Listmodel seft destroy on scrolling then crash app

RyuShai

Hi, im try make move item from listViewA to listViewB. But when i'm copied, sometime listmodel self-destroyed and make my app crash.
Code is complicated so i cant push code right now, see error on video i recorded here video

i create custom model like this

class Q_PersonInfoModel : public QAbstractListModel
{
    Q_OBJECT
    Q_PROPERTY(ListPersonInfo *lpi READ lpi WRITE setlpi)
public:
    Q_PersonInfoModel(QObject *parent = nullptr);
    ~Q_PersonInfoModel();
    // QAbstractItemModel interface
public:
    enum {
        ID = 0,
        NAME,
        S3_FRAME_URL,
        S3_IMAGE_URL,
        CREATE_DATE,
        UPDATE_DATE
    };
    virtual int rowCount(const QModelIndex &parent) const override;
    virtual QVariant data(const QModelIndex &index, int role) const override;
    virtual bool setData(const QModelIndex &index, const QVariant &value, int role) override;
    virtual QHash<int, QByteArray> roleNames() const override;
    ListPersonInfo *lpi()const;
    void setlpi (ListPersonInfo *mlpi);
private:
    ListPersonInfo *mLpi;

data save on class ListPersonInfo like this

class ListPersonInfo : public QObject
{
    Q_OBJECT
public:
    explicit ListPersonInfo(QObject *parent = nullptr);
//    static ListPersonInfo *getInstance();
    void addItem(PersonInfo item);
    void removeItem(int pos);
    QList<PersonInfo> getData() ;
    ~ListPersonInfo();
    void setData(const QList<PersonInfo> &data);

signals:
    void preItemAppended();
    void postItemAppended();

    void preItemRemoved(int index);
    void postItemRemoved();

    void preResetItem();
    void posResetItem();

    void modelChanged(QString stct);

public slots:
private:
    QList<PersonInfo> mData;
    int count=0;
//    static ListPersonInfo *instance;
};

assign model to customModel by call Q_INVOKABLE method return ListPersonInfo

ListPersonView.qml
....
 listPersonModel.lpi: controler.getListPersonInfo(index)

here the method getListPersonInfo(positionInList)

ListPersonInfo *MainControler::getListPersonInfo(int pos){
    DB("pos: "<<pos);

    return groupCluster[pos];
}

declare groupCluster here

QList<ListPersonInfo *> groupCluster;

any idea why it destroy and how should i do for right ?

UPDATE:
root cause may is parent of model your for listview custom model (ListPersonInfo in this case)
i use QQmlEngine::setObjectOwnership(); then no more crash hehe

J.Hilk

hi @RyuShai

I don't see the implementation so I have to ask, your ListPersonInfoobjectes do you give them your c++ class as parent?

If they are without c++ parent the QML-Enging should take ownership of them and the GC may or may not delete them at random

RyuShai

@J.Hilk said in Listmodel seft destroy on scrolling then crash app:

s do you give them your c++ cla

i dont set ListPersonInfo parent, i set it default = 0
ListPersonInfo.h

explicit ListPersonInfo(QObject *parent = 0);

ListPersonInfo.cpp

ListPersonInfo::ListPersonInfo(QObject *parent) : QObject(parent)
{

}

so parent = 0 is problem do you think ?

J.Hilk

@RyuShai it's a possibility

RyuShai

@J.Hilk
i think you right, just found solution on stackoverflow with QQmlEngine::setObjectOwnership();

however, still dont understand your idea, which parent should i give ListPersonInfo when create new one

J.Hilk

@RyuShai said in Listmodel seft destroy on scrolling then crash app:

@J.Hilk
however, still dont understand your idea, which parent should i give ListPersonInfo when create new one

probably controler (no idea what the actual c++ class is named)

99% chance, you can simply give this as parent during creation of the ListPersonInfo object