How to update QTableView when rows are inserted to it
-
I am trying to insert rows to
QTableViewset toQAbstractTableModelusing drag of item from another TreeView on to the QTableView.//Constructor of Tableview model= new TableModel(); TableRowCount=0; model->rCount=TableRowCount; this->setModel(model); setAcceptDrops(true); //dropEvent QTreeView * view= dynamic_cast<QTreeView*>(event->source()); QModelIndexList list= view->selectionModel()->selectedIndexes(); for(int i=0;i<list.count();i++) { QModelIndex dragIndex=list.at(i); if(dragIndex.parent().isValid()) { TableRowCount++; model->rCount=TableRowCount; TableStruct Tstruct; Tstruct.DeviceName=dragIndex.parent().data(Qt::DisplayRole).toString(); Tstruct.MessageName=dragIndex.parent().data(Qt::DisplayRole).toString(); Tstruct.TagName=dragIndex.data(Qt::DisplayRole).toString(); Tstruct.Value=QString::number(0); Tstruct.Units=QString::number(0); TableStrList.append(Tstruct); model->TableList=TableStrList; model->insertRows(TableRowCount,1,dragIndex);And model looks like
QVariant Model::data(const QModelIndex &index, int role) const { if (role == Qt::DisplayRole) { int column = index.column(); int row = index.row(); switch(column) { case 0: return TableList.at(row).DeviceName; break; case 1: return TableList.at(row).MessageName; break; case 2: return TableList.at(row).TagName; break; case 3: return TableList.at(row).Value; break; case 4: return TableList.at(row).Units; break; } } if(role == Qt::TextAlignmentRole) { return Qt::AlignCenter; } return QVariant(); } int Model::rowCount(const QModelIndex & /*parent*/) const { qDebug()<< "row count "<<rCount; return rCount; } int Model::columnCount(const QModelIndex & /*parent*/) const { return 5; } QVariant Model::headerData( int section,Qt::Orientation orientation,int role ) const { if((role == Qt::DisplayRole || role ==Qt::ToolTipRole)) { if(orientation == Qt::Horizontal) { switch( section ) { case 0: return( QString( "Device Name" ) ); case 1: return( QString( "Message Name" ) ); case 2: return( QString( "Tag Name" ) ); case 3: return( QString( "Value" ) ); case 4:return (QString("units")); } } } return QAbstractItemModel::headerData( section, orientation, role ); } bool Model::insertRows(int row, int count, const QModelIndex &parent) { beginInsertRows(parent,row,row+count-1); endInsertRows(); return true; }Row count in the model is updated properly on drop of item but the view is not getting updated. How will the will know that the new rows re inserted??
@Ratzz
Hello,
I believe you should emit the QAbstractItemModel::rowsInserted signal from the model (after your call toendInsertRows), so the view knows to adapt to the changes.Kind regards.
PS:
switch(column) { case 0:You should really use (possibly unnamed) enums for that kind of switch constructs.
Read and abide by the Qt Code of Conduct
-
@Ratzz
Hello,
I believe you should emit the QAbstractItemModel::rowsInserted signal from the model (after your call toendInsertRows), so the view knows to adapt to the changes.Kind regards.
PS:
switch(column) { case 0:You should really use (possibly unnamed) enums for that kind of switch constructs.
-
@kshegunov
Thanks for the reply.
But doc saysNote: This is a private signal. It can be used in signal connections but cannot be emitted by the user.What does this mean?
@Ratzz
It means it can't be emitted from the user of the class. Since you're not the user of the class, but rather the designer, I think you should just ignore the note. ;)Read and abide by the Qt Code of Conduct
-
@Ratzz
It means it can't be emitted from the user of the class. Since you're not the user of the class, but rather the designer, I think you should just ignore the note. ;)@kshegunov
It asks for QPrivateSignal http://postimg.org/image/bjpuc4bep/--Alles ist gut.
-
@kshegunov
It asks for QPrivateSignal http://postimg.org/image/bjpuc4bep/@Ratzz
Oops, sorry. The note above the one you cited states:It can only be emitted by the QAbstractItemModel implementation, and cannot be explicitly emitted in subclass code.Hm, in that case I'm not sure ... The documentation is somewhat cryptic whether
endInsertRows()actually emits the aforementioned signal ...Read and abide by the Qt Code of Conduct
-
@kshegunov
It asks for QPrivateSignal http://postimg.org/image/bjpuc4bep/@Ratzz
Possibly, you could try implementing QAbstractItemModel::dropMimeData without intercepting the drop event? -
@Ratzz
Oops, sorry. The note above the one you cited states:It can only be emitted by the QAbstractItemModel implementation, and cannot be explicitly emitted in subclass code.Hm, in that case I'm not sure ... The documentation is somewhat cryptic whether
endInsertRows()actually emits the aforementioned signal ...@kshegunov
ThebeginInsertRowsdoc http://doc.qt.io/qt-4.8/qabstractitemmodel.html#beginInsertRows saysNote: This function emits the rowsAboutToBeInserted() signal which connected views (or proxies) must handle before the data is inserted. Otherwise, the views may end up in an invalid state.Will it help?
