code: func (e *RegisteredEntity) ColumnNames(fieldNames []string) ([]string, error) {
  	if fieldNames == nil || len(fieldNames) == 0 {
  		for _, field := range e.table.ColToField {
  			fieldNames = append(fieldNames, field)
  		}
  	}
  	columnNames := make([]string, len(fieldNames))
  	for i, fieldName := range fieldNames {
  		columnName, ok := e.table.FieldToCol[fieldName]
  		if !ok {
  			return nil, errors.Errorf("%s is not a valid field for %s", fieldName, e.table.StructName)
  		}
  		columnNames[i] = columnName
  	}
  	return columnNames, nil
  }
docs: // ColumnNames translates field names to column names.