Merge pull request #787 from ispyisail/fix/removediagram-cascade-delete

Cascade-delete a diagram's element/terminal/conductor rows on removal

sources/dataBase/projectdatabase.cpp

@@ -225,12 +225,57 @@ void projectDataBase::addDiagram(Diagram *diagram)
 
 void projectDataBase::removeDiagram(Diagram *diagram)
 {
-	m_remove_diagram_query.bindValue(":uuid", diagram->uuid().toString());
+	const QString uuid_str = diagram->uuid().toString();
+
+		//Order matters: element_info and terminal are scoped through a
+		//subquery on element, so they must run before element itself is
+		//deleted below. The whole cascade runs in one transaction and is
+		//rolled back on the first error, so a mid-cascade failure (e.g. a
+		//locked DB) can't leave the diagram row deleted while its
+		//element/terminal/element_info/conductor rows survive.
+	m_data_base.transaction();
+
+	m_cascade_remove_element_info_query.bindValue(":uuid", uuid_str);
+	if (!m_cascade_remove_element_info_query.exec()) {
+		qDebug() << "projectDataBase::removeDiagram element_info cascade error : "
+				 << m_cascade_remove_element_info_query.lastError();
+		m_data_base.rollback();
+		return;
+	}
+
+	m_cascade_remove_terminal_query.bindValue(":uuid", uuid_str);
+	if (!m_cascade_remove_terminal_query.exec()) {
+		qDebug() << "projectDataBase::removeDiagram terminal cascade error : "
+				 << m_cascade_remove_terminal_query.lastError();
+		m_data_base.rollback();
+		return;
+	}
+
+	m_cascade_remove_conductor_query.bindValue(":uuid", uuid_str);
+	if (!m_cascade_remove_conductor_query.exec()) {
+		qDebug() << "projectDataBase::removeDiagram conductor cascade error : "
+				 << m_cascade_remove_conductor_query.lastError();
+		m_data_base.rollback();
+		return;
+	}
+
+	m_cascade_remove_element_query.bindValue(":uuid", uuid_str);
+	if (!m_cascade_remove_element_query.exec()) {
+		qDebug() << "projectDataBase::removeDiagram element cascade error : "
+				 << m_cascade_remove_element_query.lastError();
+		m_data_base.rollback();
+		return;
+	}
+
+	m_remove_diagram_query.bindValue(":uuid", uuid_str);
 	if (!m_remove_diagram_query.exec()) {
 		qDebug() << "projectDataBase::removeDiagram delete error : " << m_remove_diagram_query.lastError();
-	} else {
-		emit dataBaseUpdated();
+		m_data_base.rollback();
+		return;
 	}
+
+	m_data_base.commit();
+	emit dataBaseUpdated();
 }
 
 void projectDataBase::diagramInfoChanged(Diagram *diagram)
@@ -772,7 +817,27 @@ void projectDataBase::prepareQuery()
 	m_insert_diagram_query = QSqlQuery(m_data_base);
 	m_insert_diagram_query.prepare("INSERT INTO diagram (uuid, pos) VALUES (:uuid, :pos)");
 
-		//REMOVE DIAGRAM
+		//REMOVE DIAGRAM (cascade first: element_info and terminal have no
+		//diagram_uuid column of their own, so both are scoped through
+		//element while the element rows for this diagram still exist).
+	m_cascade_remove_element_info_query = QSqlQuery(m_data_base);
+	m_cascade_remove_element_info_query.prepare(
+		"DELETE FROM element_info WHERE element_uuid IN "
+		"(SELECT uuid FROM element WHERE diagram_uuid = :uuid)");
+
+	m_cascade_remove_terminal_query = QSqlQuery(m_data_base);
+	m_cascade_remove_terminal_query.prepare(
+		"DELETE FROM terminal WHERE element_uuid IN "
+		"(SELECT uuid FROM element WHERE diagram_uuid = :uuid)");
+
+	m_cascade_remove_conductor_query = QSqlQuery(m_data_base);
+	m_cascade_remove_conductor_query.prepare(
+		"DELETE FROM conductor WHERE diagram_uuid = :uuid");
+
+	m_cascade_remove_element_query = QSqlQuery(m_data_base);
+	m_cascade_remove_element_query.prepare(
+		"DELETE FROM element WHERE diagram_uuid = :uuid");
+
 	m_remove_diagram_query = QSqlQuery(m_data_base);
 	m_remove_diagram_query.prepare("DELETE FROM diagram WHERE uuid=:uuid");
 

sources/dataBase/projectdatabase.h

@@ -106,7 +106,11 @@ class projectDataBase : public QObject
 				  m_insert_terminal_query,
 				  m_insert_conductor_query,
 				  m_update_conductor_query,
-				  m_remove_conductor_query;
+				  m_remove_conductor_query,
+				  m_cascade_remove_element_info_query,
+				  m_cascade_remove_terminal_query,
+				  m_cascade_remove_conductor_query,
+				  m_cascade_remove_element_query;
 
 #ifdef QET_EXPORT_PROJECT_DB
 	public: