Catch mouse click on dummy row for QTabelView (returned by proxy but not in real model)

Mark81 · 25 Nov 2024, 13:10

Here I learnt how to provide an extra "dummy" row to a QTableView widget.
The goal is to provide a simple way to add a new record. I write here the code snippet reported in that thread:

class AddIdentityProxyModel : public QIdentityProxyModel
{
public:
    AddIdentityProxyModel(QObject *parent = 0): QIdentityProxyModel(parent)
    {
    }

    int rowCount(const QModelIndex &parent = QModelIndex()) const
    {
        return sourceModel()->rowCount() + 1;
    }
};

QSqlTableModel *_model;
QSortFilterProxyModel *_proxyModel;
AddIdentityProxyModel *_addProxy;

QSqlDatabase db = QSqlDatabase::database("mydb");
_model = new QSqlTableModel(this, db);
_model->setTable("mytable");
_model->setEditStrategy(QSqlTableModel::OnRowChange);
_model->select();

_proxyModel = new QSortFilterProxyModel(this);
_proxyModel->setSourceModel(_model);
_proxyModel->sort(1);

_addProxy = new AddIdentityProxyModel(this);
_addProxy->setSourceModel(_proxyModel);

ui->table->setModel(_addProxy);

The solution almost work, but I'm not able to catch clicks on that extra row to actually add a new editable record.
I tried to retrieve the current index when the user click on the table, but:

the onClick signal for QTableView does not fire if the row is not in the actual model
the customContextMenuRequested signal fires but returns an invalid index

Is there a way to catch a click (and of course get focus) on such a dummy row?

JonB · 25 Nov 2024, 14:30

@Mark81
At a guess: although your proxy now returns an extra row its passthrough data() won't see any data there in the source model and I don't know how that might play with the table view. You may have to override data() and do something about that.

Alternatively you may have to handle clicks/context menu at perhaps the QTableView level.

There is also https://stackoverflow.com/questions/53279058/qtableview-how-to-add-a-blank-row-at-the-bottom-and-have-it-show-delegates, I don't know if that helps. Or https://python-forum.io/thread-38353.html. And a slightly different way might be to have an "Add new row" button/link, below the table view: when user clicks it code adds a new, blank row into the SQL model for editing. Or don't do new row by editing in-table-view, use QDataWidgetMapper. These are just thoughts.

Mark81 · 25 Nov 2024, 14:40

@JonB I tried to reimplement data():

QVariant QAbstractItemModel::data(const QModelIndex &index, int role = Qt::DisplayRole) const
{
    if (index.row() == sourceModel->rowCount()) return QVariant("foo");
    return sourceModel->data(index, role);
}

but nothing has changed.
In my question I've already written I tried also to catch the click/context menu at QTableView level but they don't fire or don't have a valid index in that dummy row.

Now I'm trying this library that should do exactly what I'm looking for. But unfortunately I'm not able to use it properly, see this.

JonB · M Mark81 25 Nov 2024, 14:30

@Mark81 said in Catch mouse click on dummy row for QTabelView (returned by proxy but not in real model):

But unfortunately I'm not able to use it properly, see this.

That link, https://github.com/VSRonin/QtModelUtilities/issues/62, gives a 404...

@VRonin used to come here regularly, not often now, he might get pinged by this mention. His code is usually very good, I don't know what the issue is, maybe you can look at the code and figure/workaround.

Mark81 · 25 Nov 2024, 16:16

I double checked the link and it is correct but I cannot open the link too. Odd.
Anyway, you can find the last issue with the subject "Commit create a new row but does not store to the database #62".

Pl45m4 · 25 Nov 2024, 16:52

@Mark81 said in Catch mouse click on dummy row for QTabelView (returned by proxy but not in real model):

Anyway, you can find the last issue with the subject "Commit create a new row but does not store to the database #62".

I've checked the repo manually and I can confirm that there is no such entry in "issues" (what @JonB said).
I see 31 open issues and 30 closed ones.
There is no Issue #62

DBoosalis · wrote on 25 Nov 2024, 16:48

Not sure exactly what the issue is so apologies if off the mark here.
I think you need to capture the item clicked signal in your proxy model and then in the proxy model do this:
QSortFilterProxyModel Class
The QSortFilterProxyModel class provides support for sorting and filtering data passed between another model and a view. More...

