How to grey out items in a QTableview delegate editor

[cdontheqt]

Hey , I am writing a setlist application in Qt C++ and have come across a couple of things I can't seem to find out how to do (Excuse me for messy code and if I am missing some basics as I am not a programmer! Any tips/criticism are/is welcome!);

I have a dialog which I display some QTableviews in a QTabwidget (linked to SQLite DB with QSqlRelationalTableModels)
In one tab I have a 'Column' tab where I have checkboxes to select the Columns I will want to output to the setlist. In another tab I have a 'SortBy' value that the outputted list will be sorted by.
So, obviously if I have a particular column unticked then I want to avoid that column being selected in the other tab so I would like the unticked items to be greyed out, I still want to be able to see them but not select them. Can anyone give me some tips on how to do this? I have tried a few things and googled without success! Appreciate any help!

I have used a standard delegate on the tableviews to allow editing.
On the 'SortBy' column, I created a custom delegate to try to do it.
I send the columns that are unticked into the delegate in a Qlist. In this delegate I tried to get the model from the combobox (from the delegate editor, as this is what Google told me to do!!!) but the program crashes)

##Dialog class

#include "settingsdialogclass.h"
#include "ui_settingsdialogclass.h"
#include "proxymodelcheckboxes.h"
#include "constants.h"
#include <customdelegate.h>
#include "customdelegatecombobox.h"

#include <QTableView>
#include <QMessageBox>
#include <QComboBox>
#include <QSpinBox>
#include <QLabel>
#include <QSqlRelationalDelegate>
#include <QDebug>


SettingsDialogClass::SettingsDialogClass(QStringList columnsToHide, QWidget *parent) :
   QDialog(parent),
   ui(new Ui::SettingsDialogClass)
{
   ui->setupUi(this);

   m_modelColumns = new QSqlRelationalTableModel;
   m_modelSections = new QSqlRelationalTableModel;

   m_columnsToHide = columnsToHide;

   ui->tabWidget->addTab(columnTab(),SETTINGS_COLUMN_TAB_NAME);
   ui->tabWidget->addTab(sectionsTab(),SETTINGS_SECTION_TAB_NAME);

   setWindowTitle(SETTINGS_DIALOG_NAME);

   //This loop removes the 2 default tabs (Note once you remove first tab indexes change)
   for (int i=0;i<2;i++)
   {
       ui->tabWidget->removeTab(0);
   }

}

SettingsDialogClass::~SettingsDialogClass()
{
   delete ui;
}


//Tabs
QWidget *SettingsDialogClass::columnTab()
{
   QString tableName = SETTINGS_TABLE_COLUMNS;
   QTableView *settingsViewColumns = new QTableView;;

//****** Proxy Model for checkboxes
   ProxyModelCheckboxes *proxyModel = new ProxyModelCheckboxes;
   QList<bool> boolColumns;

   boolColumns.append(SETTINGS_COLUMN_ONOFF); //Sets the column which will have the checkboxes
   proxyModel->setParameters(boolColumns);


   proxyModel->setSourceModel(m_modelColumns);
   settingsViewColumns->setModel(proxyModel);
//****** Proxy Model for checkboxes


////*****  Standard Model *****//
//    settingsViewColumns->setModel(m_modelColumns);
////*****  Standard Model *****//


   m_modelColumns->setTable(tableName);
   m_modelColumns->setEditStrategy(QSqlTableModel::OnFieldChange);
   m_modelColumns->select();

   QWidget *newTab = new QWidget;

   QVBoxLayout *mainLayout = new QVBoxLayout;
   mainLayout->addWidget(settingsViewColumns);
   newTab->setLayout(mainLayout);

   return newTab;

}

QWidget *SettingsDialogClass::sectionsTab()
{
   QString tableName = SETTINGS_TABLE_SECTIONS;
   QTableView *settingsViewSections = new QTableView;;


   QSqlRelationalTableModel *model = new QSqlRelationalTableModel;

   setSectionsModel(model);

   model->setTable(tableName);
   model->setEditStrategy(QSqlTableModel::OnFieldChange);
   // need to set this to change immediately so I can check if that column is ticked or not
   // The problem is that when you change it then press ok to close the window there is no field change


   model->setRelation(1,QSqlRelation(SETTINGS_TABLE_SECTIONS_INTEGERS,SETTINGS_TABLE_SECTION_INTEGERS_ID_HEADER,SETTINGS_TABLE_SECTION_INTEGERS_HEADER));
   model->setRelation(2,QSqlRelation(SETTINGS_TABLE_SECTIONS_COLUMNS,SETTINGS_TABLE_SECTION_COLUMNHEADER_ID_HEADER,SETTINGS_TABLE_SECTION_COLUMNHEADER_HEADER));
   model->setRelation(3,QSqlRelation(SETTINGS_TABLE_NO_OF_SONGS_PER_PAGE_INTEGERS,SETTINGS_TABLE_SECTION_INTEGERS_ID_HEADER,SETTINGS_TABLE_SECTION_INTEGERS_HEADER));

   model->setHeaderData(1,Qt::Horizontal,SETTINGS_TABLE_SECTION_SECTIONS_HEADER);
   model->setHeaderData(2,Qt::Horizontal,SETTINGS_TABLE_SECTION_SORT_HEADER);
   model->setHeaderData(3,Qt::Horizontal,SETTINGS_TABLE_SECTION_SONGS_PER_PAGE_HEADER);

