How to display a simple QMap in a QTableView in Qt?

Question

I have a QMap called map. I initialize this map with couple of row of data from my database. Now I send this map to another class which contain GUI classes. In my GUI I have a TableView item. I need to show this map in any order in this TableView.

I have seen couple of examples, but all of them are for one vector which has only one field. And they used another class to form the view. I wondered if anyone has done this before and can help me with that.

Answer 1

Wrap the QMap in a subclass of QAbstractTableModel and set it to the view. Following, a basic functional example:

File "mapmodel.h"

#ifndef MAPMODEL_H
#define MAPMODEL_H

#include <QAbstractTableModel>
#include <QMap>

class MapModel : public QAbstractTableModel
{
    Q_OBJECT
public:

    enum MapRoles {
        KeyRole = Qt::UserRole + 1,
        ValueRole
    };

    explicit MapModel(QObject *parent = 0);
    int rowCount(const QModelIndex& parent = QModelIndex()) const;
    int columnCount(const QModelIndex& parent = QModelIndex()) const;
    QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const;
    inline void setMap(QMap<int, QString>* map) { _map = map; }

private:
    QMap<int, QString>* _map;
};

#endif // MAPMODEL_H

File "mapmodel.cpp"

#include "mapmodel.h"

MapModel::MapModel(QObject *parent) :
    QAbstractTableModel(parent)
{
    _map = NULL;
}

int MapModel::rowCount(const QModelIndex& parent) const
{
    if (_map)
        return _map->count();
    return 0;
}

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

QVariant MapModel::data(const QModelIndex& index, int role) const
{
    if (!_map)
        return QVariant();
    if (index.row() < 0 ||
        index.row() >= _map->count() ||
        role != Qt::DisplayRole) {
        return QVariant();
    }
    if (index.column() == 0)
        return _map->keys().at(index.row());
    if (index.column() == 1)
        return _map->values().at(index.row());
    return QVariant();
}

Example of use:

// ...
QMap<int, QString> map;
map.insert(1, "value 1");
map.insert(2, "value 2");
map.insert(3, "value 3");

MapModel mapmodel;
mapmodel.setMap(&map);

YourTableView.setModel(&mapmodel);
// ...

It will show a table view populated as follows: