How to get a record to insertRecord(-1, rec) in QSqlRelationalTableModel

[SwissKnife]

What is the best way to get a record to insert a new row to the base table with foreign keys?

When using record() or QSqlTableModel::record() after setRelation(...), the returned record contains fields with the column names of the display column.
A inserRecord( -1, row ) with these fields fails, because the fields are not present in the table?

I would expect that QSqlTableModel::record() returns a useful record, or that a record with display columns is transformed back to foreign key columns?

My solution is to store a copy of original record before setting the relations.
Is there a more generic solution?

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SqlAttachmentModel::SqlAttachmentModel( QSqlDatabase db, QObject *parent)
: QSqlRelationalTableModel(parent, db)
{
setTable( "Attachment" );

// store record to use as template for insertRecord()
mBaseTableRecord = record();

setRelation( eAnimalId, QSqlRelation( "animal", "uId", "earTag"));
setRelation( eUnitId, QSqlRelation( "rumiWatchUnit", "uId", "serialNumber"));

// get useless record with display columns fields
mRelationalRecord = QSqlTableModel::record();

}
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