Change color of a row of a QSqlQueryModel (QTableView)?

Panoss

I 'm trying to change the color of rows in a QTableView which has a QSqlQueryModel as it's model, but it doesn't work.
This is the python compilable code:

import sys
from PyQt4 import QtGui, QtCore, QtSql
 
def main():
   app = QtGui.QApplication(sys.argv)
   w = MyWindow()
   w.show()
   sys.exit(app.exec_())
 
class MyWindow(QtGui.QTableView):
   def __init__(self, *args):
       QtGui.QTableView.__init__(self, *args)
 
       # connect to db (if doesn't exist, it's auto-created)
       self.db = QtSql.QSqlDatabase.addDatabase('QSQLITE')
       self.db.setDatabaseName('test.db')
       self.db.open()
 
       #create a table in db and add some data
       query = QtSql.QSqlQuery()
       query.exec_("DROP TABLE IF EXISTS games")
       query.exec_("CREATE TABLE games(id INTEGER PRIMARY KEY, hometeam TEXT, visitorteam TEXT) ")
       query.exec("INSERT INTO games (hometeam, visitorteam) VALUES ('Star', 'Eagles')")
       query.exec("INSERT INTO games (hometeam, visitorteam) VALUES ('Best team', 'Reds');")
 
       # set the model
       model = QtSql.QSqlQueryModel(self)
       self.setModel(model)
       model.setQuery("SELECT * FROM games")
 
       # paint first two rows
       for i in range(0, 2):
           model.setData(model.index(i, 0), QtGui.QBrush(QtCore.Qt.red), QtCore.Qt.BackgroundRole)
           model.setData(model.index(i, 1), QtGui.QBrush(QtCore.Qt.red), QtCore.Qt.BackgroundRole)
 
 
if __name__ == "__main__":
   main()

What might be the problem?

Panoss

Maybe I should subclass QSqlQueryModel?

Panoss

I subclassed it:

class ColorfullSqlQueryModel(QtSql.QSqlQueryModel):
    def __init__(self, dbcursor=None):
        super(ColorfullSqlQueryModel, self).__init__()

    def data(self, QModelIndex, role=None):
        v = QtSql.QSqlQueryModel.data(self, QModelIndex, role);
        if role == QtCore.Qt.BackgroundRole:
            return QtGui.QColor(QtCore.Qt.yellow)
        return (v);

It works!! Turns all rows to yellow!
But how can I make it paint ;only the rows I want?
How can I pass the color to function data?

c64zottel

@Panoss You are on the right track. That's exactly how the interface should be used. To your second question, your model has to decide, which of the background has to what color. To achieve this, you have to pass the information to the model. There is no unified way to do this. But here are two possibilities:

Either use setData, which comes with your model:

bool QAbstractItemModel::setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole)

http://doc.qt.io/qt-5/qabstractitemmodel.html#setData

Or you add and call some function designed by yourself. Anyway, if you change the underlying data after it is displayed, you have to signal the view that it has to update its content.

You may read up on that here (dataChanged or modelReset):
http://doc.qt.io/qt-5/qabstractitemmodel.html

Panoss

I changed function data to setData which has a parameter called 'p_object' and I use it for color:

    def setData(self, QModelIndex, p_object, role=None):
        v = QtSql.QSqlQueryModel.data(self, QModelIndex, role);
        if role == QtCore.Qt.BackgroundRole:
            self.dataChanged.emit(QModelIndex, QModelIndex)
            return QtGui.QColor(p_object)

        return (v);

I call it this way:

model.setData(index, QtCore.Qt.red, QtCore.Qt.BackgroundRole)

But it's not working, maybe the emit Signal is not correct.

c64zottel

@Panoss You really have to read up on the documentation. If you intend to work further with Qt's model system, there is no way around it. For this case, look here:
http://doc.qt.io/qt-5/qabstractitemmodel.html#setData

Panoss

c64zottel thank you, I saw in the link you posted that I have to emit the signal.
I tried with:

 self.dataChanged.emit(QModelIndex, QModelIndex)

But doesn't seem to work.
For sure, I 'm doing something wrong.

c64zottel

@Panoss Ok, this is Python anyway, I am out of my league here. But, as a last resort, you can try to call:
beginResetModel();
endResetModel();

Panoss

I tried with beginResetModel() and endResetModel() in many places witihn the function setData, but with no success.
I don't know what else should I try, any ideas are welcome.

c64zottel

@Panoss That was exactly how it works in my application. Maybe they just support the dataChanged signal, which you used earlier. But I just saw, that you do not specify the correct arguments. You have to send the signal like:

dataChanged( ModelIndex to first item changed, ModelIndex to last item changed )

Model indices can be created with:
QModelIndex QAbstractItemModel::index(int row, int column, const QModelIndex &parent = QModelIndex()) const

Panoss

@c64zottel said in Change color of a row of a QSqlQueryModel (QTableView)?:

@Panoss That was exactly how it works in my application.

