QSqlRelationalTableModel is messing things up after setting relation

Hi all.

First review the code that I'm using to create the tables.

Code:

void CreateTablesInSQLServer()
{
	QSqlQuery createGroupsTbl("CREATE TABLE grupa_tbl("
		"Grupa_Id int PRIMARY KEY IDENTITY(1,1) NOT NULL,"
		"GrupaName varchar(30) NOT NULL UNIQUE);");
 
 
	QSqlQuery createContactsTbl("CREATE TABLE contacts_tbl("
		"contact_id int PRIMARY KEY IDENTITY(1,1) NOT NULL,"
		"FirstName varchar(30) NULL,"
		"LastName varchar(40) NULL,"
		"Mobile varchar(40) NULL,"
		"Phone varchar(40) NULL,"		
		"GrupaId int NOT NULL,"		
		"FOREIGN KEY (GrupaId) REFERENCES grupa_tbl);");	
}

After that I'm creating the model and populate the model with data.

Code:

QSqlRelationalTableModel *model = new QSqlRelationalTableModel;             //1
model->setTable("contacts_tbl");                                            //2
int i = model->fieldIndex("GrupaId");	                                    //3
model->setRelation(i, QSqlRelation("grupa_tbl", "Grupa_Id", "GrupaName"));  //4
QString TableName = model->tableName();                                     //5
model->select();                                                            //6
int k = model->fieldIndex("GrupaId");                                       //7
int y = model->fieldIndex("LastName");		                            //8
model->setTable("contacts_tbl");                                            //9
int h = model->fieldIndex("GrupaId");     //10

This is the problem:
In line3 i can retrieve the field index for "GrupaId".
After i make the relation in line4 and i populate the model in line6, i cannot retrieve the field index for "GrupaId"(which is FOREIGN KEY) in line8. But i can get the field index for "LastName" and all of the rest columns.

If i call setTable in line9 i can retrieve the field index for "GrupaId", but as a result the relation in line4 is broken and i have to recreate it.

My goal is to retrieve the field index for "GrupaId" without calling

Code:

model->setTable("contacts_tbl");

again and again.

Thanks in advance.