csv to yaml converter

csv2yaml.go

package main

import (
	"encoding/csv"
	"io"
	"os"
	"sort"

	"gopkg.in/yaml.v2"
)

type sortByKey yaml.MapSlice

func (p sortByKey) Len() int {
	return len(p)
}

func (p sortByKey) Less(i, j int) bool {
	keyA := p[i].Key.(string)
	keyB := p[j].Key.(string)
	if keyA == keyB {
		return false
	}
	if keyA == "id" {
		return true
	}
	if keyB == "id" {
		return false
	}
	return keyA < keyB
}

func (p sortByKey) Swap(i, j int) {
	p[i], p[j] = p[j], p[i]
}

func main() {
	var input io.Reader
	var err error
	if len(os.Args) >= 2 {
		input, err = os.Open(os.Args[1])
		if err != nil {
			panic(err)
		}
	} else {
		input = os.Stdin
	}

	reader := csv.NewReader(input)
	header, err := reader.Read()
	if err != nil {
		panic(err)
	}

	data := []yaml.MapSlice{}
	for {
		row, err := reader.Read()
		if err == io.EOF {
			break
		} else if err != nil {
			panic(err)
		}

		rowdata := make(yaml.MapSlice, 0, len(header))
		for i, name := range header {
			if i < len(row) {
				rowdata = append(rowdata, yaml.MapItem{
					Key:   name,
					Value: row[i],
				})
			}
		}

		sort.Stable(sortByKey(rowdata))
		data = append(data, rowdata)
	}

	out, err := yaml.Marshal(data)
	if err != nil {
		panic(err)
	}

	_, err = os.Stdout.Write(out)
	if err != nil {
		panic(err)
	}
}