问题
I am having a problem to properly transpose the table I recieve from db. I followed the path found here , and ended up in subclassing a QAbstractProxyModel - like described here . unfortunatelly, it doesn't fully work, here's where the problem is:
What I have:
X | A | B
----------
1 | A1 | B1
2 | A2 | B2
What I want:
X | 1 | 2
----------
A | A1 | A2
B | B1 | B2
What I get:
X | 1 | 1
----------
A | A1 | A2
A | B1 | B2
So as you can see, the data is correctly transposed, but the headers get bad... And I really need them :(
I tried to manually set header data, but it also failed:
origModel = new QSqlQueryModel; // set query and so on
transposedModel = new TransposeProxyModel;
transposedModel->setSourceModel(origModel );
for (int i = 0; i < origModel->columnCount(); i++) {
qDebug() << "origModel->Qt::Horizontal(" << i << ")" << origModel->headerData(i, Qt::Horizontal, Qt::DisplayRole);
//transposedModel->setHeaderData(i, Qt::Vertical, origModel->headerData(i, Qt::Horizontal, Qt::DisplayRole), Qt::DisplayRole); //#try1
transposedModel->setHeaderData(i, Qt::Vertical, QVariant( "abc" ), Qt::DisplayRole); // #try2
}
No matter if I try #1, or #2 - call to setHeaderData evaluates to false...
Any ideas?
fixed as @Vinícius Gobbo A. de Oliveira pointed
回答1:
Well, if you used the example code you linked you should override the default definition for the headerData method of the TransposeProxyModel class, just like this:
QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const {
return sourceModel()->headerData(section, (orientation == Qt::Horizontal ? Qt::Vertical : Qt::Horizontal), role);
}
Forget about the setHeaderData and setData methods: you want a proxy model that rely on the original one!
Well, don't know exactly what's wrong, which Qt release are you using? Try this code, it works perfectly here:
#include <QtCore>
#include <QtWidgets>
class TransposeProxyModel: public QAbstractProxyModel {
public:
TransposeProxyModel(QObject *p = 0):
QAbstractProxyModel(p)
{
}
QModelIndex mapFromSource ( const QModelIndex & sourceIndex ) const{
return index(sourceIndex.column(), sourceIndex.row());
}
QModelIndex mapToSource ( const QModelIndex & proxyIndex ) const{
return sourceModel()->index(proxyIndex.column(), proxyIndex.row());
}
QModelIndex index(int r, int c, const QModelIndex &ind=QModelIndex()) const{
return createIndex(r,c);
}
QModelIndex parent(const QModelIndex&) const {
return QModelIndex();
}
int rowCount(const QModelIndex &) const{
return sourceModel()->columnCount();
}
int columnCount(const QModelIndex &) const{
return sourceModel()->rowCount();
}
QVariant data(const QModelIndex &ind, int role) const {
return sourceModel()->data(mapToSource(ind), role);
}
QVariant headerData(int section, Qt::Orientation orientation,
int role = Qt::DisplayRole) const {
return sourceModel()->headerData(section,
(orientation == Qt::Horizontal ? Qt::Vertical : Qt::Horizontal),
role);
}
};
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QStandardItemModel model(3,3);
model.setData(model.index(0,0), "1");
model.setData(model.index(0,1), "2");
model.setData(model.index(0,2), "3");
model.setData(model.index(1,0), "4");
model.setData(model.index(1,1), "5");
model.setData(model.index(1,2), "6");
model.setData(model.index(2,0), "7");
model.setData(model.index(2,1), "8");
model.setData(model.index(2,2), "9");
model.setHeaderData(0, Qt::Horizontal, "a");
model.setHeaderData(1, Qt::Horizontal, "b");
model.setHeaderData(2, Qt::Horizontal, "c");
TransposeProxyModel trans;
trans.setSourceModel(&model);
QSplitter split;
QTableView *t1 = new QTableView(&split);
t1->setModel(&model);
QTableView *t2 = new QTableView(&split);
t2->setModel(&trans);
split.show();
return a.exec();
}
Most of the code came from the link you provided, I just wrote the headerData method.
