qt - QTableview: display data in specific column based on value in other column -

i have sqlite table containing (among other things) "position" , "state" field.

i want display table in qtableview position header column , state in right column :

id | 1 | 2 | 3 1  | |   |   2  |   |   | e 

which represents following database entries :

id | position | state 1  | 1        | 2  | 3        | e 

what best way ?

thank !

edit : not sure if changes need qtableview editable (by overriding setdata method of qsqlquerymodel)

the simplest option case create class inherits qsqltablemodel , modify necessary functions shown below:

sqltablemodel.h

#ifndef sqltablemodel_h #define sqltablemodel_h  #include <qsqltablemodel>  class sqltablemodel : public qsqltablemodel {     const qstring statename = "state";     const qstring positionname = "position";  public:     int columncount(const qmodelindex &parent = qmodelindex()) const;     void settable(const qstring &tablename);     qvariant data(const qmodelindex &index, int role = qt::displayrole) const;     qvariant headerdata(int section, qt::orientation orientation, int role = qt::displayrole) const;     qt::itemflags flags(const qmodelindex &index) const;     bool setdata(const qmodelindex &index, const qvariant &value, int role = qt::editrole); private:     int max_position;      int index_position;     int index_state;      void reset(); };  #endif // sqltablemodel_h 

sqltablemodel.cpp

#include "sqltablemodel.h"  #include <qbrush> #include <qsqlquery> #include <qsqltablemodel> #include <qsqlrecord> #include <qtimer>   int sqltablemodel::columncount(const qmodelindex &parent) const {     return qsqltablemodel::columncount(parent)+ max_position;; }  void sqltablemodel::settable(const qstring &tablename) {      qsqltablemodel::settable(tablename);      index_position = fieldindex(positionname);     index_state = fieldindex(statename);      reset(); }  qvariant sqltablemodel::data(const qmodelindex &index, int role) const {     if(role == qt::foregroundrole){         return qbrush(qt::black);     }     const int number_of_columns = qsqltablemodel::columncount();     if(index.column()>= number_of_columns){         if(role==qt::displayrole){             int position = qsqltablemodel::data(this->index(index.row(), index_position), qt::displayrole).toint();             if(index.column() == number_of_columns + position - 1){                 return qsqltablemodel::data(this->index(index.row(), index_state), qt::displayrole).tostring();             }         }     }     return qsqltablemodel::data(index, role); }  qvariant sqltablemodel::headerdata(int section, qt::orientation orientation, int role) const {     if(orientation == qt::horizontal && role == qt::displayrole && section >= qsqltablemodel::columncount())         return section -  qsqltablemodel::columncount() + 1;     return qsqltablemodel::headerdata(section, orientation, role); }  qt::itemflags sqltablemodel::flags(const qmodelindex &index) const {     if(index.column() >= qsqltablemodel::columncount()){         return qt::itemisselectable| qt::itemiseditable| qt::itemisenabled;     }     return qsqltablemodel::flags(index); }  bool sqltablemodel::setdata(const qmodelindex &index, const qvariant &value, int role) {     if(role==qt::editrole){         const int number_of_columns =  qsqltablemodel::columncount();         if(index.column() >= number_of_columns){             bool result1 = qsqltablemodel::setdata(this->index(index.row(), index_position), index.column()-number_of_columns +1, role);             bool result2 = qsqltablemodel::setdata(this->index(index.row(), index_state), value, role);              return result1 && result2;         }         if(index.column() == index_position){             qtimer::singleshot(0, this, &sqltablemodel::reset);         }     }      return qsqltablemodel::setdata(index, value, role); }  void sqltablemodel::reset() {     qsqlquery q;     q.exec(qstring("select max(%1) %2").arg(positionname).arg(tablename()));     int val;     while (q.next()) {         val = q.value(0).toint();     }      if(val != max_position){         beginresetmodel();         max_position = val;         endresetmodel();     } } 

input:

id |position |state 1  |1        |a 2  |2        |s 3  |1        |c 4  |4        |b 5  |3        |v 

output:

the complete example can found in following link