What model are you using? QStandardItemModel had the roles argument working from Qt 5.11 onward. An empty role vector implies "all roles changed"

@Athius
Sure it works, here my code for a bookmark tree:

bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) { Q_UNUSED(column) if(action EQ Qt::IgnoreAction) return false; if(action EQ Qt::MoveAction) { QByteArray bytes=data->data(MIME_Bookmark); QDataStream stream(&bytes,QIODevice::QIODevice::ReadOnly); qintptr i; int r,c; stream>>i>>r>>c; QModelIndex index=createIndex(r,c,i); moveRow(index,index.row(),parent,row); } return true; }

Of course you need to create and return your custom data in mimeData () as well.

@raven-worx I don't use any custom item delegate.

My model doesn't update, its items are fixed.

@VRonin: Ok, updated to 5.10.1

Then you have to propagate the information when your underlying data changes.

I'm sorry but I still don't get how you would like it to look

@SGaist

Thank you for your clarification on the behaviour of QTableView.

Your description implies there should actually be 3 queries against the data, then. I only see 2. However, I admit I would need more time to be sure.

Let me see if I have understood the behaviour of setSortingEnabled() & sortByColumn():

setSortingEnabled() is what makes the View show sort indicators on column headers and allow clicking. It also executes a data fetch query, passing whatever (if anything) is currently defined as the sort order (from sortByColumn()) into an ORDER BY. sortByColumn() determines the ORDER BY. It too executes a data fetch.

(Please correct me if I am wrong.) Now, after (just, i.e. no sortByColumn() yet) a setSortingEnabled() I will see the sort indicator in some direction on some column. I am guessing this would be Ascending on column #0 initially(?) However, the query it issues has no ORDER BY at all, so by definition the rows are in indeterminate order. This seems simply inconsistent to me.

What I would have expected/hoped is that setSortingEnabled() would have passed an ORDER BY col0 ASC if that is how the data is supposed to be sorted to correspond to the initial sort indicator state, and/or an optional parameter to allow specification of the initial sort order desired in the View and to be passed in the initial query --- in effect, combining the setSortingEnabled() with an initial sortByColumn(). Or even, as you say, an equivalent of QSqlTableModel.setSort(). As it stands it seems you must fetch the data twice simply to correspond to the View's initial state.

I have inherited 32K lines of code which uses every kind of Qt SQL/model/view architecture all over the place, it's a mess. I will indeed investigate QSortFilterProxyModel. I don't mind which code I use to achieve it, I just don't expect any necessity to fetch the data multiple times for the initial situation.

rather than the delegate I'd reimplement QTreeView:
protected:

virtual void drawBranches(QPainter *painter, const QRect &rect, const QModelIndex &index) const virtual void drawRow(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const

and slots

void collapse(const QModelIndex &index) void expand(const QModelIndex &index)

But agree is not straightforward and will require some work

Thank you for your suggestion. I think it's what I'll eventually settle for, fairly easy to indeed, using just one SQL query.
Although, I'm starting to think ... wouldn't my original aim be easier to fulfil using TreeWidget and not TreeView?

Hello guys. Thanks for your answerS.
The "error" was simple, stupid. In fact the _manageOrderedTable is an instance of a class called ManageOrderedTable which inherits from QTableWidget.
In this class, there's a method called fillAll and I called setColumnCount() from there. Bad idea.
When I call this method from upon the for loop, everything is fine. I don't understand why.
I could understand if setColumnCount() were called too late, but in this case I should have a segfault, trying to call a cell that doesn't exist.
Well, I don't really understand why but now it works...

Tank you for your help, Patrick.

@michalos I'm not sure if I can help you but seems like model test code works for me.

