@VRonin That's really useful, thank you very much. Also I didn't know about the "Model test", that's nice too.

I'll update this post once I go anywhere with it

This feedback sounds promising.

I am becoming more curious around another description for a similar use case:
An associative table can be created. QStandardItem objects can be generated then based on table entries. Which ways would you like to recommend for the connection of entities to their relationship data?

@MrBolton
Thanks for replying.

Your solution is not what I am looking for, unfortunately. I do not even have a QSortFilterProxyModel. Specifically, I do not want sorting to happen at the client. I wish it to happen at the server with a ORDER BY. My problem, IIRC, is that

QTableView::setSortingEnabled(true); QTableView::sortByColumn(col, Qt.DescendingOrder);

causes two SQL queries to be sent to the database, one for each line. Reversing the order of the two lines does not help. According to me, it is therefore not possible to enable sorting and pick which column to sort by without executing two queries in a row, which is ridiculously wasteful since we only care about the result of the second query. Users may not even be aware that this is what is happening behind the scenes. There should surely be some way of enabling sorting and specifying the column+direction without issuing two separate queries to the database. Nobody else but me seems to think this is an issue/bad/wrong!

I realise this question is now OT. If you would care to share your help on this matter please be kind enough to post in my original thread, https://forum.qt.io/topic/83294/how-to-prevent-qtableview-qtreeview-doing-query-sorting-multiple-times. Thank you.

What's the problem replacing the QSpinBox with a QComboBox in the example? Did you even try?

Do you mean custom graphicsView or tableView? If custom graphics view wouldn't it be too hard to reimplement everything? Any links or example would help.

@JonB This adds a new, blank row at the end of the table model. But you do not set that row to hold your component / text?
How to do it? I did not correctly understand what this function does, so if it's not hard for you. You can suggest how to insert text in the first free cell

@Arthur-Araruna said in Replicate the contents of the current selected item in QTableView:

both column and row indices

All you need to do is replace currentRowChanged with currentIndexChanged

I created custom model which works fast enough. It fetches and writes data using queries. Seems like working solution.

@mmikeinsantarosa
Hi
just to be clear
You do not name the parameter when using a function in a connect.
Nor for signal OR the slot.

So if you function is like
void MySlot( int ID, QString Name) ( in .h and cpp)

you would only use as
MySlot( int, QString) for connect.

Hi
it will only be a problem if you make too long lasting loop.
Then it will stop redrawing.

Hi,

http://doc.qt.io/qt-5/designer-using-custom-widgets.html You don't need to, just call setModel like you are doing currently Do you mean something like: MyView *view = new MyView; ui->layout_name->add(view);

?

@VRonin I got it corrected!
searchProxy->setSourceModel(modal);
ui->tableView->setModel(searchProxy);

should be put inside the search button method!

The answer in stackoverflow is correct.

Is there no other way to get notified when an Edit begins?

just declare and emit your custom signal in the delegate subclass

Remember 1 model can service multiple views so, normally, the model should not depend on the state of the view or delegate

@Kushan
Or you can use resizeColumnsToContents() method for the same.

You can use either QTreeWidget, QTableWidget, QTreeView+QStandardItemModel, QTableView+QStandardItemModel, QTreeView+QAbstactTableModel subclass, QTableView+QAbstactTableModel subclass for what you are trying to do.

I would go with a QT*View+QStandardItemModel (tree or table doesn't matter).

The functionalities you describe are:

only some columns will be editable

use QStandardItem::setFlag

Entering a value in the cents column (a logarithmic measure of frequency) will change the value in the hertz column, and vice versa

connect a slot to QStandardItemModel::dataChanged signal

There will be a button next to the table to add an additional note to the scale

connect a slot that calls QStandardItemModel::insertRows to the QPushButton::clicked signal

Так проверьте соединение при запуске.

И может, драйвер для SQLite собран только дебаговый? Надо и релизный тоже собрать.