--Alles ist gut.
-
@kshegunov
ThebeginInsertRowsdoc http://doc.qt.io/qt-4.8/qabstractitemmodel.html#beginInsertRows saysNote: This function emits the rowsAboutToBeInserted() signal which connected views (or proxies) must handle before the data is inserted. Otherwise, the views may end up in an invalid state.Will it help?
@Ratzz
Yes, I saw that, but this is to notify the view insertions will be happening. The question is whetherendInsertRows()emitsrowsInserted()thus telling the view the insertion has finished and it can actually update itself. Unfortunately, the documentation doesn't state anything specific aboutendInsertRows(), unless I completely missed it ...PS. I just noticed something in your code:
QTreeView * view= dynamic_cast<QTreeView*>(event->source());Is this a typo?
Read and abide by the Qt Code of Conduct
-
Hi,
The documentation doesn't specify but the implementation does emit rowsInserted. However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.
Interested in AI ? www.idiap.ch
Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct -
@Ratzz
Yes, I saw that, but this is to notify the view insertions will be happening. The question is whetherendInsertRows()emitsrowsInserted()thus telling the view the insertion has finished and it can actually update itself. Unfortunately, the documentation doesn't state anything specific aboutendInsertRows(), unless I completely missed it ...PS. I just noticed something in your code:
QTreeView * view= dynamic_cast<QTreeView*>(event->source());Is this a typo?
@kshegunov said:
Is this a typo?
I drag the items from another QTreeView .The cast is for that..
Did you mean that? -
Hi,
The documentation doesn't specify but the implementation does emit rowsInserted. However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.
-
Hi,
The documentation doesn't specify but the implementation does emit rowsInserted. However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.
However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.
After a quick look (without pretense to be complete) I couldn't clearly see any such caching done.
Here's what I peeked at (for Qt 5.6):
http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/itemmodels/qabstractitemmodel.cpp#n2601
http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/itemmodels/qabstractitemmodel.cpp#n582I drag the items from another QTreeView .The cast is for that..
Did you mean that?Indeed I did. Have you considered handling the drag/drop events through the ordinary mechanism? Serializing on drag, then deserializing the mime data on drop?
Read and abide by the Qt Code of Conduct
-
However in this case insertRows doesn't do anything so I wonder if there isn't a caching mechanism that avoids to update the view if in fact nothing has changed.
After a quick look (without pretense to be complete) I couldn't clearly see any such caching done.
Here's what I peeked at (for Qt 5.6):
http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/itemmodels/qabstractitemmodel.cpp#n2601
http://code.qt.io/cgit/qt/qtbase.git/tree/src/corelib/itemmodels/qabstractitemmodel.cpp#n582I drag the items from another QTreeView .The cast is for that..
Did you mean that?Indeed I did. Have you considered handling the drag/drop events through the ordinary mechanism? Serializing on drag, then deserializing the mime data on drop?
-
@kshegunov : I mean't view side caching.
@Ratzz currently you are not inserting anything through it. Like @kshegunov suggested, implement the drag and drop through the mechanism provided for model/view classes. It's described here
Interested in AI ? www.idiap.ch
Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct -
@kshegunov : I mean't view side caching.
@Ratzz currently you are not inserting anything through it. Like @kshegunov suggested, implement the drag and drop through the mechanism provided for model/view classes. It's described here
-
@kshegunov said:
Serializing on drag, then deserializing the mime data on drop?
No i have not considered this part.
No i have not considered this part.
Then I suggest you try it out. It may prove to be easier and better behaved than pulling the records directly from the tree widget. As for your current implementation, I'm at a loss why it doesn't work. Maybe the tree view is losing the selection when dragging and the selection model returns no records?
I mean't view side caching.
I see, well I didn't look at the view (obviously) but I suppose it's possible.
Read and abide by the Qt Code of Conduct
-
Hi
I am still wondering. Sorry.
Lets say If I dont have drag&drop.I simply append to my internal list used in model.
How will I tell the view(s) that?
I though dataChanged would do it but not even begin/endInsertRow
does it.Thanks
-
No i have not considered this part.
Then I suggest you try it out. It may prove to be easier and better behaved than pulling the records directly from the tree widget. As for your current implementation, I'm at a loss why it doesn't work. Maybe the tree view is losing the selection when dragging and the selection model returns no records?
I mean't view side caching.
I see, well I didn't look at the view (obviously) but I suppose it's possible.
@kshegunov said:
Maybe the tree view is losing the selection when dragging and the selection model returns no records?
I don't think so because the rowCount is getting updated as and when the new drop takes place.
-
Hi
I am still wondering. Sorry.
Lets say If I dont have drag&drop.I simply append to my internal list used in model.
How will I tell the view(s) that?
I though dataChanged would do it but not even begin/endInsertRow
does it.Thanks
-
On a side note, your rowCount implementation should rather return the size of your TableList, that way it's one less thing to manage.
Interested in AI ? www.idiap.ch
Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct
