Combobox in Qtableview

[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));

[n-2204]

@VRonin
It's because you recreate the entire list every time. You should just add/remove only the items that changed
okay,, ya I'm using dataChanged signal , so i think whenever changes in table1 col0 values so combobox selection got affect

connect(ui.tableView->model(), &QAbstractItemModel::dataChanged, this,
&tool::rowvalue1);

So need to change in SIGNAL or anycondition to be add?
but I need to update data in combobox so datachanged signal must be used.
need to give condition in combobox ? or in SLOT something need to change or what else ??

[VRonin]

Instead of just doing

combo->model()->removeRows(0,combo->count(),combo->rootModelIndex()); // remove all items from the combo
combo->addItems(guesslist);  //add list to combobox

iterate over the items in the combo, remove those that don't appear in guesslist and add those that appear in guesslist but are not already in the combo

[n-2204]

to remove duplicates

guesslist.removeDuplicates(); // clear duplicates
guesslist.removeAll(QString(""));
combo->model()->removeRows(0,combo->count(),combo->rootModelIndex()); // remove all items from the combo
combo->addItems(guesslist);  //add list to combobox

remove those that don't appear in guesslist
--means using removerows() all items are removed everytime so this need to change ??

[VRonin]

@n-2204 said in Combobox in Qtableview:

all items are removed everytime so this need to change ??

Correct

[n-2204]

@VRonin Is removeItem() can be used ?

[n-2204]

@VRonin said in Combobox in Qtableview:
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 is always updated,

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
        }
        colvallist1.removeDuplicates(); // strip dubs clear dublicates
        colvallist1.removeAll(QString(""));
        combo->setPlaceholderText(QString(" "));

        combo->addItems(guesslist); // adding gueslist will add item value everytime so no need to pass this right ??
combo->removeItem(); 

iterate over the items in the combo, remove those that don't appear in guesslist and add those that appear in guesslist but are not already in the combo

item should store in another Qstringlist and then check with initial list ?

[n-2204]

edited
In prev code i add these code lines, and now selection not changed when added new items in tableview column and updating in col combobox values

 for (int i = 0; i < guesslist.count(); i++) 
        {
            if (combo->findText(guesslist[i]) != -1)//-1 means "not found"
            { 
                continue;
            }
            else {
                combo->addItem(guesslist[i]); //Add to QCombobox
            }

but not able to apply for "remove those t don't appear in guesslist (when col1 row values chnaged)" ??

[JonB]

@n-2204
So you have to one of:

• Have another loop/iterator through all the items which are in the combo box and remove any which are not in the guess list now; or
• Clear out all the items in the combo box first, and then only add back in those which are now in guess list.

[n-2204]

@JonB said in Combobox in Qtableview:

Clear out all the items in the combo box first, and then only add back in those which are now in guess list.

when i'm clearing all first then, whatever my prev selection in combobox it will be gone 
 combo->clear();

Have another loop/iterator through all the items which are in the combo box and remove any which are not in the guess list now

tried this but not working correctly where to chnge ?,when I'm changing value in guesslist then the combo selection got changed

  QStringList itemsInComboBox;
            for (int index = 0; index < guesslist.count(); index++)
            {
                itemsInComboBox << combo->itemText(index);
                if ( guesslist[index]!=itemsInComboBox[index] )
                    combo->removeItem(index); 
            }