@MrBolton
Sorry, I really don't understand your comment. Precisely the point is that with "bigger data sets" you would have to fetch all the data, which is incredibly slow and may well exceed available memory. (OTOH, if the dataset is "small" the overhead of re-query compared to holding all the previous rows locally is also "small".) As a rule of thumb, one always wants as much work to be done at the server side as possible, not client side.

Let's say the table has a million rows and the query I want to pose is:

SELECT * FROM table ORDER BY column LIMIT 100

Very approximately, pushing the ORDER BY to the server instead of into a QSortFilterProxyModel will run 10 thousand times faster and use one ten-thousandth of the client memory. That's why I would be very careful before advising people to use QSortFilterProxyModel without understanding the ramifications!

Thanks everyone for answer.
I am end up with write my own models, the load time reduce to 3s for 30k row and 150 col each.

Put a QSortFilterProxy model in-between. then save from the proxy instead of the main model.

P.S.
connect(currentTableHeader, SIGNAL(sectionClicked(int)), this, SLOT(on_sectionClicked(int))); and void mainWidget::on_sectionClicked(int index) are useless. this is the default behaviour of QTableView, you don't have to implement it manually

Did you already checked the bug report system to see if there was something related ?

If not, please consider opening a new report providing a minimal compilable example showing the behaviour.

I may be wrong but you can use signal and slot (on changing textbox's text example):

//mainwindow.cpp constructor: MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { // connection for accessing to UI from another UI ProfileSearch* profilesearch = new ProfileSearch; connect( profilesearch, SIGNAL(updateUI1Signal(const QString)), this, SLOT(updateUI2TextSlot(const QString) ) ); // launch profilesearch form: profilesearch.exec(); } //mainwindow.h { public slots: void updateUI2TextSlot( const QString text ) {ui->MWtextEdit->setText(text);} // set new text in mainwindow form } //profilesearch.h signals: void updateUI1Signal(const QString text);

// row click event handler

void ProfileSearch::on_row_column_whatewer_clicked() { emit updateUI1Signal("Hello from ProfileSearch form to MainWindow form"); }

In 90% of the cases you can use QStandardItemModel instead of going through the minefield that is subclassing an abstract model.

My advice is just to use that "universal model" instead of a custom one. If you really, really want to customise it as performance of QStandardItemModel is a problem then make sure you run your model through the Model Test (needs just a couple of trivial fixes to work on Qt5) that will tell you if you did everything as you were supposed to or you fell in the countless pitfalls of model subclassing

Hi and welcome to devnet,

You can use a proxy model that adds the columns you want/need.

You can keep updating the DB content and trigger the GUI update at some known interval or when a certains amount of changed happened to the database.

@blastdoman You are correct, let's try this:

#include <QStyledItemDelegate> class DataChangeDelegate : public QStyledItemDelegate{ Q_OBJECT Q_DISABLE_COPY(DataChangeDelegate) public: enum{IsDirtyRole=Qt::UserRole + 44}; explicit DataChangeDelegate(QObject* parent=Q_NULLPTR) :QStyledItemDelegate(parent) {} virtual void setModelData(QWidget *editor, QAbstractItemModel *model, const QModelIndex &index) const Q_DECL_OVERRIDE{ const QVariant oldData = index.data(Qt::EditRole); QStyledItemDelegate::setModelData(editor,model,index); if(index.data(Qt::EditRole)!=oldData) model->setData(index,true,IsDirtyRole); } }; DataChangeDelegate* signalingDelegate=new DataChangeDelegate(this); connect(tableView->selectionModel(),&QItemSelectionModel::currentChanged,this,[this](const QModelIndex& idx)->void{ const int newRow= idx.isValid() ? idx.row():-1; if(newRow==currentRow) return; if(currentRow>=0){ const int maxCols =idx.model()->columnCount(idx.parent()); for(int i=0;i<maxCols ;++i){ if(idx.model()->index(currentRow,i,idx.parent()).data(DataChangeDelegate::IsDirtyRole).toBool()){ validateRow(currentRow); /* inside validateRow call something like: for(int i=0;i<model->columnCount();++i) model->setData(model->index(currentRow,i),QVariant(),DataChangeDelegate::IsDirtyRole); */ break; } } } currentRow=newRow; }); tableView->setItemDelegate(signalingDelegate);

this should return the list of the row indexes as sorted in the view. Hidden rows will be placed at the beginning

