How to sort in TableView like QTableView?

[JohnDaYe]

i select a row like this

it will display after sort like this

how to let table view select the same data after a sort?

mymodel

//Header
#ifndef TABLEVIEWMODEL_H
#define TABLEVIEWMODEL_H

#include <QAbstractTableModel>

struct TableViewItem {
    int     iNumber;
    QString strName;
};

class TableViewModel
        : public QAbstractTableModel
{
    Q_OBJECT
    Q_PROPERTY(QString sortRole READ sortRole WRITE setSortRole)
public:
    enum {Role_Number = Qt::UserRole + 1, Role_Name};
    TableViewModel(QObject *parent);
    virtual ~TableViewModel() override;

    // QAbstractItemModel interface
public:
    int rowCount(const QModelIndex &parent) const override;
    int columnCount(const QModelIndex &parent) const override;
    QVariant data(const QModelIndex &index, int role) const override;
    QString sortRole() const;
    void setSortRole(QString sortRole);
    // QAbstractItemModel interface
public:
    QHash<int, QByteArray> roleNames() const override;
protected:
    int sortKey(const QString &name) const;
protected:
    QVector<TableViewItem> mData;
    QString mSortRole;
};

#endif // TABLEVIEWMODEL_H

//CPP
#include "tableviewmodel.h"
#include <algorithm>
#include <QDebug>
#include <QMap>
TableViewModel::TableViewModel(QObject *parent)
    : QAbstractTableModel(parent)
{
    mData.push_back({1, "Candy"});
    mData.push_back({2, "John"});
}

TableViewModel::~TableViewModel()
{

}


int TableViewModel::rowCount(const QModelIndex &parent) const
{
    Q_UNUSED(parent)
    return mData.size();
}

int TableViewModel::columnCount(const QModelIndex &parent) const
{
    Q_UNUSED(parent)
    return 2;
}

QVariant TableViewModel::data(const QModelIndex &index, int role) const
{
    if(!hasIndex(index.row(), index.column()))
        return QVariant();
    switch (role)
    {
        case Role_Number:
            return mData[index.row()].iNumber;
        case Role_Name:
            return mData[index.row()].strName;
    }
    return QVariant();
}

QHash<int, QByteArray> TableViewModel::roleNames() const
{
    QHash<int, QByteArray> roleName;
    roleName[Role_Number] = "number";
    roleName[Role_Name] = "name";
    return roleName;
}

QString TableViewModel::sortRole() const
{
    return mSortRole;
}

void TableViewModel::setSortRole(QString sortRole)
{
    mSortRole = sortRole;

    QVector<QPair<TableViewItem,int>> sortable;
    for (int row = 0; row < rowCount(QModelIndex()); ++row) {
        sortable.append({mData[row], row});
    }

    beginResetModel();
    int role = sortKey(mSortRole);
    switch (role)
    {
        case Role_Name:
        {
            std::stable_sort(mData.begin(), mData.end(), [](const TableViewItem &rhs, const TableViewItem &lhs){
               return lhs.strName < rhs.strName;
            });
        }
        break;
        case Role_Number:
        {
            std::stable_sort(mData.begin(), mData.end(), [](const TableViewItem rhs, const TableViewItem& lhs){
               return lhs.iNumber < rhs.iNumber;
            });
        }
        break;
    }
    endResetModel();
}

int TableViewModel::sortKey(const QString &name) const
{
    auto roleName = roleNames();
    for(auto it = roleName.begin(); it != roleName.end(); ++it)
    {
        if(it.value() == name)
            return it.key();
    }
    return -1;
}
//QML
import QtQuick 2.9
import QtQuick.Window 2.2
import QtQuick.Controls 1.4 as Ctrl14
import QtQuick.Controls 2.4
import QtQuick.Controls.Styles 1.4
Window {
    visible: true
    width: 640
    height: 480
    title: qsTr("Hello World")
    Ctrl14.TableView {
        x: 34
        y: 64
        width: 349
        height: 343
        id: tableView
        sortIndicatorVisible: true
        objectName: "tableView"
        selectionMode: Ctrl14.SelectionMode.ExtendedSelection
        Ctrl14.TableViewColumn {
            role: "number"
            title: "No."
        }
        Ctrl14.TableViewColumn {
            role: "name"
            title: "Name"
        }
        onSortIndicatorColumnChanged: {
            model.sortRole = tableView.getColumn(tableView.sortIndicatorColumn).role
        }
    }

    Button {
        id: button
        x: 397
        y: 378
        width: 74
        height: 29
        text: qsTr("Button")
    }
}

[SGaist]

Hi,

What version of Qt ?
On what OS ?
What type of model ?
How do you implement the sorting ?

[JohnDaYe]

Qt 5.11.2
Windows 10 64Bit
I already paste the code , thanks!

[SGaist]

What happens if rather than the begin/endResetModel, you just call dataChanged ?

[JohnDaYe]

@SGaist
I think, I don't need to call dataChanged

[JonB]

@JohnDaYe

I think, I don't need to call dataChanged

?

My advice would be: if @SGaist suggests you try something you heed it!

When you call beginResetModel Qt throws away all existing information about the model, including which row was selected. The view presumably then just remembers row #2 was selected and reselects that.

If instead you call dataChanged on each index it may remember which row in the model was selected and re-select the model row, not the view row number.

Otherwise, if that does not work or you wish to stick beginResetModel, before you sort you should store which row is selected by its content. That is usually the primary key, which looks like it might be your iNumber? Then after the sort you go find that row again by its content and reselect that. Any problem with that?

[JohnDaYe]

This post is deleted!

[JohnDaYe]

@JonB thanks
I try dataChanged, it does not work

and store selected and reselect is a good idea, but when I select large of data, it will be very slow,

QStandardItemModel is very fast, amazing

[JonB]

@JohnDaYe

and store selected and reselect is a good idea, but when I select large of data, it will be very slow,

Sorry, I don't understand? All you are supposed to store is the key of whichever row was previously selected, and then you re-find that in the new data order and select that item. What would be "slow"?

[JohnDaYe]

@JonB
and then you re-find that in the new data order and select that item.

this is qml code
tableview.selection.select(index)

if i select 10000 items, it is every slowly

[JonB]

@JohnDaYe
Let's be clear: I know nothing about QML.

tableview.selection.select(index)

This selects one row, the row numbered index, right? So how does that select 10,000 items?

[JohnDaYe]

do
tableview.selection.select(index)
10000 times

[JonB]

@JohnDaYe
Yes, but why in the world would you want to select a row 10,000 times, or reselect a given row 10,000 times?

I just don't get what you don't get?

1. Store the primary key of the currently selected row somewhere.
2. Call beginResetModel, do the sort, endResetModel.
3. Look through the rows in the newly-ordered model to find what the index is now of the row whose primary key you saved away. (Depending on what it's sorted by, this may be optimizable, or not.)
4. Call tableview.selection.select(index).

I haven't called select() 10,000 times, have I? I'm just selecting one row at the end.

[JohnDaYe]

@JonB

Thanks
I will read QStandardItemModel source code and learn some idea from it！

all the end！