QAbstractItemModel beginInsertRow, reenumerate other rows?

[Marek]

Hi
I have question:
I'm adding data to QAbstractItemModel that was previously set. I have

struct DevPlaceDataStruct {
    int         row;
    int         dev_id;
    QString     text;
};

and of course

private:
    QMap<int,DevPlaceDataStruct*> modelMap;

Model is indexed in modelMap by (int)row. So if I add a new row, I need to reenumerate the rest of rows, right?
beginInsertRows only notifies the model about the change?
So in consequence I need to change modelMap from the row position I'm inserting to the end ?

best,
Marek

[Christian Ehrlicher]

Why not simply use a QVector<DevPlaceDataStruct*> instead? Then use the index as row and all works without additional stuff.

[Marek]

@Christian-Ehrlicher actually... I haven't thought about this earlier, because every subclass of QAbstractListModel I have seen used QMap not QVector but yes it should work.
Thanks,
Marek

[AndyS]

@Marek can you marked this as solved if @Christian-Ehrlicher's answer solves the issue for you? Thanks.

[Marek]

@AndyS Yes I will, it looks like it is sound sollution, I just couldn't find time to test it ;) I will try it ASAP.

[Marek]

Hi
Actually I have problem with both methods QVector and QMap it gives me the same result.
Problem is when I remove row=0 and then I add item which should go into row=0.
Result is that I have in view: Item1, Item2, black space, item3.
When I add row in the middle or at the end it is OK.
When I'm checking debug it looks like it should work, row is correct, model count is correct

DevPlaceModel::removeRow dev_id: 74  row: 0  count: 2
DevPlaceModel::addRow dev_id: 74  place_number: 1  row: 0  count: 3

I have attached cpp, h and qml file.
Cpp and h has commented out version with QMap, so it works with QVector, but both methods have a problem with row=0.
At the beginning I'm settings model from another class by calling
beginSetModel();
addPlace(int dev_id,int place_number);
endSetModel();

When model is set I'm using
addRow(int dev_id,int place_number);
removeRow(int dev_id);

Can someone shed some light?

Best,
Marek

#include <QtCore>
#include <QAbstractListModel>
#include <QtXml/QDomNode>
#include <QtXml/QDomElement>
#include <QGeoCoordinate>
#include <QGeoRectangle>
#include "helper.h"


struct DevPlaceDataStruct {
    int         row;
    int         dev_id;
    int         place_number;
    QString     text;
};

class DevPlaceModel : public QAbstractListModel
{
    Q_OBJECT
public:
    enum ItemRoles {
        IdRole = Qt::UserRole + 1,
        TextRole = Qt::UserRole + 2,
        RowRole = Qt::UserRole + 3,
    };

    DevPlaceModel(QObject *parent);

    virtual int rowCount(const QModelIndex&) const { return vector.count(); }
  //  virtual int rowCount(const QModelIndex&) const { return modelMap.count(); }
    virtual QVariant data(const QModelIndex &index, int role) const;

    QHash<int, QByteArray> roleNames() const;
    Q_INVOKABLE int getRow(int dev_id);
    Q_INVOKABLE int getDevId(int row);
public slots:
    void beginSetModel();
    void addPlace(int dev_id,int place_number);
    void addRow(int dev_id,int place_number);
    void removeRow(int dev_id);
    void endSetModel();
signals:

private slots:
    QVariant getRoleData(int role,int row) const;
private:
    QVector<DevPlaceDataStruct*> vector;
  //  QMap<int,DevPlaceDataStruct*> modelMap;
    QHash<int, QByteArray> roles;
    int     curr_dev_id;
};

#include "dev-place-model.h"