Maybe you could post the code from your setData function?
And I will 'translate' it in python.

c64zottel

@Panoss I don't have a setData function. The code I use for reset is:

void BattlefieldModel::refresh( const QSet< LinearCoordinate > & indices ) {
    for( int lc : indices ) {
        QModelIndex a = index( lc );
        emit dataChanged( a, a );
    }
}

But this is only ok because, ... well lets not get into it.

The arguments of index ( row, column) is just the position you want to update. Since I have just rows, I update just rows.

VRonin

First of all, let me start by saying that using a QStandardItemModel filled manually from a QSqlQuery is probably the fastest way to go.

having said that you can use this proxy model to make it work:

Sorry for C++

#include <QIdentityProxyModel>
class  ExtraRolesProxyModel : public QIdentityProxyModel
{
    Q_OBJECT
    Q_DISABLE_COPY(ExtraRolesProxyModel)
public:
    explicit ExtraRolesProxyModel(QObject* parent=Q_NULLPTR)
        :QIdentityProxyModel(parent)
    {}
    virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const Q_DECL_OVERRIDE{
        const qint64 hashKey = (static_cast<qint64>(index.row()) << 32) | static_cast<qint64>(index.column());
        auto tableIter = m_extraRoles.constFind(hashKey);
        if(tableIter==m_extraRoles.constEnd())
            return QIdentityProxyModel::data(index,role);
        auto roleIter = tableIter.value().constFind(role);
        if(roleIter==tableIter.value().constEnd())
            return QIdentityProxyModel::data(index,role);
        return roleIter.value();
    }
    virtual bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) Q_DECL_OVERRIDE {
        if(!index.isValid())
            return false;
        Q_ASSERT(index.model()==this);
        const qint64 hashKey = (static_cast<qint64>(index.row()) << 32) | static_cast<qint64>(index.column());
        if(value.isValid()){
            m_extraRoles[hashKey][role] = value;
            emit dataChanged(index,index,QVector<int>(1,role));
            return true;
        }
        auto tableIter = m_extraRoles.find(hashKey);
        if(tableIter==m_extraRoles.end())
            return false;
        auto roleIter = tableIter.value().find(role);
        if(roleIter==tableIter.value().end())
            return false;
        tableIter.value().erase(roleIter);
        if(tableIter.value().isEmpty())
            m_extraRoles.erase(tableIter);
        emit dataChanged(index,index,QVector<int>(1,role));
        return true;
    }

private:
    QHash<qint64,QHash<qint32,QVariant> > m_extraRoles;
};

Panoss

How can this line be explained in plain english?

const qint64 hashKey = (static_cast<qint64>(index.row()) << 32) | static_cast<qint64>(index.column());

If index.row() is smaller than 32 thne hashkey = index.row().
Else hashkey = index.column()?

VRonin

@Panoss That row means: prepare an integer with 64 bits, the 32 leftmost bits will contain the row, the 32 rightmost the column. The bitshift operator is the same even in python https://wiki.python.org/moin/BitwiseOperators

Panoss

I translated it likes this: (I get no error on this line, seems ok)

hashKey = index.row() << 32 | index.column()

But this one;

 auto tableIter = m_extraRoles.constFind(hashKey);

Converted to python:

tableIter = m_extraRoles.constFind(hashKey)

Says variable m_extraRoles 'Unresolved reference'. It has not been declared anywhere.

VRonin

shouldn't it be this.m_extraRoles.constFind(hashKey) ?

Panoss

Yes, you 're right VRonin:

tableIter = self.m_extraRoles.constFind(hashKey)

This shows no underlined code in Pychrm (if there were any errors, it would be underlined. With red color.)

But this look very hard to convert to python:

Q_ASSERT(index.model()==this)

Q_ASSERT?? omg

VRonin

You can actually remove that line altogether, it's just a check that is done only in debug mode

Panoss

Only one (!!) line is left:

emit dataChanged(index,index,QVector<int>(1,role));

Translated to:

self.dataChanged.emit(index,index,QVector(int((1,role)))

But there is no QVector in Python.
(I mean it doesn't exist in any library like PyQt4.QtCore)