Extend QSqlTableModel & Update model data;

[ginkgoguy]

@SGaist
Thanks for your help. If I inherit form QSqlTableModel and add an extra column which function I have to overwrite, only data, headerData and setData?
Yes of course, if I call setData with a specific QModelIndex the signal dataChanged knows the index of the updated cell, but my problem is the step before. I receive position updates every second. The update contains an id corresponding the primary key of an database object and an new position. Now I want to update the appropriate row in the model, so I need a mapping from the id to the row. Or it's possible build a model containing the whole object and connect the update signal to the object slot?

[SGaist]

Also columnCount, otherwise your column won't be shown.

AFAIK, you currently have to do that by hand e.g. using a QHash.

[ginkgoguy]

Thanks for your help.
I decide to inherit from QSortFilterProxyModel, extend it to add additional columns and set the sourceModel to QSqlTableModel .

class ExtraColumnProxyModel : public QSortFilterProxyModel
{
  Q_OBJECT
public:
  ExtraColumnProxyModel(QObject* parent = 0);

  Qt::ItemFlags flags(const QModelIndex &index) const;

  QVariant headerData( int section
                     , Qt::Orientation orientation
                     , int role = Qt::DisplayRole
                     ) const;

  QVariant data(const QModelIndex& index, int role = Qt::DisplayRole) const;

  int columnCount(const QModelIndex &parent = QModelIndex()) const;

  QModelIndex index( int row
                   , int column
                   , const QModelIndex& parent = QModelIndex()
                   ) const;

  void appendColumn(QString columnName);

  QHash<int, QByteArray> roleNames() const;

private:
  QHash<int, QByteArray> m_roles;
  QVector<QString> headerDataVector = QVector<QString>();
};

[SGaist]

So it's working like you wanted it ?

[ginkgoguy]

Yes, the model works correctly. Thanks.
If I want to access the data stored in the extraColumns and I the only thing I get is a identifier-string. I have to create a QHash<QString, QModelIndex> (update it on model change) to get the correct index and a QMap<QModelIndex, $Data> to store and access the values. Or is there a cleaner solution?

[SGaist]

Are you moving rows around ?

[ginkgoguy]

If not, is there a simpler solution?
I was thinking of filter and sort functionality.

[SGaist]

You could put that information at the same index using a custom role but it might be slower to get to the right index when searching for it.

[ginkgoguy]

Sounds like what I'm looking. Can you please describe in more detail what is to be done for or post a link to a describtion?

Best regards

[SGaist]

You can all setData from your model and change the last parameter to a custom value e.g. Qt::UserRole + 1. Define that value in your class so you can easily re-use it.

[ginkgoguy]

Sorry, I was looking for an example , but found nothing on the internet. Can you explain to me the usage of it by short example ?

[SGaist]

An example of myModel->setData(myCustomValue, Qt::UserRole + 1); ?