Added a QSortFilterProxyModel subclass to enable sorting by different columns in the views.

model/generalsortfiltermodel.cpp

@@ -0,0 +1,42 @@
+#include "generalsortfiltermodel.h"
+#include "metadata.h"
+
+GeneralSortFilterModel::GeneralSortFilterModel(std::shared_ptr<TableModel> sourceModel)
+    : QSortFilterProxyModel{sourceModel.get()}
+    , m_sourceModel(sourceModel) {
+  setSourceModel(sourceModel.get());
+
+  m_collator.setNumericMode(true);
+}
+
+bool GeneralSortFilterModel::lessThan(const QModelIndex& source_left,
+                                      const QModelIndex& source_right) const {
+  if (source_left.column() != source_right.column()) {
+    return false;
+  }
+
+  QAbstractItemModel* localSourceModel = sourceModel();
+  const int role                       = GET_ROLE_FOR_COLUMN(source_left.column());
+  const QVariant leftData              = localSourceModel->data(source_left);
+  const QVariant rightData             = localSourceModel->data(source_right);
+
+  const bool isText = STRING_ROLES.contains(role);
+  if (isText) {
+    const QString leftString  = leftData.toString();
+    const QString rightString = rightData.toString();
+    return m_collator.compare(leftString, rightString) > 0;
+  }
+  const bool isInt = INT_ROLES.contains(role);
+  if (isInt) {
+    const int leftInt  = leftData.toInt();
+    const int rightInt = rightData.toInt();
+    return leftInt > rightInt;
+  }
+  const bool isDouble = DOUBLE_ROLES.contains(role);
+  if (isDouble) {
+    const int leftInt  = leftData.toDouble();
+    const int rightInt = rightData.toDouble();
+    return leftInt > rightInt;
+  }
+  return false;
+}

model/generalsortfiltermodel.h

@@ -0,0 +1,23 @@
+#ifndef GENERALSORTFILTERMODEL_H
+#define GENERALSORTFILTERMODEL_H
+
+#include <QCollator>
+#include <QSortFilterProxyModel>
+
+#include "tablemodel.h"
+
+class GeneralSortFilterModel : public QSortFilterProxyModel {
+  Q_OBJECT
+ public:
+  explicit GeneralSortFilterModel(std::shared_ptr<TableModel> sourceModel = nullptr);
+
+  /// QSortFilterProxyModel interface
+ protected:
+  bool lessThan(const QModelIndex& sourceLeft, const QModelIndex& sourceRight) const override;
+
+ private:
+  std::shared_ptr<TableModel> m_sourceModel;
+  QCollator m_collator;  /// for sorting
+};
+
+#endif  // GENERALSORTFILTERMODEL_H