QList<int> viewIndexes(const QHeaderView* const view){ if(!view) return QList<int>(); const int numSections= view->count(); QMap<int,int> sorter; for(int i=0;i<numSections;++i) sorter.insert(view->sectionPosition(i),i); return sorter.values(); }

or alternatively:

QVector<int> viewIndexes(const QHeaderView* const view){ if(!view) return QVector<int>(); const int numSections=view->count(); QVector<int> result(numSections); for(int i=0;i<numSections;++i) result[i]=i; // Use stable_sort if you want the hidden sections still placed at the beginning but in the same order as the original model std::sort(result.begin(),result.end(),[view](int a,int b)->bool{return view->sectionPosition(a)<view->sectionPosition(b);}); return result; }

You'll have to benchmark them to tell which is more efficient

I've uncovered the same issue with QSqlQueryModel using the Windows QODBC database engine connected to MS SQL Server, and have been do some digging. Hopefully this will help others experiencing this issue.

There are a couple of different things happening here.

First, QSqlQueryModel does not support forward only queries. If you try to use a forward only query, QSqlQueryModel::lastError() will return "Forward-only queries cannot be used in a data model".

That seems clear, but does not explain the situation when the forward only is left in its default false state or explicitly set in code. During my exploration of the issue, I would notice that even though I called QSqlQuery::setForwardOnly(false), a call to QSqlQuery::isForwardOnly() made after the query was executed would show forward only set to true, something I did not understand.

Then I read the Qt documentation for setForwardOnly:

Setting forward only to false is a suggestion to the database engine, which has the final say on whether a result set is forward only or scrollable. isForwardOnly() will always return the correct status of the result set.

The database engine has the final say whether or not forward only is used!

Why was the database engine setting forward only? Qt's SQL Database Drivers documentation gives part of the answer if you know what you are looking at.

ODBC Stored Procedure Support

With Microsoft SQL Server the result set returned by a stored procedure that uses the return statement, or returns multiple result sets, will be accessible only if you set the query's forward only mode to forward using QSqlQuery::setForwardOnly().

By observation, the QODBC database engine (in Qt 5.8) recognizes when more than one return set has resulted from the query, so it is automatically setting forward only to true.

How are multiple result sets generated? I've uncovered a few ways.

A query that has multiple select statements (e.g. select * from table1; select * from table2). Stored Procedures In particular, MS SQL Server documentation has this to say:

SQL Server stored procedures have four mechanisms used to return data:

Each SELECT statement in the procedure generates a result set. The procedure can return data through output parameters. A cursor output parameter can pass back a Transact-SQL server cursor. The procedure can have an integer return code.

The first item in Microsoft's list was the key for me. When NOCOUNT is OFF, Even a simple internal variable assignment using a select (e.g. select @user = 'fred') generated a return set. Setting NOCOUNT to ON stops this behavior. From Microsoft's documentation on NOCOUNT

SET NOCOUNT ON prevents the sending of DONE_IN_PROC messages to the client for each statement in a stored procedure. For stored procedures that contain several statements that do not return much actual data, or for procedures that contain Transact-SQL loops, setting SET NOCOUNT to ON can provide a significant performance boost, because network traffic is greatly reduced.

The Solution for me turned out to be two things:

Add SET NOCOUNT ON to the top of my stored procedure so that only the select statement I cared about was returned Instead of using QSqlQueryModel, manually extract the results from the query and build my own QStandardItemModel.

@VRonin hey it works. I created a separate qt project and it's working there. I will see if I am doing something wrong in my project.

Actually the row to which I am trying to set a background color also has some color set to it in table widget stylesheet. Also tablewidget items also have a background color. I will check there. Thanks again.

