Save a symbol's links from the project database

A symbol's <links_uuids> are now what the project database's link rows
list for it, in their order (projectDataBase::savedLinks()), instead of
a list the save built itself from the symbol's partners: QETZ-DB-FIRST
stage 2a, the save reads links from the database. A symbol the database
does not hold (saved outside a project) still lists them itself.

The rows leave out a partner the project no longer has, so removing a
folio with every folio built no longer saves links to its symbols, as
lazy folios already did (the links part of F113). Every other save is
unchanged.

tst_resaveunchanged removedFolioLeavesNoLinkToIt: affuteuse_250h with
every folio built, folio 3 removed: 4 links named symbols no longer in
the file, none now.

Needs #1522 (each symbol its own uuid) and #1523 (rows in saved order);
local only until both are merged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XCdg2Er2vYhB8Vwa5G7fSR

sources/dataBase/projectdatabase.cpp

@@ -3954,6 +3954,39 @@ QStringList projectDataBase::linkRowMismatches()
 	return mismatches;
 }
 
+/**
+	@brief projectDataBase::savedLinks
+	The links @p element saves, read from its link rows, in their order
+	(insertLinkRows()): what Element::toXml() writes (QETZ-DB-FIRST stage
+	2a). A partner the project no longer has, on a removed folio, has no
+	row, so it is not saved.
+	@return false if the database does not hold @p element (not placed in
+	this project): the caller then takes the links from the symbol itself
+*/
+bool projectDataBase::savedLinks(const Element *element, QList<std::pair<QUuid, int>> *links)
+{
+	if (!element || !m_placed_elements.contains(element->uuid(), const_cast<Element *>(element))) {
+		return false;
+	}
+	flushLinks();
+	if (m_saved_links_query.lastQuery().isEmpty()) {
+		m_saved_links_query = QSqlQuery(m_data_base);
+		m_saved_links_query.prepare(QStringLiteral("SELECT linked_uuid, group_index FROM link "
+												   "WHERE element_uuid = :uuid ORDER BY ord, rowid"));
+	}
+	m_saved_links_query.bindValue(QStringLiteral(":uuid"), element->uuid().toString());
+	if (!m_saved_links_query.exec()) {
+		qDebug() << "projectDataBase::savedLinks error : " << m_saved_links_query.lastError();
+		return false;
+	}
+	links->clear();
+	while (m_saved_links_query.next()) {
+		links->append({QUuid(m_saved_links_query.value(0).toString()),
+					   m_saved_links_query.value(1).isNull() ? -1 : m_saved_links_query.value(1).toInt()});
+	}
+	return true;
+}
+
 /**
 	@brief projectDataBase::waitingSymbols
 	@return the symbols on folios not built yet (lazy folios): partners a

sources/dataBase/projectdatabase.h

@@ -155,6 +155,7 @@ class projectDataBase : public QObject
 		void conductorUuidChanged(Conductor *conductor, const QUuid &old_uuid);
 		QStringList conductorPropertiesMismatches() const;
 		QStringList linkRowMismatches();
+		bool savedLinks(const Element *element, QList<std::pair<QUuid, int>> *links);
 
 			//Fill the three stores from a project's document before its
 			//folios are built, then, once
@@ -330,6 +331,7 @@ class projectDataBase : public QObject
 			//written: a link is made first and its contact group set after,
 			//so the rows are written when next read, as drawing items are.
 		QList<QPointer<Element>> m_dirty_link_elements;
+		QSqlQuery m_saved_links_query;
 			//Elements moved since their folio cell was last written: a move
 			//sends xChanged and yChanged for every step of a drag, so the
 			//cell is written when next read, as drawing items are.

sources/qetgraphicsitem/element.cpp

@@ -1436,12 +1436,19 @@ QDomElement Element::toXml(
 	QDomElement inputs = document.createElement(QStringLiteral("inputs"));
 	element.appendChild(inputs);
 
