You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: service.go
    path of file: ./repos/incubator-devlake/backend/plugins/customize/service
    
    the code of the file until where you have to start completion: /*
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements.  See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License.  You may obtain a copy of the License at

    http:/
    
func (s *Service) GetFields(table string) ([]models.CustomizedField, errors.Error) {
	// the customized fields created before v0.16.0 were not recorded in the table `_tool_customized_field`, we should take care of them
	columns, err := s.dal.GetColumns(&models.Table{Name: table}, func(columnMeta dal.ColumnMeta) bool {
		return true
	})
	if err != nil {
		return nil, errors.Default.Wrap(err, "GetColumns error")
	}
	ff, err := s.getCustomizedFields(table)
	if err != nil {
		return nil, err
	}
	fieldMap := make(map[string]models.CustomizedField)
	for _, f := range ff {
		fieldMap[f.ColumnName] = f
	}
	var result []models.CustomizedField
	for _, col := range columns {
		// original fields
		if !strings.HasPrefix(col.Name(), "x_") {
			dataType, _ := col.ColumnType()
			result = append(result, models.CustomizedField{
				TbName:     table,
				ColumnName: col.Name(),
				DataType:   dal.ColumnType(dataType),
			})
			// customized fields
		} else {
			if field, ok := fieldMap[col.Name()]; ok {
				result = append(result, field)
			} else {
				result = append(result, models.CustomizedField{
					ColumnName: col.Name(),
					DataType:   dal.Varchar,
				})
			}
		}
	}
	return result, nil
}