Combobox in Qtableview

[Christian Ehrlicher]

@n-2204 said in Combobox in Qtableview:

connect(ui.tableView->model(), SIGNAL(rowsInserted), ui.tableView_2->model(), SLOT(changedvalue()));

This is wrong - again: use the new signal/slot syntax to catch such errors on compile time. And if you don't want then watch the output to stdout during debugging!

[JonB]

@Christian-Ehrlicher
I, and you, have repeatedly advised @n-2204 to change from the old macros to the new style, and provided the necessary links (e.g. https://forum.qt.io/topic/126193/spinbox-input-add-rows, I think we posted 4 times there to this effect). Precisely because the user keeps getting the connections wrong. It seems the user is not interested in making the effort to change their ways, and prefers to make the same mistakes and keep posting for others to sort out....

[n-2204]

connect(ui.tableView->model(), &QAbstractItemModel::rowsInserted, this,
&tool::changedvalue);

but signal/slot should work for both the ways
and one thing is there is change in column 1 row values and @VRonin you told to use signal rowinserted() ?

[VRonin]

but signal/slot should work for both the ways

It does but in case you make a mistake the new syntax lets you know straight away when you try to compile and it's not just a warning in the console while the program runs.
Also the new connection is faster

there is change in column 1 row values and @VRonin you told to use signal rowinserted() ?

In that case you would use the conveniently named dataChanged signal

void tool::changedvalue()

please do no rebuild all the widgets everytime something changes. setIndexWidget is already super inefficient, if you keep recreating them your program will probably stutter a lot

[n-2204]

So when i am passing my values in a Qstring that time its coming in combobox but same when i try using table1 column1 rows value that time only last row value is adding in Combobox values looks like all values not appending
Where need to make changes?

connect(ui.tableView->model(), &QAbstractItemModel::dataChanged, this,
          &Gearcycle_model::changedvalue);

void tool::changedvalue() {
QAbstractItemModel* table1 = ui.tableView->model();
QAbstractItemModel* table2 = ui.tableView_2->model();
for (int i = 0, maxI = table2->rowCount();i <= maxI;++i)//combobox in table2 col1
{
    for (int r = 0, maxI = table1->rowCount();r < maxI;++r)//getvalue fromtable1
    {
        QComboBox* combo = new QComboBox();
        //QString list1[10] = { table1->data(table1->index(r, 0)).toString() };//store value in list
        QString list1[4] = { "input 1","input 2","input3","input 4" };
        qDebug() << "table index" << r;
        for (int j = 0; j < 3; j++)
        {
            combo->addItem(list1[j]);
            qDebug() << "combox values" << list1[j];//pass list to combobox
            qDebug() << "list j=" << j;
        }
        ui.tableView_2->setIndexWidget(ui.tableView_2->model()->index(i, 1), combo);
        qDebug() << "row value i=" << i;
    }
}
}

[VRonin]

@n-2204 said in Combobox in Qtableview:

Where need to make changes?

Read your code. The loops are wrong, this is basic C++

[n-2204]

@n-2204 said in Combobox in Qtableview:

So when i am passing my values in a Qstring that time its coming in combobox but same when i try using table1 column1 rows value that time only last row value is adding in Combobox values looks like all values not appending
Where need to make changes?

connect(ui.tableView->model(), &QAbstractItemModel::dataChanged, this,
          &Gearcycle_model::changedvalue);

void tool::changedvalue() {
QAbstractItemModel* table1 = ui.tableView->model();
QAbstractItemModel* table2 = ui.tableView_2->model();
for (int i = 0, maxI = table2->rowCount();i <= maxI;++i)//combobox in table2 col1
{
    for (int r = 0, maxI = table1->rowCount();r < maxI;++r)//getvalue fromtable1
    {
        QComboBox* combo = new QComboBox();
        //QString list1[10] = { table1->data(table1->index(r, 0)).toString() };//store value in list

when passing this that time only last row value is coming in combobox

        QString list1[4] = { "input 1","input 2","input3","input 4" };

this is working when i am passing QString list1[4] = { "input 1","input 2","input3","input 4" }; in combobox

        for (int j = 0; j < 3; j++)
        {
            combo->addItem(list1[j]);
            qDebug() << "combox values" << list1[j];//pass list to combobox
            qDebug() << "list j=" << j;
        }
        ui.tableView_2->setIndexWidget(ui.tableView_2->model()->index(i, 1), combo);
        qDebug() << "row value i=" << i;
    }
}
}

yes, looks like some small change will be needed during addItem in combobox

[VRonin]