DevPlaceModel::DevPlaceModel(QObject *parent):QAbstractListModel(parent) {

    roles[IdRole] = "id_role";
    roles[TextRole]= "text_role";
    roles[RowRole]= "row_role";

    curr_dev_id=0;
}
QHash<int, QByteArray> DevPlaceModel::roleNames() const {
    return roles;
}
QVariant DevPlaceModel::data(const QModelIndex &index, int role) const {
    if(!index.isValid()) {
        return QVariant();
    }
    if(roles.contains(role) && vector.count()-1>=index.row()) {
        return getRoleData(role,index.row());
    }
//    if(roles.contains(role) && modelMap.contains(index.row())) {
//        return getRoleData(role,index.row());
//    }
    return QVariant();
}
QVariant DevPlaceModel::getRoleData(int role, int row) const {
    DevPlaceDataStruct *p=vector.at(row);
//    DevPlaceDataStruct *p=modelMap[row];
    switch(role) {
    case IdRole:
        return QVariant(p->dev_id);
    case TextRole:
        return QVariant(p->text);
    case RowRole:
//        return QVariant(p->row);
        return QVariant(row);
    default:
        qWarning()<<"DevPlaceModel::getRoleData there is no role:"<<role;
    }
}
void DevPlaceModel::beginSetModel() {
    beginResetModel();
    for(int i=0;i<vector.count();i++) {
        delete vector.at(i);
    }
    vector.clear();

//    beginResetModel();
//    if(modelMap.count()) {
//        QMapIterator<int,DevPlaceDataStruct*> i(modelMap);
//        while(i.hasNext()) {
//            i.next();
//            delete i.value();
//        }
//        modelMap.clear();
//    }
}
void DevPlaceModel::addPlace(int dev_id, int place_number) {
    qDebug()<<"DevPlaceModel::addPlace dev_id:"<<dev_id<<" place_number:"<<place_number;
    DevPlaceDataStruct *p=new DevPlaceDataStruct;
    p->dev_id=dev_id;
    p->text=QString("Miejsce: %1").arg(place_number);
    p->place_number=place_number;
    vector.append(p);
//    p->row=modelMap.count();
//    modelMap.insert(p->row,p);
}
void DevPlaceModel::endSetModel() {
    emit endResetModel();
}
void DevPlaceModel::addRow(int dev_id, int place_number) {
    int row=-1;
    for(int i=0;i<vector.count();i++) {
        DevPlaceDataStruct *d=vector.at(i);
        if(d->place_number>=place_number) {
            row=((i-1)<0 ? 0 : i-1);
            break;
        }
    }
    if(row==-1) {
        row=vector.count();
    }
    DevPlaceDataStruct *em=new DevPlaceDataStruct;
    em->dev_id=dev_id;
    em->text=QString("Miejsce: %1").arg(place_number);
    em->place_number=place_number;
    emit beginInsertRows(QModelIndex(),row,row);
    vector.insert(row,em);
    emit endInsertRows();
    qDebug()<<"DevPlaceModel::addRow dev_id:"<<dev_id<<" place_number:"<<place_number<<" row:"<<row<<" count:"<<vector.count();

//    int row=-1;
//    bool found=false;
//    int new_idx=0;
//    QMap<int,DevPlaceDataStruct*> new_modelMap;
//    QMapIterator<int,DevPlaceDataStruct*> i(modelMap);
//    while(i.hasNext()) {
//        i.next();
//        if(!found && i.value()->place_number>=place_number) {
//            row=((i.value()->row-1)<0 ? 0 : i.value()->row-1);
//            found=true;
//            new_idx++;
//        }
//        i.value()->row==new_idx;
//        new_modelMap.insert(new_idx,i.value());
//        new_idx++;

//    }
//    if(row==-1) {
//        row=modelMap.count();
//    }
//    DevPlaceDataStruct *em=new DevPlaceDataStruct;
//    em->dev_id=dev_id;
//    em->text=QString("Miejsce: %1").arg(place_number);
//    em->place_number=place_number;
//    em->row=row;
//    emit beginInsertRows(QModelIndex(),row,row);
//    new_modelMap.insert(em->row,em);
//    modelMap.clear();
//    modelMap=new_modelMap;
//    emit endInsertRows();
//    qDebug()<<"DevPlaceModel::addRow dev_id:"<<dev_id<<" place_number:"<<place_number<<" row:"<<row<<" count:"<<modelMap.count();