Header: #include <QSortFilterProxyModel>
CMake: find_package(Qt6 REQUIRED COMPONENTS Core)
target_link_libraries(mytarget PRIVATE Qt6::Core)
qmake: QT += core
Inherits: QAbstractProxyModel
List of all members, including inherited members
Properties
(since 6.0) autoAcceptChildRows : bool
dynamicSortFilter : bool
filterCaseSensitivity : Qt::CaseSensitivity
filterKeyColumn : int
filterRegularExpression : QRegularExpression
filterRole : int
isSortLocaleAware : bool
recursiveFilteringEnabled : bool
sortCaseSensitivity : Qt::CaseSensitivity
sortRole : int
Public Functions
QSortFilterProxyModel(QObject *parent = nullptr)
virtual ~QSortFilterProxyModel()
bool autoAcceptChildRows() const
QBindable<bool> bindableAutoAcceptChildRows()
QBindable<bool> bindableDynamicSortFilter()
QBindableQt::CaseSensitivity bindableFilterCaseSensitivity()
QBindable<int> bindableFilterKeyColumn()
QBindable<QRegularExpression> bindableFilterRegularExpression()
QBindable<int> bindableFilterRole()
QBindable<bool> bindableIsSortLocaleAware()
QBindable<bool> bindableRecursiveFilteringEnabled()
QBindableQt::CaseSensitivity bindableSortCaseSensitivity()
QBindable<int> bindableSortRole()
bool dynamicSortFilter() const
Qt::CaseSensitivity filterCaseSensitivity() const
int filterKeyColumn() const
QRegularExpression filterRegularExpression() const
int filterRole() const
bool isRecursiveFilteringEnabled() const
bool isSortLocaleAware() const
void setAutoAcceptChildRows(bool accept)
void setDynamicSortFilter(bool enable)
void setFilterCaseSensitivity(Qt::CaseSensitivity cs)
void setFilterKeyColumn(int column)
void setFilterRole(int role)
void setRecursiveFilteringEnabled(bool recursive)
void setSortCaseSensitivity(Qt::CaseSensitivity cs)
void setSortLocaleAware(bool on)
void setSortRole(int role)
Qt::CaseSensitivity sortCaseSensitivity() const
int sortColumn() const
Qt::SortOrder sortOrder() const
int sortRole() const
Reimplemented Public Functions
virtual QModelIndex buddy(const QModelIndex &index) const override
virtual bool canFetchMore(const QModelIndex &parent) const override
virtual int columnCount(const QModelIndex &parent = QModelIndex()) const override
virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override
virtual bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) override
virtual void fetchMore(const QModelIndex &parent) override
virtual Qt::ItemFlags flags(const QModelIndex &index) const override
virtual bool hasChildren(const QModelIndex &parent = QModelIndex()) const override
virtual QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override
virtual QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override
virtual bool insertColumns(int column, int count, const QModelIndex &parent = QModelIndex()) override
virtual bool insertRows(int row, int count, const QModelIndex &parent = QModelIndex()) override
virtual QModelIndex mapFromSource(const QModelIndex &sourceIndex) const override
virtual QItemSelection mapSelectionFromSource(const QItemSelection &sourceSelection) const override
virtual QItemSelection mapSelectionToSource(const QItemSelection &proxySelection) const override
virtual QModelIndex mapToSource(const QModelIndex &proxyIndex) const override
virtual QModelIndexList match(const QModelIndex &start, int role, const QVariant &value, int hits = 1, Qt::MatchFlags flags = Qt::MatchFlags(Qt::MatchStartsWith|Qt::MatchWrap)) const override
virtual QMimeData * mimeData(const QModelIndexList &indexes) const override
virtual QStringList mimeTypes() const override
virtual QModelIndex parent(const QModelIndex &child) const override
virtual bool removeColumns(int column, int count, const QModelIndex &parent = QModelIndex()) override
virtual bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex()) override
virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override
virtual bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override
virtual bool setHeaderData(int section, Qt::Orientation orientation, const QVariant &value, int role = Qt::EditRole) override
virtual void setSourceModel(QAbstractItemModel *sourceModel) override
virtual QModelIndex sibling(int row, int column, const QModelIndex &idx) const override
virtual void sort(int column, Qt::SortOrder order = Qt::AscendingOrder) override
virtual QSize span(const QModelIndex &index) const override
virtual Qt::DropActions supportedDropActions() const override
Public Slots
void invalidate()
void setFilterFixedString(const QString &pattern)
void setFilterRegularExpression(const QString &pattern)
void setFilterRegularExpression(const QRegularExpression &regularExpression)
void setFilterWildcard(const QString &pattern)
Signals
(since 6.0) void autoAcceptChildRowsChanged(bool autoAcceptChildRows)
void filterCaseSensitivityChanged(Qt::CaseSensitivity filterCaseSensitivity)
void filterRoleChanged(int filterRole)
void recursiveFilteringEnabledChanged(bool recursiveFilteringEnabled)
void sortCaseSensitivityChanged(Qt::CaseSensitivity sortCaseSensitivity)
void sortLocaleAwareChanged(bool sortLocaleAware)
void sortRoleChanged(int sortRole)
Protected Functions
virtual bool filterAcceptsColumn(int source_column, const QModelIndex &source_parent) const
virtual bool filterAcceptsRow(int source_row, const QModelIndex &source_parent) const
(since 6.0) void invalidateColumnsFilter()
void invalidateFilter()
(since 6.0) void invalidateRowsFilter()
virtual bool lessThan(const QModelIndex &source_left, const QModelIndex &source_right) const
Detailed Description
QSortFilterProxyModel can be used for sorting items, filtering out items, or both. The model transforms the structure of a source model by mapping the model indexes it supplies to new indexes, corresponding to different locations, for views to use. This approach allows a given source model to be restructured as far as views are concerned without requiring any transformations on the underlying data, and without duplicating the data in memory.