-	//if this element is linked to other elements,
-	//save the uuid of each other elements (linksToSave())
+	//if this element is linked to other elements, save the uuid of each:
+	//as the project database's link rows list them (QETZ-DB-FIRST stage
+	//2a), or, for a symbol the database does not hold, as it lists them
+	//itself (linksToSave())
 	QList<std::pair<QUuid, int>> links;
-	for (const SavedLink &link : linksToSave(diagram() && diagram()->project()
-											 ? diagram()->project()->waitingLinkTargets() : QSet<QUuid>()))
-		links.append({link.uuid, link.group_index});
+	projectDataBase *database = diagram() && diagram()->project()
+			? diagram()->project()->dataBase() : nullptr;
+	if (!database || !database->savedLinks(this, &links)) {
+		links.clear();
+		for (const SavedLink &link : linksToSave(diagram() && diagram()->project()
+												 ? diagram()->project()->waitingLinkTargets() : QSet<QUuid>()))
+			links.append({link.uuid, link.group_index});
+	}
 	if (!links.isEmpty()) {
 		QDomElement links_uuids = document.createElement(QStringLiteral("links_uuids"));
 		for (const auto &link : std::as_const(links)) {

tests/qttest/tst_resaveunchanged.cpp

@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 #include <QtTest>
+#include <QSet>
 
 #include <QDir>
 #include <QFile>
@@ -481,6 +482,46 @@ private slots:
 		QVERIFY2(out.contains(QStringLiteral("link rows: 0 differ")), qPrintable(out.right(600)));
 	}
 
+	// Removing a folio with every folio built saves no link to its symbols:
+	// the save takes each symbol's links from the project database, which
+	// drops a partner the project no longer has (F113; lazy folios already
+	// saved it so). affuteuse_250h, folio 3 removed: its coil KA1 is linked
+	// to contacts on other folios.
+	void removedFolioLeavesNoLinkToIt()
+	{
+#ifndef QET_HAS_SCRIPTING
+		QSKIP("needs --run: this QElectroTech is built without Qt Qml");
+#endif
+		const QString saved = m_dir.filePath(QStringLiteral("removed%1.qet").arg(m_run));
+		const QString js = m_dir.filePath(QStringLiteral("removed%1.js").arg(m_run));
+		QFile script(js);
+		QVERIFY(script.open(QIODevice::WriteOnly));
+		script.write(QStringLiteral(
+			"qet.log('REMOVED ' + qet.removeFolio(3));\n"
+			"qet.save('%1');\n").arg(saved).toUtf8());
+		script.close();
+		const QString out = runChecked({QStringLiteral("--run"), js,
+										QStringLiteral(QET_EXAMPLES_DIR "/affuteuse_250h.qet")}, true);
+		QVERIFY2(out.contains(QStringLiteral("REMOVED true")), qPrintable(out.right(600)));
+
+		QFile file(saved);
+		QVERIFY(file.open(QIODevice::ReadOnly));
+		const QString text = QString::fromUtf8(file.readAll());
+			//Placed symbols carry a uuid; symbol definitions in the
+			//collection do not
+		QSet<QString> symbols;
+		auto it = QRegularExpression(QStringLiteral("<element [^>]*\\buuid=\"(\\{[0-9a-f-]+\\})\"")).globalMatch(text);
+		while (it.hasNext()) symbols.insert(it.next().captured(1));
+		QList<QString> links;
+		auto lt = QRegularExpression(QStringLiteral("<link_uuid [^>]*\\buuid=\"(\\{[0-9a-f-]+\\})\"")).globalMatch(text);
+		while (lt.hasNext()) links << lt.next().captured(1);
+		QVERIFY(!symbols.isEmpty() && !links.isEmpty());
+		int dangling = 0;
+		for (const QString &link : std::as_const(links))
+			if (!symbols.contains(link)) ++dangling;
+		QCOMPARE(dangling, 0);
+	}
+
 	// The stores filled from the document before the folios are built
 	// hold what building them gives, for a
 	// project saved by this version (every symbol, folio and wire carries