QSqlRelationalTableModel QTableView colorizing rows

Question

What is the right way to color-code rows in a QTableView?

I'm developing a spreadsheet application that should color-code its rows based on a specific value set in one of the columns. I use QSqlRelationalTableModel and QSqlRelationalDelegate; because, the value that should determine the color is a foreign key.

Why can't it be as simple as the following? Any ideas?

model->setData( model->index( index.row(), index.column() ), 
                QBrush(Qt::red),
                Qt::BackgroundRole );

Answer 1

You should overwrite the data function of QSqlRelationalTableModel and when you get the Qt :: BackgroundRole role to filter according to your case and return the appropriate QBrush, in the following example filter by the foreign field and check that it is equal to Lima:

Example:

sqlrelationaltablemodel.h

#ifndef SQLRELATIONALTABLEMODEL_H
#define SQLRELATIONALTABLEMODEL_H

#include <QSqlRelationalTableModel>

class SqlRelationalTableModel : public QSqlRelationalTableModel
{
    Q_OBJECT
public:
    SqlRelationalTableModel(QObject * parent = 0, QSqlDatabase db = QSqlDatabase());

     QVariant data(const QModelIndex & item, int role = Qt::DisplayRole) const;
};

#endif // SQLRELATIONALTABLEMODEL_H

sqlrelationaltablemodel.cpp

#include "sqlrelationaltablemodel.h"

#include <QBrush>

SqlRelationalTableModel::SqlRelationalTableModel(QObject *parent, QSqlDatabase db)
    :QSqlRelationalTableModel(parent, db)
{

}

QVariant SqlRelationalTableModel::data(const QModelIndex &item, int role) const
{
    if(role == Qt::BackgroundRole)
        if(QSqlRelationalTableModel::data(index(item.row(), 2), Qt::DisplayRole).toString().trimmed() == "Lima")
                        return QVariant(QBrush(Qt::red));
    return QSqlRelationalTableModel::data(item, role);
}

Output:

The complete example can be found here.