   //I spent ages getting this to work. When I added in the Relations it wouldn't update the database
   //It worked fine without relations. Eventually I checked online and it suggested that one of the database tables columns needed to be a primary key
   // I made the first one a primary key but that didn't work. I eventually added a dummy column and made that a Primary key and that worked

   model->select();

   settingsViewSections->setModel(model);
   settingsViewSections->setColumnHidden(0,true);
   // I had to add a dummy column and call it Primary Key for this table to work so this just hides the column
   settingsViewSections->verticalHeader()->setVisible(false);
   //this gets rid of the Row header

   settingsViewSections->setItemDelegate(new QSqlRelationalDelegate(settingsViewSections));
   //standard delegate provides an editor widget for editing fields in the table
   settingsViewSections->setItemDelegateForColumn(2,new CustomDelegateComboBox(m_columnsToHide, settingsViewSections));
   // My custom delegate to try to grey out items in the settings Columns tab that are not selected in the Columns tab

   QWidget *newTab = new QWidget;
   //set up a frame so that spinbox and combobox are not stretched fully across the window or too far apart vertically
   QFrame *frame = new QFrame(newTab);
   frame->setAutoFillBackground(true);
   frame->setGeometry(0,0,DIALOGWIDTH/WIDTHSCALINGFACTOR,DIALOGHEIGHT/HEIGHTSCALINGFACTOR);

   QVBoxLayout *frameLayout = new QVBoxLayout;
   frameLayout->addWidget(settingsViewSections);
   frame->setLayout(frameLayout);

   return newTab;
}


void SettingsDialogClass::setSectionsModel(QSqlRelationalTableModel *model)
{
   m_modelSections = model;
}

QSqlRelationalTableModel SettingsDialogClass::getSectionsModel()
{
   //return m_modelSections;
}

// Not used
void SettingsDialogClass::dataChangedSlot(const QModelIndex &topLeft, const QModelIndex &bottomRight)
{
   QVariant value = m_modelSections->data(topLeft,Qt::DisplayRole);

   qDebug() << "Slot is running";
   qDebug() << "Top Left" << topLeft;
   qDebug() << "Top Right" << bottomRight;
   qDebug() << "Value" << value;




   m_modelSections->database().transaction();
   if (m_modelSections->submitAll())
   {
       m_modelSections->database().commit();
   }
   else
   {
       m_modelSections->database().rollback();

//        qDebug() << m_modelSections->lastError().text();

       QMessageBox msgBox;
       msgBox.setWindowTitle("Database Error");
       msgBox.setIcon(QMessageBox::Warning);
//        msgBox.setText(tr("The database reported an error: %1")
//                       .arg(m_modelSections->lastError().text()));
       //msgBox.setInformativeText("More Text...!!");
       msgBox.setStandardButtons(QMessageBox::Ok);
       int reply = msgBox.exec();

       if(reply==QMessageBox::Ok)
       {
           return;
       }
       m_modelSections->select();
   }
}


// Pushbuttons slots
void SettingsDialogClass::on_buttonBox_accepted()
{
   //Update model for column Tab table
   m_modelColumns->database().transaction();
   if (m_modelColumns->submitAll())
   {
       m_modelColumns->database().commit();
   }
   else
   {
       m_modelColumns->database().rollback();
       QMessageBox msgBox;
       msgBox.setWindowTitle("Database Error");
       msgBox.setIcon(QMessageBox::Warning);
//        msgBox.setText("Datbase Error: %1").arg(m_model->lastError().text());
       msgBox.setStandardButtons(QMessageBox::Ok);
       msgBox.exec();
   }

   //Update model for Sections Tab table
   m_modelSections->database().transaction();
   if (m_modelSections->submitAll())
   {
       m_modelSections->database().commit();
   }
   else
   {
       m_modelSections->database().rollback();
       QMessageBox msgBox;
       msgBox.setWindowTitle("Database Error");
       msgBox.setIcon(QMessageBox::Warning);
//        msgBox.setText("Datbase Error: %1").arg(m_model->lastError().text());
       msgBox.setStandardButtons(QMessageBox::Ok);
       msgBox.exec();
   }
}

void SettingsDialogClass::on_buttonBox_rejected()
{
   m_modelColumns->database().rollback();
   m_modelSections->database().rollback();
}

