QSqlRelationalTableModel: properly clear relational dictionary

When the relationModel is updated (e.g. a new row is added or removed),
the internal relation cache needs a refresh to reflect those changes.

Fixes: QTBUG-128434
Change-Id: Ie388c01d545564ad7b1424d70267166ac1e4bfd6
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>
(cherry picked from commit 48753a03de7c9c394fbf4cf69e2c2f3d1048c85f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

src/sql/models/qsqlrelationaltablemodel.cpp

@@ -105,7 +105,7 @@ struct QRelation
     public:
         Q_DISABLE_COPY(QRelation)   // QRelatedTableModel stores a pointer to this class
         QRelation() = default;
-        void init(QSqlRelationalTableModel *parent, const QSqlRelation &relation);
+        void init(QSqlRelationalTableModel *parent, const QSqlRelation &relation, int column);
 
         void populateModel();
 
@@ -122,6 +122,7 @@ struct QRelation
 
     private:
         QSqlRelationalTableModel *m_parent = nullptr;
+        int col = -1;
         bool m_dictInitialized = false;
 };
 
@@ -139,11 +140,12 @@ private:
     Note: population of the model and dictionary are kept separate
           from initialization, and are populated on an as needed basis.
 */
-void QRelation::init(QSqlRelationalTableModel *parent, const QSqlRelation &relation)
+void QRelation::init(QSqlRelationalTableModel *parent, const QSqlRelation &relation, int column)
 {
     Q_ASSERT(parent != nullptr);
     m_parent = parent;
     rel = relation;
+    col = column;
 }
 
 void QRelation::populateModel()
@@ -156,6 +158,19 @@ void QRelation::populateModel()
         model = new QRelatedTableModel(this, m_parent, m_parent->database());
         model->setTable(rel.tableName());
         model->select();
+        QObject::connect(model, &QAbstractItemModel::dataChanged, model, [&](const QModelIndex &tl, const QModelIndex &br)
+        {
+            if (tl.column() >= col && br.column() <= col)
+                clearDictionary();
+        });
+        QObject::connect(model, &QAbstractItemModel::rowsRemoved, model, [&]()
+        {
+            clearDictionary();
+        });
+        QObject::connect(model, &QAbstractItemModel::rowsInserted, model, [&]()
+        {
+            clearDictionary();
+        });
     }
 }
 
@@ -477,7 +492,7 @@ void QSqlRelationalTableModel::setRelation(int column, const QSqlRelation &relat
         for (auto i = oldSize; i < d->relations.size(); ++i)
             d->relations[i] = QSharedPointer<QRelation>::create();
     }
-    d->relations.at(column)->init(this, relation);
+    d->relations.at(column)->init(this, relation, column);
 }
 
 /*!

tests/auto/sql/models/qsqlrelationaltablemodel/tst_qsqlrelationaltablemodel.cpp

@@ -456,6 +456,29 @@ void tst_QSqlRelationalTableModel::insertRecord()
     model.setSort(0, Qt::AscendingOrder);
     QVERIFY_SQL(model, select());
 
+    constexpr auto fkTitleKey = 4711;
+    constexpr auto fkTitleVal = "new title";
+    {
+        auto relModel = model.relationModel(2);
+        // make sure populateDictionary() is called
+        relModel->select();
+
+        QSqlRecord rec;
+        QSqlField f1("id", QMetaType(QMetaType::Int));
+        QSqlField f2("title", QMetaType(QMetaType::QString));
+
+        f1.setValue(fkTitleKey);
+        f2.setValue(fkTitleVal);
+
+        f1.setGenerated(true);
+        f2.setGenerated(true);
+
+        rec.append(f1);
+        rec.append(f2);
+
+        QVERIFY(relModel->insertRecord(-1, rec));
+    }
+
     QSqlRecord rec;
     QSqlField f1("id", QMetaType(QMetaType::Int));
     QSqlField f2("name", QMetaType(QMetaType::QString));
@@ -464,7 +487,7 @@ void tst_QSqlRelationalTableModel::insertRecord()
 
     f1.setValue(7);
     f2.setValue("test");
-    f3.setValue(1);
+    f3.setValue(fkTitleKey);
     f4.setValue(2);
 
     f1.setGenerated(true);
@@ -481,7 +504,7 @@ void tst_QSqlRelationalTableModel::insertRecord()
 
     QCOMPARE(model.data(model.index(4, 0)).toInt(), 7);
     QCOMPARE(model.data(model.index(4, 1)).toString(), QString("test"));
-    QCOMPARE(model.data(model.index(4, 2)).toString(), QString("herr"));
+    QCOMPARE(model.data(model.index(4, 2)).toString(), QString(fkTitleVal));
 
     // In LeftJoin mode, two additional rows are fetched
     model.setJoinMode(QSqlRelationalTableModel::LeftJoin);
@@ -489,7 +512,7 @@ void tst_QSqlRelationalTableModel::insertRecord()
 
     QCOMPARE(model.data(model.index(6, 0)).toInt(), 7);
     QCOMPARE(model.data(model.index(6, 1)).toString(), QString("test"));
-    QCOMPARE(model.data(model.index(6, 2)).toString(), QString("herr"));
+    QCOMPARE(model.data(model.index(6, 2)).toString(), QString(fkTitleVal));
 }
 
 void tst_QSqlRelationalTableModel::setRecord()