}
void DevPlaceModel::removeRow(int dev_id) {
    int row=-1;
    for(int i=0;i<vector.count();i++) {
        DevPlaceDataStruct *d=vector.at(i);
        if(d->dev_id==dev_id) {
            row=i;
            break;
        }
    }
    if(row>=0) {
        beginRemoveRows(QModelIndex(),row,row);
        delete vector.at(row);
        vector.remove(row);
        endRemoveRows();
    }
    qDebug()<<"DevPlaceModel::removeRow dev_id:"<<dev_id<<" row:"<<row<<" count:"<<vector.count();

//    int row=-1;
//    int new_idx=0;
//    QMap<int,DevPlaceDataStruct*> new_modelMap;
//    QMapIterator<int,DevPlaceDataStruct*> i(modelMap);
//    while(i.hasNext()) {
//        i.next();
//        if(i.value()->dev_id==dev_id) {
//            row=i.key();
//        }
//        else {
//            i.value()->row=new_idx;
//            new_modelMap.insert(new_idx,i.value());
//            new_idx++;
//        }
//    }
//    if(row<0) {
//        qWarning()<<"DevPlaceModel::removeRow no row:"<<row;
//        return;
//    }
//    beginRemoveRows(QModelIndex(),row,row);
//    delete modelMap[row];
//    modelMap.clear();
//    modelMap=new_modelMap;
//    endRemoveRows();
//    qDebug()<<"DevPlaceModel::removeRow dev_id:"<<dev_id<<" row:"<<row<<" count:"<<modelMap.count();
}
int DevPlaceModel::getRow(int dev_id) {
    for(int i=0;i<vector.count();i++) {
        DevPlaceDataStruct *d=vector.at(i);
        if(d->dev_id==dev_id)
            return i;
    }
    return -1;

//    QMapIterator<int,DevPlaceDataStruct*> i(modelMap);
//    while(i.hasNext()) {
//        i.next();
//        if(i.value()->dev_id==dev_id)
//            return i.value()->row;
//    }
//    return 0;
}
int DevPlaceModel::getDevId(int row) {
    if(vector.count()-1>=row) {
        qWarning()<<"DevPlaceModel::getDevId there is no row:"<<row;
        return 0;
    }
    return vector.at(row)->dev_id;

//    if(!modelMap.contains(row)) {
//        qWarning()<<"DevPlaceModel::getDevId there is no row:"<<row;
//        return 0;
//    }
//    return modelMap[row]->dev_id;
}

QControls2.ComboBox {
            id:placeCombo
            anchors.top:addressText.bottom
            anchors.horizontalCenter: parent.horizontalCenter
            width:parent.width*0.6
            height:parent.height*0.15
            model: DevPlaceModel
            textRole:"text_role"
           // currentIndex:DevPlaceModel.getRow(root.dev_id)
        }

[JonB]

@Marek
Two observations:

1. It does not actually matter, but why does your beginSetModel() call beginResetModel(); directly while endSetModel() does an emit endResetModel();?

2. Your addRow()'s row=((i-1)<0 ? 0 : i-1); returns 0 for all 3 row == -1 and row == 0 and row == 1. Is that related to your problem?

[Marek]

@JonB

1. My mistake shold call endResetModel
2. This is correct I think, It is in loop from i=0 to vector.count. So when I have items (2,3) in vector and I'm adding item 1, it will go to row=0
   When I have items 1,3 and I'm adding item 2 it will go to row=1
   Right?

[JonB]

@Marek
I don't know, I don't claim to follow your code. I'm just "surprised" that an insert where row == 0 and row == 1 both map to row 0.

[Marek]

@JonB IMHO model is OK, when I remove and then add item 1 (I have 1,2,3) from debug I have:

DevPlaceModel::removeRow dev_id: 74  row: 0  count: 2
DevPlaceModel::addRow dev_id: 74  place_number: 1  row: 0  count: 3  vector: QVector(0x5636891742c0, 0x56368c2e0a90, 0x56368c23d700)

So view should have 3 items, instead there is like in image (

[Marek]

Hi
Sorry for late reply. I don't have this problem in view like ListView, maybe it is some bug in QControls Combo, I need to prepare sample and report.
Definitelly using QVector instead of QMap is more convinient in model,
thanks for the hint.
Best,
Marek