don't need the original command anymore
+ unset($commands[$key]);
+ }
+ }
+
+ if (!$in_process) {
+ // Now we finalize the process
+ $do_transaction = !self::$in_transaction;
+
+ if ($do_transaction) {
+ self::transaction();
+ }
+
+ $compacted = array();
+ $counter = array();
+ foreach ($commands AS $command) {
+ if (count($command['param']) > 1) {
+ $sql = "DELETE FROM `".$command['table']."` WHERE `".
+ implode("` = ? AND `", array_keys($command['param']))."` = ?";
+
+ logger(dba::replace_parameters($sql, $command['param']), LOGGER_DATA);
+
+ if (!self::e($sql, $command['param'])) {
+ if ($do_transaction) {
+ self::rollback();
+ }
+ return false;
+ }
+ } else {
+ $key_table = $command['table'];
+ $key_param = array_keys($command['param'])[0];
+ $value = array_values($command['param'])[0];
+
+ // Split the SQL queries in chunks of 100 values
+ // We do the $i stuff here to make the code better readable
+ $i = $counter[$key_table][$key_param];
+ if (count($compacted[$key_table][$key_param][$i]) > 100) {
+ ++$i;
+ }
+
+ $compacted[$key_table][$key_param][$i][$value] = $value;
+ $counter[$key_table][$key_param] = $i;
+ }
+ }
+ foreach ($compacted AS $table => $values) {
+ foreach ($values AS $field => $field_value_list) {
+ foreach ($field_value_list AS $field_values) {
+ $sql = "DELETE FROM `".$table."` WHERE `".$field."` IN (".
+ substr(str_repeat("?, ", count($field_values)), 0, -2).");";
+
+ logger(dba::replace_parameters($sql, $field_values), LOGGER_DATA);
+
+ if (!self::e($sql, $field_values)) {
+ if ($do_transaction) {
+ self::rollback();
+ }
+ return false;
+ }
+ }
+ }
+ }
+ if ($do_transaction) {
+ self::commit();
+ }
+ return true;
+ }
+
+ return $commands;
+ }
+