code: func (tl TypeLoader) LoadIndexColumns(args *ArgType, ixTpl *Index) error {
  	var err error
  
  	// load index columns
  	indexCols, err := tl.IndexColumnList(args.DB, args.Schema, ixTpl.Type.Table.TableName, ixTpl.Index.IndexName)
  	if err != nil {
  		return err
  	}
  
  	// process index columns
  	for _, ic := range indexCols {
  		var field *Field
  
  	fieldLoop:
  		// find field
  		for _, f := range ixTpl.Type.Fields {
  			if f.Col.ColumnName == ic.ColumnName {
  				field = f
  				break fieldLoop
  			}
  		}
  
  		if field == nil {
  			continue
  		}
  
  		ixTpl.Fields = append(ixTpl.Fields, field)
  	}
  
  	return nil
  }
docs: // LoadIndexColumns loads the index column information.