Glad you found a solution !

Can you share a small sample code that triggers this behaviour ?

@IMAN4K said in change QSortFilterProxyModel behaviour for multiple column filtering:

Answer from stackfverflow : http://stackoverflow.com/questions/39488901/change-qsortfilterproxymodel-behaviour-for-multiple-column-filtering

This answer is the typical example that lead people to say

subclassing QSortFilterProxyModel, which would likely have a very limited reusability

It's bad. the proxy model implementation should not depend on the structure of the underlying data in sourceModel

@raven-worx: while I'm not sure it is the right solution for what @tokafr wants to do, he can take ownership of the vertical scrollbar and have some influence this way. I have done it before that way.

@tokafr: Instead of trying to influence the hidden layout of the QTableView, you could mask the space between the header view and the vertical scrollbar to make it look like it being part of the header view. Stylesheets are probably the best place to try.

Hi
Did you have a look at
http://doc.qt.io/qt-4.8/qitemeditorfactory.html#details

Seems to be such editor cache, like you have/want.

Hi again Vronin;

I improve little bit your idea. Perphaps is usefull for somebody.
As I comment before, my tableview will have diferent types of Aligment. Some columns goes to right, other left, other center.
But, I will use the same subclass created for QSqlQueryModel I will call this subclass many times in diferent part of my application.
I created something more variable, so at the moment that you call the subclass you must define by QStringList define in my subclass, for each column what kind of aligment you like.

Thanks Vronin for your help. And I share the code with you

================== MyQSqlQueryModel.h ======================
#ifndef MYQSQLQUERYMODEL_H
#define MYQSQLQUERYMODEL_H
#include <QSqlQueryModel>

#include <QObject>

class MyQSqlQueryModel : public QSqlQueryModel
{
public:
MyQSqlQueryModel();
QVariant data(const QModelIndex &item, int role) const;
QStringList AligmentDefinition; // HERE I DEFINE THE ALIGMENT BY COLUMNS
};

#endif // MYQSQLQUERYMODEL_H

================== MyQSqlQueryModel.cpp ======================
#include "myqsqlquerymodel.h"

MyQSqlQueryModel::MyQSqlQueryModel()
{

}

QVariant MyQSqlQueryModel::data(const QModelIndex &item, int role) const
{
if(role==Qt::TextAlignmentRole)
{
if(AligmentDefinition.size()==0)
{// There are any definition
return 0;
}
if(item.column() > AligmentDefinition.size())
{// There are no definition for that Column
return 0;
}
int i = item.column();
QString Value = AligmentDefinition.value(i);
if(Value =="1")
return int(Qt::AlignRight | Qt::AlignVCenter);
if(Value=="2")
return int(Qt::AlignCenter | Qt::AlignVCenter);
if(Value=="3")
return int(Qt::AlignLeft | Qt::AlignVCenter);
}
return QSqlQueryModel::data(item,role);
}

=============== MAIN PROGRAM =======================
MyQSqlQueryModel *model = new MyQSqlQueryModel;
model->setQuery("SELECT * FROM SPSSourceLines");
model->AligmentDefinition << "1" << "2" << "3";
QModelIndex index;
index = model->index(0,0);
model->data(index,7);

After much experimentation and some luck I found the solution to this mystery.

On startup I had

ui->tvRMA->horizontalHeader()->restoreState(...);

which restored invalid information from previous sessions with different layouts. Clearing the database of previous sessions brought back the proper behaviour.

Mike

@Nosba said:

but how can I know when the user is editing a cell?

I don't know, and that wasn't your original question. One thing you could try is to subclass the view and reimplement the edit() method from where you can emit a signal that notifies you when editing has started. I hope that helps.

Kind regards.

@raven-worx
Jackpot! Thank you so much for your help!! Finally I did it using QFileSystemWatcher.
Thumbs up for you (if possible?!). :)

Thread marked as solved.
Cheers

Sure. Thanks .