Pop-up completion with distinct values

A QSortFilterProxyModel is used for filtering the values in the column so
only distinct values are accepted for the completion. With this change
the less intrusive pop-up completion can be used, displaying only unique
values in the completion menu.

src/ExtendedTableWidget.cpp

@@ -100,6 +100,24 @@ QList<QByteArrayList> parseClipboard(QString clipboard)
 
 }
 
+UniqueFilterModel::UniqueFilterModel(QObject* parent)
+    : QSortFilterProxyModel(parent)
+{
+}
+
+bool UniqueFilterModel::filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const
+{
+    QModelIndex index = sourceModel()->index(sourceRow, filterKeyColumn(), sourceParent);
+    const QString& value = index.data().toString();
+
+    if (!value.isEmpty() && !m_uniqueValues.contains(value)) {
+        const_cast<UniqueFilterModel*>(this)->m_uniqueValues.insert(value);
+        return true;
+    }
+    else
+        return false;
+
+}
 
 ExtendedTableWidgetEditorDelegate::ExtendedTableWidgetEditorDelegate(QObject* parent)
     : QStyledItemDelegate(parent)
@@ -111,10 +129,16 @@ QWidget* ExtendedTableWidgetEditorDelegate::createEditor(QWidget* parent, const
     QLineEdit* editor = new QLineEdit(parent);
     // If the row count is not greater than the complete threshold setting, set a completer of values based on current values in the column.
     if (index.model()->rowCount() <= Settings::getValue("databrowser", "complete_threshold").toInt()) {
-        QCompleter *completer = new QCompleter(editor);
-        completer->setModel(const_cast<QAbstractItemModel*>(index.model()));
+        QCompleter* completer = new QCompleter(editor);
+        UniqueFilterModel* completerFilter = new UniqueFilterModel(completer);
+        // Provide a filter for the source model, so only unique and non-empty values are accepted.
+        completerFilter->setSourceModel(const_cast<QAbstractItemModel*>(index.model()));
+        completerFilter->setFilterKeyColumn(index.column());
+        completer->setModel(completerFilter);
+        // Complete on this column, using a popup and case-insensitively.
         completer->setCompletionColumn(index.column());
-        completer->setCompletionMode(QCompleter::InlineCompletion);
+        completer->setCompletionMode(QCompleter::PopupCompletion);
+        completer->setCaseSensitivity(Qt::CaseInsensitive);
         editor->setCompleter(completer);
     }
     // Set the maximum length to the highest possible value instead of the default 32768.

src/ExtendedTableWidget.h

@@ -6,12 +6,25 @@
 #include <QDropEvent>
 #include <QDragMoveEvent>
 #include <QStyledItemDelegate>
+#include <QSortFilterProxyModel>
 
 class QMenu;
 class QMimeData;
 class FilterTableHeader;
 namespace sqlb { class ObjectIdentifier; }
 
+// Filter proxy model that only accepts distinct non-empty values.
+class UniqueFilterModel : public QSortFilterProxyModel
+{
+    Q_OBJECT
+
+public:
+    explicit UniqueFilterModel(QObject* parent = nullptr);
+    bool filterAcceptsRow(int sourceRow, const QModelIndex &sourceParent) const override;
+ private:
+    QSet<QString> m_uniqueValues;
+};
+
 // We use this class to provide editor widgets for the ExtendedTableWidget. It's used for every cell in the table view.
 class ExtendedTableWidgetEditorDelegate : public QStyledItemDelegate
 {