What I did:

Added modeltest.h and cpp into my project Added "testlib" into "QT" section of project file Added this to modeltest.h: #include <QtTest/qtestcase.h> #define qVariantCanConvert(_type_, _var_) _var_.canConvert(QMetaType::_type_) Changed expressions like "qVariantCanConvert<QString> ( variant)" to "qVariantCanConvert(QString, variant)" in modeltest.h

And... my sample model failed to pass the test of course :D

Ok. I've found the answer.

I subclass the QTreeView and override the void resizeEvent(QResizeEvent* e) as shown:

void MyTreeView::resizeEvent(QResizeEvent *e) { if(model() != Q_NULLPTR){ model()->layoutChanged(); } QTreeView::resizeEvent(e); }

And it did the trick.

Had help from the Voidrealms Facebook group.

@Yohdu said:

My second and main question is then : how to implement correct drag and drop operations with custom QStandardItem which needs to own custom data ?

With the standard item widgets/models you can't drag-n-drop custom item roles.
This makes sense, since the model doesn't know which UserRole+ was set.
It would need to iterate all possible item-role values when creating the drop-data.

The only solution i see is to create your own custom model and reimplement the needed drag-n-drop methods. This also give you full control over your data structure storing the data inside the model.
This is more work, but you will learn a lot and gain some performance (by avoiding the standard-item classes)

@Joel-Bodenmann said:

How can I make this work with my own delegates?

each index can max only have 1 delegate. Thus you need to merge the code into your own delegate.
Since you also receive a QModelIndex in the most methods of the delegate you need to check the column there.

@NIXIN

class MySortFilterProxyModel : public QSortFilterProxyModel { Q_OBJECT Q_PROPERTY(bool FilterEnabled READ isFilterEnabled WRITE setFilterEnabled ) public: virtual bool filterAcceptsRow(int source_row, const QModelIndex & source_parent) const { if( !m_IsFilterEnabled ) return true; // your filtering code here } bool isFilterEnabled() const { return m_IsFilterEnabled }; void setFilterEnabled( bool enabled ) { if( m_IsFilterEnabled != enabled ) { m_IsFilterEnabled = enabled; this->invalidate(); } } private: bool m_IsFilterEnabled;

Problem Solved.

CODE

QModelIndex index2=proxymodel->mapToSource(index); //Returns the source model index (In my case it was QFileSystemModel) QString selectedrow=filemodel->fileInfo(index2).absoluteFilePath(); //filemodel is My QFileSystem Model.

Hi,

Apply the same filter you are using for your single folder version except that this time rather than using a QString you should keep a QStringList of the folders you want to show and use that.

That wasn't really clear from your original description.

In that case, use a filter. QSortFilterProxyModel for example

Someone on stackoverflow was kind enough to point out my error. My parent method() should have been:

QModelIndex MyModel::parent(const QModelIndex &index) const { if (!index.isValid()) { return QModelIndex(); } QObject *item = (QObject *)index.internalPointer(); Directory *parentItem = qobject_cast<Directory *>(item->parent()); if (!parentItem || parentItem == invisibleTopLevelDirectory()) { return QModelIndex(); } Directory *parentOfParentItem = qobject_cast<Directory *>(parentItem->parent()); if (!parentOfParentItem) { return QModelIndex(); } int listIndex = parentOfParentItem->indexOfItem(parentItem); if (listIndex < 0) { return QModelIndex(); } else { return createIndex(listIndex, index.column(), parentItem); } }

Hi,

Can you provide a minimal compilable example that shows that behavior ?

One possibility might be to use directoryLoaded.

I don't know if there are any Qt models that support SQL for trees. I think they were all built for tables so you might have to build one yourself.
Have you checked out the Simple Tree Model example? I found it pretty helpful: http://doc.qt.io/qt-5/qtwidgets-itemviews-simpletreemodel-example.html . Also, if you find it easier, you can use a QStandardItemModel instead of a QAbstractItemModel.

@mmoerdijk
since Qt 5.10 there is a recursiveFilteringEnabled property on a QSortFilterProxyModel, which does exactly this.

