QGraphicsRectItem with list of QStrings

[January]

Hi,
I want to make a class which will represent single entity in entity relationship diagram.
It should be an rect object with name and attributes which will adjust it's size to the text it is containing.
Because of that I am new to qt I started to play with qt doc and intuition which have led me to something like this:

class Entity : public QObject, public QGraphicsRectItem {
    Q_OBJECT;
 
public:
    Entity(QGraphicsItem *parent = 0);
 
    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
               QWidget *widget = 0);
    void setName(QString name);
    void addField(QString field);
 
private:
    void adjustRect();
 
    QString name;
    QList<QString> fields;
 
 
};
 
Entity::Entity(QGraphicsItem *parent)
    : QGraphicsRectItem(parent)
{
    setFlag(QGraphicsItem::ItemIsMovable);
    setFlag(QGraphicsItem::ItemIsSelectable);
}
 
void Entity::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    painter->setPen(Qt::black);
    painter->setBrush(QColor(230,230,230));
    painter->drawRect(rect());
 
    QPointF pos = QPointF(rect().x() + 10, rect().y() + 20);
    painter->drawText(pos, name);
 
    qDebug() << rect().width();
 
    painter->drawLine(pos.x() - 10, pos.y() + 5, pos.x() + rect().width() - 10, pos.y()+5);
 
    QString str;
    foreach(str, fields) {
        pos.setY(pos.y() + 20);
        painter->drawText(pos, str);
    }
 
}
 
void Entity::setName(QString name)
{
    this->name = name;
    adjustRect();
}
 
void Entity::addField(QString field)
{
    fields.append(field);
    adjustRect();
}
 
void Entity::adjustRect()
{
    qreal maxx = 20;
 
    maxx = (maxx < name.length()*10 ? name.length()*10 : maxx);
 
    QString str;
    foreach(str, fields) {
        maxx = (maxx < str.length()*10 ? str.length()*10 : maxx);
    }
 
    setRect(rect().x(), rect().y(), maxx, fields.count()*30 + 10);
}

class Entity : public QObject, public QGraphicsRectItem {
    Q_OBJECT;

public:
    Entity(QGraphicsItem *parent = 0);

    void paint(QPainter *painter, const QStyleOptionGraphicsItem *option,
               QWidget *widget = 0);
    void setName(QString name);
    void addField(QString field);

private:
    void adjustRect();

    QString name;
    QList<QString> fields;


};

Entity::Entity(QGraphicsItem *parent)
    : QGraphicsRectItem(parent)
{
    setFlag(QGraphicsItem::ItemIsMovable);
    setFlag(QGraphicsItem::ItemIsSelectable);
}

void Entity::paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget)
{
    painter->setPen(Qt::black);
    painter->setBrush(QColor(230,230,230));
    painter->drawRect(rect());

    QPointF pos = QPointF(rect().x() + 10, rect().y() + 20);
    painter->drawText(pos, name);

    qDebug() << rect().width();

    painter->drawLine(pos.x() - 10, pos.y() + 5, pos.x() + rect().width() - 10, pos.y()+5);

    QString str;
    foreach(str, fields) {
        pos.setY(pos.y() + 20);
        painter->drawText(pos, str);
    }

}

void Entity::setName(QString name)
{
    this->name = name;
    adjustRect();
}

void Entity::addField(QString field)
{
    fields.append(field);
    adjustRect();
}

void Entity::adjustRect()
{
    qreal maxx = 20;

    maxx = (maxx < name.length()*10 ? name.length()*10 : maxx);

    QString str;
    foreach(str, fields) {
        maxx = (maxx < str.length()*10 ? str.length()*10 : maxx);
    }

    setRect(rect().x(), rect().y(), maxx, fields.count()*30 + 10);
}

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It even works but it seems weird to me and I know there is better solution. Can you point me what am I doing wrong and where should I look for (classes, etc.).

I also don't know why entities are not selectable despite the fact I set the flag to ItemIsSelectable.