Get previous value of QComboBox, which is in a QTableWidget, when the value is changed

Say I have a QTableWidget and in each row there is a QComboBox and a QSpinBox. Consider that I store their values is a QMap<QString /*Combo box val*/,int /*spin box val*/> theMap;

When comboBoxes value or spin boxes value is being changed I want to update theMap. So I should know what was the former value of the combo box in order to replace with the new value of the comboBox an开发者_StackOverflow社区d also take care of the value of the spin box.

How can I do this?

P.S. I have decided to create a slot that when you click on a table, it stores the current value of the combo box of that row. But this works only when you press on row caption. In other places (clicking on a combobox or on a spinbox) itemSelectionChanged() signal of QTableWidget does not work.

So in general my problem is to store the value of the combo box of selected row, and the I will get ComboBox or SpinBox change even and will process theMap easily.

How about creating your own, derived QComboBox class, something along the lines of:

class MyComboBox : public QComboBox
{
  Q_OBJECT
private:
  QString _oldText;
public:
  MyComboBox(QWidget *parent=0) : QComboBox(parent), _oldText() 
  {
    connect(this,SIGNAL(editTextChanged(const QString&)), this, 
        SLOT(myTextChangedSlot(const QString&)));
    connect(this,SIGNAL(currentIndexChanged(const QString&)), this, 
        SLOT(myTextChangedSlot(const QString&)));
  }
private slots:
  myTextChangedSlot(const QString &newText)
  {
    emit myTextChangedSignal(_oldText, newText);
    _oldText = newText;
  }
signals:
  myTextChangedSignal(const QString &oldText, const QString &newText);  
};

And then just connect to myTextChangedSignal instead, which now additionally provides the old combo box text.

I hope that helps.

A bit late but I had the same problem and solved in this way:

class CComboBox : public QComboBox
{
   Q_OBJECT

   public:
      CComboBox(QWidget *parent = 0) : QComboBox(parent) {}


      QString GetPreviousText() { return m_PreviousText; }

   protected:
      void mousePressEvent(QMouseEvent *e)
      { 
         m_PreviousText = this->currentText(); 
         QComboBox::mousePressEvent(e); 
      }

   private:
      QString m_PreviousText;
};

My suggestion is to implement a model, which would help you make a clean separation between the data, and the UI editing the data. Your model would then get notified that a given model index (row and column) changed to the new data, and you could change whatever other data you needed to at that point.

I was just having a similar issue, but for me i needed the previous index for something very trivial so defining and implementing a whole class for it was unjustified.

So what I did instead was keep an argument called say 'previousIndex' and updated it's value only after I had done everything I needed with it