回答2:
Funny thing though - the doc states that this is a virtual method:
virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const
(...)
QVariant QAbstractProxyModel::headerData(int section, Qt::Orientation orientation, int role) const [virtual]
Reimplemented from QAbstractItemModel::headerData().
but in the actual headerthe virtual keyword is missing:
C:\Qt\Qt5.2.1\5.2.1\msvc2010\include\QtCore\qabstractproxymodel.h
(...)
QVariant data(const QModelIndex &proxyIndex, int role = Qt::DisplayRole) const; //line76
QVariant headerData(int section, Qt::Orientation orientation, int role) const; //line77
I checked in normal Qt dir and it is also missing:
C:\Qt\Qt5.2.1\5.2.1\Src\qtbase\src\corelib\itemmodels\qabstractproxymodel.h
(...)
QVariant data(const QModelIndex &proxyIndex, int role = Qt::DisplayRole) const;
QVariant headerData(int section, Qt::Orientation orientation, int role) const;
I have made a test:
sim = new QStandardItemModel (3,3);
for (int i = 0; i < 3; i++) {
for (int j = 0; j < 3; j++ ) {
sim->setData(sim->index(i,j), QString("%1%2").arg(QChar(j+65), QString().setNum(i+1)));
if (i==0)
sim->setHeaderData(j, Qt::Horizontal, QChar(j+65));
}
sim->setHeaderData(i, Qt::Vertical, i+1);
}
transposedModel = new TransposeProxyModel;
transposedModel->setSourceModel(sim);
QAbstractItemModel * aim = transposedModel;
QAbstractProxyModel *apm = transposedModel;
for (int i = 0; i < apm->rowCount(); i++) {
qDebug() << "aim->Qt::Vertical(" << i << ")" << aim->headerData(i, Qt::Vertical, Qt::DisplayRole);
qDebug() << "apm->Qt::Vertical(" << i << ")" << apm->headerData(i, Qt::Vertical, Qt::DisplayRole);
qDebug() << "transposedModel->Qt::Vertical(" << i << ")" << transposedModel->headerData(i, Qt::Vertical, Qt::DisplayRole);
}
And the debug is:
aim->Qt::Vertical( 0 ) QVariant(int, 1)
apm->Qt::Vertical( 0 ) QVariant(int, 1)
[ TransposeProxyModel::headerData ] //qDebug in TransposeProxyModel::headerData
transposedModel->Qt::Vertical( 0 ) QVariant(QChar, 'A')
aim->Qt::Vertical( 1 ) QVariant(int, 1)
apm->Qt::Vertical( 1 ) QVariant(int, 1)
[ TransposeProxyModel::headerData ] //qDebug in TransposeProxyModel::headerData
transposedModel->Qt::Vertical( 1 ) QVariant(QChar, 'B')
aim->Qt::Vertical( 2 ) QVariant(int, 1)
apm->Qt::Vertical( 2 ) QVariant(int, 1)
[ TransposeProxyModel::headerData ] //qDebug in TransposeProxyModel::headerData
transposedModel->Qt::Vertical( 2 ) QVariant(QChar, 'C')
So I guess that's the problem - the method isn't abstract, and that's why it doesn't call my overridden method. Qt bug ? or is that on purpose? I also took a peek into
C:\Qt\Qt5.2.1\5.2.1\Src\qtbase\src\corelib\itemmodels\qabstractproxymodel.cpp
/*!
\reimp
*/
QVariant QAbstractProxyModel::headerData(int section, Qt::Orientation orientation, int role) const
{
Q_D(const QAbstractProxyModel);
int sourceSection;
if (orientation == Qt::Horizontal) {
const QModelIndex proxyIndex = index(0, section);
sourceSection = mapToSource(proxyIndex).column();
} else {
const QModelIndex proxyIndex = index(section, 0);
sourceSection = mapToSource(proxyIndex).row();
}
return d->model->headerData(sourceSection, orientation, role);
}
I guess it should get proper header anyway - it calls mapToSource, which is pure virtual, and this should obtain the correct index?
来源：https://stackoverflow.com/questions/26050030/swapping-headers-in-qsqlquerymodel-transpose-table