Is it possible to Convert a QSqlQuery Model to a QsqlTableModel

Asimov

Hi SGaist,

I have tried again this time I am using my model which is created in DbManager class. In the header file the class is set up DbManager myDatabase; and modelBox which is my model is created in that class.

connect(myDatabase.modelBox, SIGNAL(dataChanged(const QModelIndex&)),this,SLOT(test()));

I am just getting it to respond, but it isn't

void MainWindow::test(){
    qDebug() << "signal";
}

So the signal does not seem to be working. I am very perplexed.
I have tried to look at the new qt5 format and that is even more confusing. I don't even now where to put the callback on that. Once I have got the old one to work, I might look into the new one again.

On another note I am now using

delete query;

Which should free up the memory on the stack hopefully.

PS. I am getting this error

QObject::connect: No such signal QStandardItemModel::dataChanged(const QModelIndex&)
QObject::connect:  (receiver name: 'MainWindow')

Asimov

Hi,

After making my last post I decided to call connect from my DbManager class like this

void DbManager::boxList(Ui::MainWindow* ui){
    QSqlQuery* query=new QSqlQuery(mydb);
    query->prepare("select `boxID`,`boxName`,`boxLocation` from `boxes`");
    query->exec();

    modelBox= new QStandardItemModel(sqlSize(query), 3);
    int i=0;
    while (query->next())
    {
        modelBox->setData(modelBox->index(i, 0), query->value("boxID"));
        modelBox->setData(modelBox->index(i, 1), query->value("boxName"));
        modelBox->setData(modelBox->index(i, 2), query->value("boxLocation"));
        i++;
    }
    modelBox->setHeaderData(1, Qt::Horizontal, QObject::tr("Box ID / Name"));
    modelBox->setHeaderData(2, Qt::Horizontal, QObject::tr("Box Location"));
    ui->boxTable->setModel(modelBox);
    ui->boxTable->setColumnHidden(0, true);
    delete query;
    QObject::connect(modelBox, SIGNAL(dataChanged(const QModelIndex &, const QModelIndex &)),modelBox,SLOT(updateBoxList(ui,const QModelIndex & , const QModelIndex &)));
}

The good news is that I have now got rid of the signal error, but now I am getting a slot error like this

QObject::connect: No such slot QStandardItemModel::updateBoxList(ui,const QModelIndex & , const QModelIndex &)

In my DbManager class header I have

public slots:
        void updateBoxList(Ui::MainWindow *ui,const QModelIndex & , const QModelIndex &);

SGaist

Then, why do you pass modelBox as the object containing that slot ?

Again, there's no need to allocate query on the heap, use a local stack variable, that's enough.

Asimov

I used modelBox as the container of the slot because originally I used this, but then I got an error by doing this. Then I changed it to modelBox the name of my model. Anyway I changed it back to this, and it still says there is no slot. I am getting a little confused.

modelBox is the name of the model, which holds the data for the table. You said in your last post not to use the QTableView but the name of the model. So I used the name of the model instead of ui->boxTable which was the name of the QTableView.

I don't know how to use a local stack variable.
It has been a couple of years since I have done any C++, and I am trying to get back into it.
Also I have only been using QT for about a week, so I am new at all this, and having to learn fast.

SGaist

From the code you posted, the slot is in DbManager.

Note that you are trying to do something wrong here. It seems you try to pass the ui variable in SLOT which is not possible.

Since it seems that you manage the model directly in DbManager, there's no need to involve your MainWindow class. Once you update modelBox, it will trigger updates in boxTable automatically.

Asimov

Well SGaist you have solved my signal problem. Taking out the ui worked. My signal is now firing and running my update function, thankyou.

The problem is that I have been passing the ui so I can update the ui. You see when I call void DbManager::boxList(Ui::MainWindow* ui) I send in the ui because my class has no access to the ui, so if I don't pass it in, I can't update anything on the window. So I pass the ui from MainWindow to my class DbManager. This is why I was sending the ui to my function in the slot.

If my function needs to update any ui element then it won't be able to because I have not passed it the ui.
Hmm just had an idea, perhaps when I setup my Dbmanager class I can pass the ui in the contructor and then all my functions will have acces to the ui.

I think I solved the local stack problem now. I had to change query-> to query. all through the code. Here is my new code.

void DbManager::boxList(Ui::MainWindow* ui){
    QSqlQuery query;
    query.prepare("select `boxID`,`boxName`,`boxLocation` from `boxes`");
    query.exec();
    modelBox= new QStandardItemModel(sqlSize(query), 3);
    int i=0;
    while (query.next())
    {
        modelBox->setData(modelBox->index(i, 0), query.value("boxID"));
        modelBox->setData(modelBox->index(i, 1), query.value("boxName"));
        modelBox->setData(modelBox->index(i, 2), query.value("boxLocation"));
        i++;
    }
    modelBox->setHeaderData(1, Qt::Horizontal, QObject::tr("Box ID / Name"));
    modelBox->setHeaderData(2, Qt::Horizontal, QObject::tr("Box Location"));
    ui->boxTable->setModel(modelBox);
    ui->boxTable->setColumnHidden(0, true);
    QObject::connect(modelBox, SIGNAL(dataChanged(const QModelIndex &, const QModelIndex &)),this,SLOT(updateBoxList(const QModelIndex & , const QModelIndex &)));
}

SGaist

Then your design is not good. You are creating a tight coupling that doesn't do much good.

DbManager should not need to know MainWindow nor should it car about it. From what I gathered from your code, it should only operate on the model. If you need your MainWindow to do stuff based on actions from DbManager, then you should implement it through signals and slots. Make your DbManager share information as needed and plug your MainWindow on that. Doing so will make your encapsulation cleaner and if you need to change anything in your MainWindow to modify your GUI then you won't have to change anything in your DbManager class.

Asimov

@SGaist

Partly I agree with you, but it could cause me a few problems.
My DbManager class is to do all database related functions.

In my previous post I showed my function boxList which sets up the model from the database and this is in my Dbmanager class, but without the ui, I couldn't run the following line.

ui->boxTable->setModel(modelBox);

I think I could have more ui functions in MainWindow, and limit my use of ui in my DbManager class.
So I agree in principle, but whether I can get it to work is another thing LOL

SGaist

The request the model from your DbManager through a getter and let the MainWindow set it to whatever widget you want for this task. This will again make the DbManager independent from the GUI.

Asimov

I think I understand.
So I can have a function in DbManager like

QStandardItemModel DbManager::getModelBox()
{
     return modelBox;
}

Then in Windows Main I can call it like this

myDatabase.getModelbox()->setModel(modelBox);

I am going to give tihs a go now. Thanks.

PS. After playing with it for a while I realise my code above was wrong. So here is the code that worked, in case anyone is following this thread

QStandardItemModel* DbManager::getmodelBox()
{
     return modelBox;
}

And in MainWindow I can call it like tihs

ui->boxTable->setModel(myDatabase.getmodelBox());

Thanks SGaist I have learnt a lot. Will mark this thread as solved, even though I got a lot of answers, thanks