Look at the loops of i and r. think about what they are doing, ask yourself when you want to create and populate a combo, inside which loop?

[n-2204]

ya it works thankyou.

void tool::rowvalue1() {
QAbstractItemModel* table1 = ui.tableView->model();
QAbstractItemModel* table2 = ui.tableView_2->model();
for (int i = 0, maxI = table2->rowCount();i < maxI;++i)//combobox in table2 col1
{
     QComboBox* combo = new QComboBox();
      combo->setDuplicatesEnabled(false);
  for (int r = 0, maxI = table1->rowCount();r < maxI;++r)//getvalue fromtable1
      {
         QString list1[10] = { table1->data(table1->index(r, 0)).toString() };//store value in list
       for (int j = 0; j < 1; ++j)
        {

--using uniqueSet trying to add only unique values(no duplicate values) in Combobox but its not working is this correct way ? or any other way to do this ?

            QSet<QString> uniqueSet;
             if (!uniqueSet.contains(list1[j]))//add only unique values in combobox
             {
                uniqueSet.insert(list1[j]);
                combo->addItem(list1[j]);  //add list to combobox  
                qDebug() << " values " << list1[j];
            }
        }
        ui.tableView_2->setIndexWidget(table2->index(i, 1), combo);
    }
  }
}

[VRonin]

@n-2204 said in Combobox in Qtableview:

for (int j = 0; j < 1; ++j)

[n-2204]

no its 10
j<10
using uniqueSet trying to add only unique values(no duplicate values) in Combobox but its not working is this correct way ? or any other way to do this ?

[VRonin]

My feeling is that you have no idea what your code does, you are just copy-pasting stuff around and hoping that it does something.
Once again: read your code, run it step-by-step. This has nothing to do with Qt, it's just about loops

[n-2204]

thanks for your answers

but what i shared i working code
and now i asked -
using uniqueSet trying to add only unique values(no duplicate values) in Combobox but this way not working is this correct way ? or any other way to do this ?

this it might be very simple for you or you are expert but i am new C++ and Qt so i am having so many doubts may be silly.
Thanks

[JonB]

@n-2204 said in Combobox in Qtableview:

no its 10
j<10

No, the code you pasted reads:

 for (int j = 0; j < 1; ++j)

That's 1, not 10. Or are you saying you want help to fix your code but you don't paste the actual code you want help with?

using uniqueSet trying to add only unique values(no duplicate values) in Combobox but this way not working

If your pasted code is to be believed, you seem to declare QSet<QString> uniqueSet; inside the j loop.

            QSet<QString> uniqueSet;
             if (!uniqueSet.contains(list1[j]))//add only unique values in combobox

This will always be true. uniqueSet is always empty.

[mrjj]

Hi

• any other way ?

Well your idea with QSet<QString> uniqueSet; was fine, but the logic/location was not right
and i think QStringList might be easier.

so this would do it. ( i assume you want a combo on each row in table 2 with same non-dub values in the combo)

   QAbstractItemModel *table1 = ui->tableView->model();
    QAbstractItemModel *table2 = ui->tableView_2->model();
    QStringList guesslist;
    for (int r = 0, maxI = table1->rowCount(); r < maxI; ++r) { //for all value rows
        guesslist.append( table1->data(table1->index(r, 0)).toString() );//store value in stringlist
    }
    guesslist.removeDuplicates(); // strip dubs
    for (int i = 0, maxI = table2->rowCount(); i < maxI; ++i) { //for all rows
        QComboBox *combo = new QComboBox(); // make combo
        combo->addItems(guesslist);  //add list to combobox
        ui->tableView_2->setIndexWidget(table2->index(i, 1), combo);// add combo
    }

But a word of warning. If you have many rows then setIndexWidget can become quite heavy for
smaller devices and the app might lag. The cure is using a delegate as fully shown here ( thx VRonin :)

https://forum.qt.io/topic/125906/qtableview-combobox-in-columns/10

This also has the benefit that you don't need to copy anything around. its using the values directly. always updated.