Let's assume that we want to sort and filter the items provided by a custom model. The code to set up the model and the view, without sorting and filtering, would look like this:

    QTreeView *treeView = new QTreeView;
    MyItemModel *model = new MyItemModel(this);

    treeView->setModel(model);

To add sorting and filtering support to MyItemModel, we need to create a QSortFilterProxyModel, call setSourceModel() with the MyItemModel as argument, and install the QSortFilterProxyModel on the view:

    QTreeView *treeView = new QTreeView;
    MyItemModel *sourceModel = new MyItemModel(this);
    QSortFilterProxyModel *proxyModel = new QSortFilterProxyModel(this);

    proxyModel->setSourceModel(sourceModel);
    treeView->setModel(proxyModel);

At this point, neither sorting nor filtering is enabled; the original data is displayed in the view. Any changes made through the QSortFilterProxyModel are applied to the original model.

The QSortFilterProxyModel acts as a wrapper for the original model. If you need to convert source QModelIndexes to sorted/filtered model indexes or vice versa, use mapToSource(), mapFromSource(), mapSelectionToSource(), and mapSelectionFromSource().

Note: By default, the model dynamically re-sorts and re-filters data whenever the original model changes. This behavior can be changed by setting the dynamicSortFilter property.

The Basic Sort/Filter Model and Custom Sort/Filter Model examples illustrate how to use QSortFilterProxyModel to perform basic sorting and filtering and how to subclass it to implement custom behavior.

Sorting
QTableView and QTreeView have a sortingEnabled property that controls whether the user can sort the view by clicking the view's horizontal header. For example:

    treeView->setSortingEnabled(true);

When this feature is on (the default is off), clicking on a header section sorts the items according to that column. By clicking repeatedly, the user can alternate between ascending and descending order.

A sorted QTreeView

Behind the scene, the view calls the sort() virtual function on the model to reorder the data in the model. To make your data sortable, you can either implement sort() in your model, or use a QSortFilterProxyModel to wrap your model – QSortFilterProxyModel provides a generic sort() reimplementation that operates on the sortRole() (Qt::DisplayRole by default) of the items and that understands several data types, including int, QString, and QDateTime. For hierarchical models, sorting is applied recursively to all child items. String comparisons are case sensitive by default; this can be changed by setting the sortCaseSensitivity property.

Custom sorting behavior is achieved by subclassing QSortFilterProxyModel and reimplementing lessThan(), which is used to compare items. For example:

bool MySortFilterProxyModel::lessThan(const QModelIndex &left,
const QModelIndex &right) const
{
QVariant leftData = sourceModel()->data(left);
QVariant rightData = sourceModel()->data(right);

if (leftData.userType() == QMetaType::QDateTime) {
    return leftData.toDateTime() < rightData.toDateTime();
} else {
    static const QRegularExpression emailPattern("[\\w\\.]*@[\\w\\.]*");

    QString leftString = leftData.toString();
    if (left.column() == 1) {
        const QRegularExpressionMatch match = emailPattern.match(leftString);
        if (match.hasMatch())
            leftString = match.captured(0);
    }
    QString rightString = rightData.toString();
    if (right.column() == 1) {
        const QRegularExpressionMatch match = emailPattern.match(rightString);
        if (match.hasMatch())
            rightString = match.captured(0);
    }

    return QString::localeAwareCompare(leftString, rightString) < 0;
}

}

(This code snippet comes from the Custom Sort/Filter Model example.)