This issue is now resolved. It turned out to be a problem in the model: I forgot to tell the root (invalid parent) to accept drops too. This is done in the QAbstractItemModel::flags() implementation.
The incorrect version was:

Qt::ItemFlags MyModel::flags(const QModelIndex& index) const { if (!index.isValid()) { return 0; } return Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsDropEnabled; }

While this is how it should look like to allow drops in the root (to add new items without a parent):

Qt::ItemFlags MyModel::flags(const QModelIndex& index) const { if (!index.isValid()) { return Qt::ItemIsDropEnabled; // Allow drops in the top-level (no parent) } return Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsDropEnabled; }

Cool, Thanks for all the insite: I have solved the problem with a little more testing.
For the sake of completeness and for others Ive included my code:

void DialogStructureXML::on_btn_add_toroot_released() { QModelIndex currentIndex = ui->tree->selectionModel()->currentIndex(); QModelIndex rootIndex = ui->tree->rootIndex(); QModelIndex traceIndex = currentIndex; QModelIndex child = currentIndex; tree_model *model = (tree_model*) ui->tree->model(); int rowCount = model->rowCount(); int currentRow = 0; int prevRow = 0; //some string cleanup QString ItemText = ui->edit_textvaluefortree->text() ; ItemText.simplified(); //If its a valid index (ie: valid something in the GUI tree) trace back to the parent if ( traceIndex.isValid() ) { while ( traceIndex.isValid() ) { currentRow = traceIndex.row()+1; traceIndex = model->parent(traceIndex); } } if (!model->insertRow(currentRow, rootIndex)) return; child = model->index(currentRow, 0, rootIndex); //Column index 0 model->setData(child, QVariant( ItemText ), Qt::EditRole); return; }

@kshegunov

Since I already worked with the graphics framework, I will stick with it!
Thank you both for your posts. It saved me a lot of time trying ;)

solved

Sounds pretty crazy...

Hi @Joel-Bodenmann
Have you got any solution/feedback for your question?

@kshegunov
Thanks for your reply.
Yes retrieving the child model via child and then setting data worked for me .

Hi,

To add to @mrjj, the styles are free to ignore the palette or certain elements of the palette.

@kshegunov thanks :D

I finally managed to get custom colors. I gave my QTreeView an object name to be able to write this in CSS:

m_treeView->setObjectName("MyTreeView"); m_treeView->setStyleSheet("QTreeView#MyTreeView::item {color: none;}");

basically now my model controls text color through Qt::ForegroundRole regardless of the application's CSS.
I feel like it's the wrong place to put theming, but it works for me at the moment.
Well... until we decide to have different themes :-°

Thanks everybody

Well, I found solution. It is very simple, all I need is to set default drop action for my view class as Qt::MoveAction and return copy and move in the suporrtedDropActions().

Hi, welcome to Devnet.

The things you have to understand with hierarchical model are:

everything can be done through items use appendRows (or insertRows) to add one line containing several columns create a hierarchy on the item that represents the first column with the above appendRows (for instance on "(fffe,e000)" but not on "SQ") use appendRows (or insertRows) on top level instances only to your model (for instance "(0040,a493)" "CS", "(0040,a504)" "SQ", but not "(0008,0105)" "CS")

To view your hierarchy, create a QTreeView and give it this model.

If it's not clear enough, just let me know.

The dummy child is the culprit. It did not set the parent so the parent is invalid.

Technically the "last number of columns" is rather a model specific data. Since that part can change, the model should check the last value and then emit the signal accordingly.

The section ordering part, on the other hand, is indeed view specific data and the model shouldn't do anything with them.

The thing is, that i need this dots to be separate items, since they are used as clickable buttons. I tried to inherit from QTreeView and override drawRow, but when i do that, i need to override visualRect, indexAt and some other methods too, and that's realy inconvenient. Is there another way to reach my goals with QTreeView , or do i need to inherit from QAbstractItemView, and implement this kind of TreeView myself?