[n-2204]

QStringList might be easier
guesslist.removeDuplicates(); // strip dubs

 Ok Thanks!! but still looks like empty row value is coming in Combobox

if you have many rows then setIndexWidget can become quite heavy for
smaller devices and the app might lag

I am having 6-7 rows in my table

I'm not using delegate as I need to read index, selection and apply some condition based on Combobox values in other columns ...,for some further req.

Thanks

[mrjj]

@n-2204

Hi

• Ok Thanks!! but still looks like empty row value is coming in Combobox

Yes we add empty ones too but you can just dont do that.

for (int r = 0, maxI = table1->rowCount(); r < maxI; ++r) { //for all value rows
   QString str = table1->data(table1->index(r, 0)).toString();
    if ( ! str.IsEmpty() ) 
     guesslist.append( str );//store value in stringlist
    }

https://doc.qt.io/qt-5/qstring.html#isEmpty

[VRonin]

@mrjj said in Combobox in Qtableview:

for (int i = 0, maxI = table2->rowCount(); i < maxI; ++i) { //for all rows
QComboBox *combo = new QComboBox(); // make combo
combo->addItems(guesslist); //add list to combobox
ui->tableView_2->setIndexWidget(table2->index(i, 1), combo);// add combo
}

Slight tweak to avoid recreating the combobox every time:

for (int i = 0, maxI = table2->rowCount(); i < maxI; ++i) { //for all rows
	const QModelIndex idx = table2->index(i, 1);
	QComboBox *combo = qobject_cast<QComboBox*>(ui->tableView_2->indexWidget(idx));
	if(!combo){
		combo = new QComboBox(); // make combo  
		ui->tableView_2->setIndexWidget(idx , combo);// add combo
	}
	combo->model()->removeRows(0,combo->count(),combo->rootModelIndex());
	combo->addItems(guesslist);  //add list to combobox
}

@n-2204 said in Combobox in Qtableview:

I'm not using delegate as I need to read index, selection and apply some condition based on Combobox values in other columns

You can do that with delegates too. Probably even easier.

[n-2204]

@VRonin @mrjj
1.
Actually when I'm using both the ways to add values in Combobox
one thing happening ,if I added some values in column0 table1 then select in combobox and again adding values in table1 Column0 that time combobox selection go away

I am using dataChanged() signal
connect(ui.tableView->model(), &QAbstractItemModel::dataChanged, this,
&tool::rowvalue1);
Is it because of this signal ? how can i prevent this ??

2. As I'm using SLOT::rowvalue1() to add combobox in Qtableview
   now how can i take index() of combobox as there is SIGNAL::QComboBox::currentIndexChanged, , so again I need to write SLOT for index
   void tool::IndexChanged(int index)
   {
   combo->setCurrentIndex(combo->currentIndex());
   //but combo will be inaccessible here ??
   }
   connect(combo, QOverload<int>::of(&QComboBox::currentIndexChanged), this,
   &tool::IndexChanged);
   Is this correct way ?

[VRonin]

@n-2204 said in Combobox in Qtableview:

Is it because of this signal ? how can i prevent this ??

It's because you recreate the entire list every time. You should just add/remove only the items that changed

---

You can use std::bind to forward the combo to the slot

void IndexChanged(int index, QComboBox* combo){
/// do stuff
}

connect(combo, QOverload<int>::of(&QComboBox::currentIndexChanged), this, std::bind(&tool::IndexChanged, this, std::placeholders::_1, combo));