Howto swap list of data in a tableview

[wysota]

IMO the easiest solution is to have one model for all your streams and either have a proxy filter model to filter out the things you don't want or to make each stream a top-level item of the view and stream data children of a respective item and then to only set a different index as the root index of the view to show a given stream.

Of course your original approach would have worked too. The problem doesn't seem related to Qt but rather to C++ and indexing a C-array.

[andsun]

Hi, interresting, never heard/thought about either of your suggested solutions, but must try them out. Feels like stream as top level might work best... mainly because I don't understand the proxy filter solution but hope the Qt manual will help.

Agree on point about my solution, must be in my c++ code.

[andsun]

To quit the thread with an answer
What I wanted to do is not supported, as I can find out about from "Advanced-Qt-Programming-Creating-Great-Software-with-Cpp-and-Qt-4".

Tree models work in terms of parents and children, where an item’s row is
its position in its parent’s list of children. (In theory, a tree model can be a
recursive tree of tables, but none of Qt’s views supports this.)

However, testing with wysotas suggestion to use QProxyFilter works just fine, only have to add one column with streams to filter on, and hide it. Found example here http://doc.qt.io/qt-5/qsortfilterproxymodel.html
and here as an example http://doc.qt.io/qt-5/qtwidgets-item...l-example.html

Thanks guys -this can be closed for now

[wysota]

What exactly is "not supported"?

[andsun]

Hi wysota,

Haven't tried it out fully yet, but my problem displays where it is not supported, as I understand it.

I don't know for sure but as I got it, the tree model with subitems of tables can't be displayed in, at the time existing Views like QTreeView.
This is where my problem lays, and why I implemented the proxy filter to get around it.
I filter out the "table" within one single model, instead of fetching a model that holds each table from the array of models.

Make sense? What do you think?

Sorry to say haven't found any newer, good books on the subject (Advanced Qt programming with Qt 5.nn), suggestions on that?

[wysota]

the tree model with subitems of tables can't be displayed in, at the time existing Views like QTreeView.

Why not? QTreeView, as the name suggests, can display tree models. Not that you need that in my opinion, I suggested using root indexes to display a list/table from a tree model.

#include <QtWidgets>
 
int main(int argc, char **argv) {
  QApplication app(argc, argv);
  QWidget w;
  QVBoxLayout *l = new QVBoxLayout(&w);
  QComboBox *cb = new QComboBox;
  l->addWidget(cb);
  QListView *view = new QListView;
  l->addWidget(view);
  QStandardItemModel model;
  for(int s=0;s<10;++s) {
    QStandardItem *stream = new QStandardItem(QString("Stream %1").arg(s+1));
    int cnt = qrand() % 20;
    for(int e = 0; e < cnt; ++e) {
      QStandardItem *item = new QStandardItem(QString("Entry %1 of stream %2").arg(e+1).arg(s+1));
      stream->appendRow(item);
    }
    model.appendRow(stream);
  }
 
  view->setModel(&model);
  cb->setModel(&model);
  view->setRootIndex(model.index(cb->currentIndex(), 0));
  QObject::connect(cb, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), [&](int idx) { view->setRootIndex(model.index(idx, 0)); });
  l->addWidget(new QLabel("Full model:"));
  QTreeView *tview = new QTreeView;
  l->addWidget(tview);
  tview->setModel(&model);
  w.show();
  return app.exec();
}

#include <QtWidgets>

int main(int argc, char **argv) {
  QApplication app(argc, argv);
  QWidget w;
  QVBoxLayout *l = new QVBoxLayout(&w);
  QComboBox *cb = new QComboBox;
  l->addWidget(cb);
  QListView *view = new QListView;
  l->addWidget(view);
  QStandardItemModel model;
  for(int s=0;s<10;++s) {
    QStandardItem *stream = new QStandardItem(QString("Stream %1").arg(s+1));
    int cnt = qrand() % 20;
    for(int e = 0; e < cnt; ++e) {
      QStandardItem *item = new QStandardItem(QString("Entry %1 of stream %2").arg(e+1).arg(s+1));
      stream->appendRow(item);
    }
    model.appendRow(stream);
  }
  
  view->setModel(&model);
  cb->setModel(&model);
  view->setRootIndex(model.index(cb->currentIndex(), 0));
  QObject::connect(cb, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged), [&](int idx) { view->setRootIndex(model.index(idx, 0)); });
  l->addWidget(new QLabel("Full model:"));
  QTreeView *tview = new QTreeView;
  l->addWidget(tview);
  tview->setModel(&model);
  w.show();
  return app.exec();
}

To copy to clipboard, switch view to plain text mode 

[andsun]

Hi, thks for code sample
Think I'm too inexperianced here though. don't get

QObject::connect(cb, static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChang ed), [&](int idx) { view->setRootIndex(model.index(idx, 0)); });

Guess somehow explained(?) in the old style that I grasp/still use ... and in pseudo stylish it means like:
connect ( cboBox, SIGNAL( currentIndexChanged(int idx)), treeView, SLOT( treeView->SetRootIndex(int idx)))

[ChrisW67]

This line uses the Qt5 new-style connect() and a C++11 lambda function in place of a named slot function.

QObject::connect(
  cb,    
  //^^^ sender object
  static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged),   
  //^^^ a PointerToMemberFunction for the currentIndexChanged(int) signal function and not the currentIndexChanged(QString) one
  [&](int idx) { view->setRootIndex(model.index(idx, 0)); }  
  //^^^ a C++11 lambda function accepting an int argument (Functor)
);
 
// equivalent to the traditional Qt
 
connect(
  cb,
  SIGNAL(QComboBox::currentIndexChanged(int)),
  SLOT(someSlot(int))
);
 
// with a slot function
void someSlot(int idx) {
  view->setRootIndex(model.index(idx, 0)); 
}

QObject::connect(
  cb,    
  //^^^ sender object
  static_cast<void (QComboBox::*)(int)>(&QComboBox::currentIndexChanged),   
  //^^^ a PointerToMemberFunction for the currentIndexChanged(int) signal function and not the currentIndexChanged(QString) one
  [&](int idx) { view->setRootIndex(model.index(idx, 0)); }  
  //^^^ a C++11 lambda function accepting an int argument (Functor)
);

// equivalent to the traditional Qt

connect(
  cb,
  SIGNAL(QComboBox::currentIndexChanged(int)),
  SLOT(someSlot(int))
);

// with a slot function
void someSlot(int idx) {
  view->setRootIndex(model.index(idx, 0)); 
}

To copy to clipboard, switch view to plain text mode