##Custom delegate

/****************************************************************************
** 
** 20/11/19
**
** This custom delegate is to restrict the values shown in the settings dialog 'sort by'
** column to only allow selected columns to be chosen (Selected in the Columns tab
**
** It reimplements setEditor data to restrict combobox values based on selected columns in columns tab
**
** Dec 19 - Initially just uses a QMessageBox to say that you are trying to sort by unticked
** value but this doesn't work because it allows you select an incorrect value and then next time
** you try to edit it shows you the message box
** ?? - Ideally I want to have unticked values greyed out so they can't be selected
**
****************************************************************************/



#include <QtWidgets>
#include <QWidget>
#include "customdelegatecombobox.h"
#include "constants.h"
#include "sqlitedb.h"

CustomDelegateComboBox::CustomDelegateComboBox(QStringList columnsToHide, QWidget *parent)
{
    m_columnsToHide = columnsToHide;
}

QWidget *CustomDelegateComboBox::createEditor(QWidget *parent, const QStyleOptionViewItem &option,const QModelIndex &index) const
{
//    QComboBox *editor = new QComboBox(parent);

    QSqlRelationalDelegate::createEditor(parent,option,index);

//    return editor;
}

void CustomDelegateComboBox::setEditorData(QWidget *editor, const QModelIndex &index) const
{
    if (!m_columnsToHide.isEmpty())
    {
        QComboBox *cbox = static_cast<QComboBox *>(editor);
//        QComboBox *cbox = qobject_cast<QComboBox *>(editor);
//        cbox->addItem("Test");


//        QStandardItemModel* model = qobject_cast<QStandardItemModel*>(cbox->model());
//        QStandardItem* item= model->item(0); // *****crashes here!!****
//        item->setFlags(item->flags() & ~Qt::ItemIsEnabled);

        //disable unticked columns
        //?????
        // Tried a few things without success - Moving on and I will get some help and come back

//https://stackoverflow.com/questions/11439773/disable-item-in-qt-combobox/21740341
        //QStandardItemModel *model = dynamic_cast<QStandardItemModel *> (cbox->model());

////https://stackoverflow.com/questions/11439773/disable-item-in-qt-combobox/21740341
//        QListWidget *contents = new QListWidget(cbox);
//        contents->hide();
//        cbox->setModel(contents->model());

//        QStringList list;
//        list << "SID" << "Song" << "Artist" << "Tuning";

//        for (int i=0;i<m_columnsToHide.size();i++)
//        {
//            contents->addItems(list);
//        }

        //const QAbstractItemModel *model = index.model(); //This gives a model woth only 1 row


// this crashes on model->rowcount
//        for (int i=0;i<model->rowCount();i++)
//        {
//            QModelIndex indx = model->index(i,0);
//            QVariant data = model->data(indx,Qt::DisplayRole);
//        }




        //item->setEnabled(false); //DOn't know if this works yet



    }
    else
    {
        QSqlRelationalDelegate::setEditorData(editor, index);
    }

}

void CustomDelegateComboBox::setModelData(QWidget *editor, QAbstractItemModel *model,const QModelIndex &index) const
{
    int flag=0;
    if (!m_columnsToHide.isEmpty())
    {
        //Model value
        QString value = index.model()->data(index, Qt::EditRole).toString();
        qDebug() << value;

        QComboBox *cbox = static_cast<QComboBox *>(editor);
        //Selected value
        value = cbox->currentText();
        qDebug() << value;

        for (int i=0;i<m_columnsToHide.size();i++)
        {
            if (value == m_columnsToHide[i])
            {
                flag = 1;
                break;
            }
        }
        if (flag==1)
        {
            QMessageBox msgBox;
            QString windowTitle = "Column Error - " + QString("%1").arg(value);
            msgBox.setWindowTitle(windowTitle);
            msgBox.setIcon(QMessageBox::Warning);
            msgBox.setText("Column is not selected in Column tab");
            msgBox.setInformativeText("If you need to sort by this column, tick checkbox in column tab");
            msgBox.setStandardButtons(QMessageBox::Ok);
            int reply = msgBox.exec();
        }
        else
        {
            QSqlRelationalDelegate::setModelData(editor,model,index);
        }


    }
    else
    {
        QSqlRelationalDelegate::setModelData(editor,model,index);
    }
}

[Christian Ehrlicher]

@cdontheqt said in How to grey out items in a QTableview delegate editor:

but the program crashes

Use a debugger and see where it crashes and fix your code.

[VRonin]

@cdontheqt said in How to grey out items in a QTableview delegate editor:

I have used a standard delegate on the tableviews to allow editing.

I think it's much easier to do with a proxy model instead

class GreyUncheckedProxy : public QIdentityProxyModel{
    Q_OBJECT
    Q_DISABLE_COPY(GreyUncheckedProxy)
public:
    using QIdentityProxyModel::QIdentityProxyModel;
    Qt::ItemFlags flags(const QModelIndex &index) const override{
        if(index.data(Qt::CheckStateRole).toInt() == Qt::Unchecked)
            return Qt::NoItemFlags;
        return QIdentityProxyModel::flags(index);
    }
};