Signal for QStringList count changed?

[lansing]

I have a QStringList storing a bunch of names and QcomboBox to populate the list. I'll be adding new QString to the list and at the end of process, I want the QcomboBox to update with the list. But I couldn't find a signal for count change.

connect(m_stringlist, &QStringList::countChanged??, this, &slotHandleCountChange );

[mrjj]

Hi
QStringList has zero signals.
Maybe you could use
https://doc.qt.io/qt-5/qstringlistmodel.html

Or simply define a new signal in the holding class and emit that to make combobox do what its needs to do.

[lansing]

@mrjj

Hi what would be the signal if I'm to use QStringListModel?

[SGaist]

Hi,

No signal needed, update the content of the model and the changes will be propagated to the view.

[mrjj]

@lansing
Hi
Actually it's then a real model
and would signal the comboBox by itself if
the model is changed.
So you would just change the model and it would be auto-updated.

Heh. one sec too late :)

[mrjj]

Hi
Just a mini sample since we work directly with a model

 // make the model
    QStringListModel *mo = new QStringListModel;
    // stuff something in it
    mo->setStringList( QStringList() << "a" << "b" );
    // assign the model to the combobox
    ui->comboBox->setModel(mo);
    // use helper function to add string to the end of the model
    AddString(mo,"hi");
    AddString(mo,"there");
    AddString(mo,"im a model");
...

void AddString(QAbstractItemModel *model, QString newString )
{
    if(model->insertRow(model->rowCount())) {
           QModelIndex index = model->index(model->rowCount() - 1, 0);
           model->setData(index, newString);
       }
}

[lansing]

@mrjj said in Signal for QStringList count changed?:

void AddString(QAbstractItemModel *model, QString newString )

Wow looks like it would be better for me to create a subclass of qstringlistmodel to put all these in because I'm probably going to need more functions for this such as removeString.

[mrjj]

@lansing
yes thats not bad idea to wrap in a class to keep it contained.

[lansing]

@mrjj

I encountered a problem when creating the subclass. When I created a new item model class in Qt Creator, it asks me to reimplement all the basic functions...

[mrjj]

@lansing
Hi
In what way, don't you inherit qstringlistmodel ?

[lansing]

@mrjj

Oh I was creating the class with the default one from the wizard, which was inheriting the abstactitemmodel. Manually declaring the classs solved it.

void GenericStringListModel::append(QString &a_string)
{
    if (insertRow(rowCount())) {
        QModelIndex index = this->index(rowCount() - 1, 0);
        setData(index, a_string);
    }
}

I'm not sure if using this is correct because it's giving me error without it.

And is this correct for remove string from the list model?

void GenericStringListModel::removeOne(QString &a_string)
{
    int index = stringList().indexOf(a_string);
    removeRow(index);
}

[mrjj]

@lansing
hi
Hmm i wonder what it saw for index without "this". however if
it works with it. then no harm.

Looks good. The removeRow should emit the right signals.

[JKSH]

@lansing said in Signal for QStringList count changed?:

    QModelIndex index = this->index(rowCount() - 1, 0);

...

I'm not sure if using this is correct because it's giving me error without it.

You defined a new local variable called index. That conflicts with name of the function index(). That's why you need this to tell the compiler to use the function instead of the variable.

If you gave your variable a different name, then you don't need this.

[mrjj]

@JKSH
doh. Good catch :)