An alternative approach to sorting is to disable sorting on the view and to impose a certain order to the user. This is done by explicitly calling sort() with the desired column and order as arguments on the QSortFilterProxyModel (or on the original model if it implements sort()). For example:

    proxyModel->sort(2, Qt::AscendingOrder);

QSortFilterProxyModel can be sorted by column -1, in which case it returns to the sort order of the underlying source model.

Note: sortColumn() returns the most recently used sort column. The default value is -1, which means that this proxy model does not sort. Also, note that sort() sets the sortColumn() to the most recently used sort column.

Filtering
In addition to sorting, QSortFilterProxyModel can be used to hide items that do not match a certain filter. The filter is specified using a QRegularExpression object and is applied to the filterRole() (Qt::DisplayRole by default) of each item, for a given column. The QRegularExpression object can be used to match a regular expression, a wildcard pattern, or a fixed string. For example:

    proxyModel->setFilterRegularExpression(QRegularExpression("\.png", QRegularExpression::CaseInsensitiveOption));
    proxyModel->setFilterKeyColumn(1);

For hierarchical models, the filter is applied recursively to all children. If a parent item doesn't match the filter, none of its children will be shown.

A common use case is to let the user specify the filter regular expression, wildcard pattern, or fixed string in a QLineEdit and to connect the textChanged() signal to setFilterRegularExpression(), setFilterWildcard(), or setFilterFixedString() to reapply the filter.

Custom filtering behavior can be achieved by reimplementing the filterAcceptsRow() and filterAcceptsColumn() functions. For example (from the Custom Sort/Filter Model example), the following implementation ignores the filterKeyColumn property and performs filtering on columns 0, 1, and 2:

bool MySortFilterProxyModel::filterAcceptsRow(int sourceRow,
const QModelIndex &sourceParent) const
{
QModelIndex index0 = sourceModel()->index(sourceRow, 0, sourceParent);
QModelIndex index1 = sourceModel()->index(sourceRow, 1, sourceParent);
QModelIndex index2 = sourceModel()->index(sourceRow, 2, sourceParent);

return (sourceModel()->data(index0).toString().contains(filterRegularExpression())
        || sourceModel()->data(index1).toString().contains(filterRegularExpression()))
        && dateInRange(sourceModel()->data(index2).toDate());

}

(This code snippet comes from the Custom Sort/Filter Model example.)

If you are working with large amounts of filtering and have to invoke invalidateFilter() repeatedly, using beginResetModel() / endResetModel() may be more efficient, depending on the implementation of your model. However, beginResetModel() / endResetModel() returns the proxy model to its original state, losing selection information, and will cause the proxy model to be repopulated.

Subclassing
Since QAbstractProxyModel and its subclasses are derived from QAbstractItemModel, much of the same advice about subclassing normal models also applies to proxy models. In addition, it is worth noting that many of the default implementations of functions in this class are written so that they call the equivalent functions in the relevant source model. This simple proxying mechanism may need to be overridden for source models with more complex behavior; for example, if the source model provides a custom hasChildren() implementation, you should also provide one in the proxy model.

Note: Some general guidelines for subclassing models are available in the Model Subclassing Reference.

See also QAbstractProxyModel, QAbstractItemModel, Model/View Programming, Basic Sort/Filter Model Example, Custom Sort/Filter Model Example, and QIdentityProxyModel.

Property Documentation
[bindable, since 6.0]autoAcceptChildRows : bool
Note: This property supports QProperty bindings.

if true the proxy model will not filter out children of accepted rows, even if they themselves would be filtered out otherwise.

The default value is false.

This property was introduced in Qt 6.0.

See also recursiveFilteringEnabled and filterAcceptsRow().

[bindable]dynamicSortFilter : bool
Note: This property supports QProperty bindings.

This property holds whether the proxy model is dynamically sorted and filtered whenever the contents of the source model change

Note that you should not update the source model through the proxy model when dynamicSortFilter is true. For instance, if you set the proxy model on a QComboBox, then using functions that update the model, e.g., addItem(), will not work as expected. An alternative is to set dynamicSortFilter to false and call sort() after adding items to the QComboBox.

The default value is true.