QTableView doesn't update and has strange cell style by default

[deleted399]

Hi,

Why do the cells have these two squares on the right? This is a QTableView created with the Design tab.

Moreover, When I click de "Add product" button I call the update function on the model but the table doesn't display the value, what I'm missing?
The model of the table uses the m_activeProduct as underlying data.

Button logic

connect(ui->addProductButton, &QPushButton::clicked, this, [this](){
        Product p;
        p.m_name = "New product";
        p.m_price = 0.0;
        m_activeReceipt->addProduct(p);
        auto model = static_cast<ProductModel*>(ui->productsTableView->model());
        model->update();
    });

Model update

void ProductModel::update(){
    qDebug() << rowCount() << columnCount();
    auto top_left = index(0,0,QModelIndex());
    auto bottom_right = index(rowCount(),columnCount(),QModelIndex());
    emit dataChanged(top_left, bottom_right, {Qt::EditRole});
}

[Christian Ehrlicher]

Please show us your model. I don't see how changing m_activeReceipt should somehow magically update the model.

[deleted399]

Here is the .h

#ifndef PRODUCTMODEL_H
#define PRODUCTMODEL_H

#include <QAbstractTableModel>
#include "receipt.h"
class ProductModel : public QAbstractTableModel
{
public:
    ProductModel(Receipt * data, QObject* parent = nullptr);
    int rowCount(const QModelIndex &parent = QModelIndex()) const;
    int columnCount(const QModelIndex &parent = QModelIndex()) const;
    QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const;
    QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const;
    bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole);
    Qt::ItemFlags flags(const QModelIndex &index) const;
    void update( ) ;
private:
    Receipt * m_data;
};

#endif // PRODUCTMODEL_H

And the .cpp

#include "productmodel.h"
#include <QDebug>

ProductModel::ProductModel(Receipt *data, QObject *parent):
    QAbstractTableModel(parent),
    m_data(data)
{

}

int ProductModel::rowCount(const QModelIndex &parent) const
{
    return m_data->products().size();
}

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

QVariant ProductModel::headerData(int section, Qt::Orientation orientation, int role) const
{
    if (role != Qt::DisplayRole)
        return QVariant();

    if (orientation == Qt::Horizontal) {
        if (section % 2 == 0)
            return "Product";
        else
            return "Price";
    } else {
        return QString("%1").arg(section + 1);
    }
}

QVariant ProductModel::data(const QModelIndex &index, int role) const
{
    if (role == Qt::DisplayRole) {
        auto p = m_data->products();
        if(index.column() == 0)
            return p[index.row()].m_name;
        else if(index.column() == 1){
            return p[index.row()].m_price;
        }
    }
    else if (role == Qt::EditRole ) {
        auto p = m_data->products();
        if(index.column() == 0)
            return p[index.row()].m_name;
        else if(index.column() == 1){
            return p[index.row()].m_price;
        }
    }else{
        return QColor(Qt::white);
    }
    return QVariant();
}

bool ProductModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    bool ok;
    if (index.isValid() && role == Qt::EditRole) {
        if(index.column() == 0){
            auto p = m_data->products();
            p[index.row()].m_name = value.toString();
            emit dataChanged(index, index);
            return true;
        }
        else if( float val = value.toFloat(&ok); index.column() == 1 && ok){
            auto p = m_data->products();
            p[index.row()].m_price =val;
            emit dataChanged(index, index);
            return true;
        }
    }
    return false;
}

Qt::ItemFlags ProductModel::flags(const QModelIndex &index) const
{
    return QAbstractItemModel::flags(index) | Qt::ItemIsEditable;
}

void ProductModel::update(){
    auto top_left = index(rowCount()-1,columnCount()-1,QModelIndex());
    auto bottom_right = index(rowCount()-1,columnCount()-1,QModelIndex());
    emit dataChanged(top_left, bottom_right, {Qt::EditRole});
}

[Christian Ehrlicher]

So my question stands - how do you put your new data into the model?
Also you should not return QColor(Qt::white); for every role you don't process.

/edit: looks like you hold the data outside the model - don't do this.

[JonB]

@pachedo said in QTableView doesn't update and has strange cell style by default:

    auto bottom_right = index(rowCount(),columnCount(),QModelIndex());
    emit dataChanged(top_left, bottom_right, {Qt::EditRole});

In addition to @Christian-Ehrlicher .

This may not matter/be relevant to the behaviour you show, but I have two observations here:

• I think it ought be bottom_right = index(rowCount() - 1, columnCount() - 1, QModelIndex());

• If addProduct() adds a row to your model(?), dataChanged is not the right signal to emit. You should be using begin/endInsertRows().

Your

    }else{
        return QColor(Qt::white);
    }

probably means you are returning QColor(Qt::white); when this is called asking about whether the item has a checkbox, and maybe that is causing your checkbox(es) to be shown?