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QCheckBox's not changing state?

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  • S Offline
    S Offline
    SRaD
    wrote on 24 Mar 2019, 18:03 last edited by
    #1

    Does anyone see anything wrong w/ how I'm changing the states of my QCheckBox's, rather, how they're not changing? My checkboxes appear checked, but I am unable to change them to unchecked.

    QVariant MyTreeModel::data(const QModelIndex &index, int role) const
    {
        QModelIndex parent = index.parent();
        QModelIndex child = index.sibling(parent.row(), parent.column());
    
        if (!index.isValid())
            return QVariant();
    
        MyTreeItem *item = static_cast<MyTreeItem *>(index.internalPointer());
    
        if (role == Qt::CheckStateRole) {
            if (parent.row() == 0 && index.column() == 0)
                return static_cast<int>(item->getChecked() ? Qt::Checked :
                    Qt::Unchecked);
        }
    
        if (role != Qt::DisplayRole) 
            return QVariant();
    
        return item->data(index.column());
    }
    
    bool MyTreeModel::setData(const QModelIndex &index,
        const QVariant &value, int role)
    {
        QModelIndex parent = index.parent();
    
        if (role != Qt::EditRole && role != Qt::CheckStateRole)
            return false;
    
        MyTreeItem *item = getItem(index);
    
        bool result;
    
        if (role == Qt::CheckStateRole) {
            if (parent.row() == 0 && index.column() == 0) {
                bool chk = (item->getChecked() ? Qt::Unchecked : Qt::Checked);
    
                item->setChecked(chk);
    
                result = item->setData(index.column(), chk);
            }
        }
        else
            result = item->setData(index.column(), value);
    
        if (result)
            emit dataChanged(index, index, {role});
    
        return result;
    }
    
    J 1 Reply Last reply 24 Mar 2019, 18:27
    0
    • S SRaD
      24 Mar 2019, 18:03

      Does anyone see anything wrong w/ how I'm changing the states of my QCheckBox's, rather, how they're not changing? My checkboxes appear checked, but I am unable to change them to unchecked.

      QVariant MyTreeModel::data(const QModelIndex &index, int role) const
      {
          QModelIndex parent = index.parent();
          QModelIndex child = index.sibling(parent.row(), parent.column());
      
          if (!index.isValid())
              return QVariant();
      
          MyTreeItem *item = static_cast<MyTreeItem *>(index.internalPointer());
      
          if (role == Qt::CheckStateRole) {
              if (parent.row() == 0 && index.column() == 0)
                  return static_cast<int>(item->getChecked() ? Qt::Checked :
                      Qt::Unchecked);
          }
      
          if (role != Qt::DisplayRole) 
              return QVariant();
      
          return item->data(index.column());
      }
      
      bool MyTreeModel::setData(const QModelIndex &index,
          const QVariant &value, int role)
      {
          QModelIndex parent = index.parent();
      
          if (role != Qt::EditRole && role != Qt::CheckStateRole)
              return false;
      
          MyTreeItem *item = getItem(index);
      
          bool result;
      
          if (role == Qt::CheckStateRole) {
              if (parent.row() == 0 && index.column() == 0) {
                  bool chk = (item->getChecked() ? Qt::Unchecked : Qt::Checked);
      
                  item->setChecked(chk);
      
                  result = item->setData(index.column(), chk);
              }
          }
          else
              result = item->setData(index.column(), value);
      
          if (result)
              emit dataChanged(index, index, {role});
      
          return result;
      }
      
      J Offline
      J Offline
      JonB
      wrote on 24 Mar 2019, 18:27 last edited by JonB
      #2

      @SRaD
      I have no idea whether it has any relevance to your problem. But in setData() how is result set to anything if it's CheckStateRole and you are not on row == column == 0? Do you not get a compiler warning for "possibly uninitialized variable used"?

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      • C Offline
        C Offline
        Christian Ehrlicher
        Lifetime Qt Champion
        wrote on 24 Mar 2019, 18:35 last edited by
        #3

        Is MyTreeItem derived from QTreeWidgetItem? If so I don't see a need to reimplement setData() at all.

        Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
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        • S Offline
          S Offline
          SRaD
          wrote on 24 Mar 2019, 19:58 last edited by
          #4

          No. MyTreeItem is just a class. I used the example just like TreeItem from here ... https://doc.qt.io/qt-5/qtwidgets-itemviews-editabletreemodel-example.html

          And the model is derived from QAbstractItemModel.

          J 1 Reply Last reply 24 Mar 2019, 20:38
          0
          • S SRaD
            24 Mar 2019, 19:58

            No. MyTreeItem is just a class. I used the example just like TreeItem from here ... https://doc.qt.io/qt-5/qtwidgets-itemviews-editabletreemodel-example.html

            And the model is derived from QAbstractItemModel.

            J Offline
            J Offline
            JonB
            wrote on 24 Mar 2019, 20:38 last edited by JonB
            #5

            @SRaD
            OK, apart from what I said before which I think you ought address, your logic in your setData() is wrong in the role == Qt::CheckStateRole && parent.row() == 0 && index.column() == 0 case.

                        bool chk = (item->getChecked() ? Qt::Unchecked : Qt::Checked);
            
                        item->setChecked(chk);
            
                        result = item->setData(index.column(), chk);
            

            You set the chk you'll use as a reverse of the current item->getChecked(), i.e. it toggles each time it's called; and you pass that on to setChecked/setData(). But you're supposed to be using the value parameter to your setData(), which you're ignoring here, like you do in the else result = item->setData(index.column(), value); case. Your current checked/unchecked behaviour depends on how many times setData() happens to be called, or that it will only get called when it's time to toggle the check, both of which are quite wrong.

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            • S Offline
              S Offline
              SRaD
              wrote on 31 Mar 2019, 19:59 last edited by SRaD
              #6

              @JonB
              So I changed the logic to this, but I find that setData() isn't being called. The checkboxes do show up, so my model is in place, but I don't understand why this isn't called when I click on the items.

              bool MyTreeModel::setData(const QModelIndex &index,
              const QVariant &value, int role)
              {           
                  QModelIndex parent = index.parent();
              
                  std::cout << "value.toInt = " << value.toInt() << std::endl;
              
                  if (role != Qt::EditRole && role != Qt::CheckStateRole)
                      return false;
                      
                  MyTreeItem *item = getItem(index);
                  
                  bool result;
              
                  if (role == Qt::CheckStateRole && (parent.row() == 0 && 
                          index.column() == 0)) {
                  
                      Qt::CheckState state = static_cast<Qt::CheckState>(value.toInt());
                  
                      // logic probably still isn't correct here, but i'm concerned with why it's not called
                      bool check = (state == Qt::Checked);
                      //item->setChecked(chk);
                   
                      result = item->setData(index.column(), check);
                  }
                  else  
                      result = item->setData(index.column(), value);                         
                                                                                         
                  if (result)
                      emit dataChanged(index, index, {role});                                
              
                  return result;
              }
              
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              • C Offline
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                Christian Ehrlicher
                Lifetime Qt Champion
                wrote on 31 Mar 2019, 20:49 last edited by
                #7

                What does your item->getChecked() look like?
                And do you really store try to store the check state and the edit role in one place?
                --> item->setData(index.column(), check);

                Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
                Visit the Qt Academy at https://academy.qt.io/catalog

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                • S Offline
                  S Offline
                  SRaD
                  wrote on 31 Mar 2019, 21:22 last edited by
                  #8

                  @Christian-Ehrlicher
                  My getChecked looks like the following:

                  bool MyTreeItem::getChecked() const
                  {
                      return checked;
                  }       
                  
                  void MyTreeItem::setChecked(bool set)
                  {       
                      checked = set;; 
                  }
                  

                  Not sure about edit role && check state in one place. I thought if it was a checkbox, it had to be editable, and I thought setChecked() is where I needed to store it.

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                  24 Mar 2019, 18:03

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