Unmarshal/Load CSV record into struct in Go



Tags : golang csv struct

This is just a slight variation to the previous go read csv file tutorial. In this tutorial, we will use our own data structure and try to unmarshal(load) the csv data into the data structure.

1st November 2014 : UPDATED codes to correct earlier mistake as pointed out by Christian von Kietzell below

csv2struct.go

 package main

 import (
 "encoding/csv"
 "fmt"
 "os"
 )

 type TestRecord struct {
 Email string
 Date  string
 }

 func main() {

 csvfile, err := os.Open("somecsvfile.csv")

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 defer csvfile.Close()

 reader := csv.NewReader(csvfile)

 reader.FieldsPerRecord = -1

 rawCSVdata, err := reader.ReadAll()

 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 // sanity check, display to standard output
 for _, each := range rawCSVdata {
 fmt.Printf("email : %s and timestamp : %s\n", each[0], each[1])
 }

 // now, safe to move raw CSV data to struct

 var oneRecord TestRecord

 var allRecords []TestRecord

 for _, each := range rawCSVdata {
 oneRecord.Email = each[0]
 oneRecord.Date = each[1]
 allRecords = append(allRecords, oneRecord)
 }

 // second sanity check, dump out allRecords and see if 
 // individual record can be accessible
 fmt.Println(allRecords)
 fmt.Println(allRecords[2].Email)
 fmt.Println(allRecords[2].Date)


 }

The CSV file contains the following data

more somecsvfile.csv

"jenniferlcl@*****.com","2012-07-03 18:38:06"

"norazlinjumali@*****.com","2010-06-26 19:46:08"

"wilfred5571@*****.com","2010-07-02 21:49:55"

"nas_kas81@*****.com","2010-07-06 12:49:31"

"tammyu3622@*****.com","2010-07-06 13:55:21"

"wakrie@*****.com","2012-03-02 11:00:59"

"yst.shirin@*****.com","2010-07-07 10:19:11"

"annl_107@*****.com","2010-07-07 20:55:59"

"jen_5831@*****.com","2010-07-07 21:12:27"

"hsheyli@*****.com","2011-09-07 00:39:11"

and executing go run csv2struct.go will produce the following output :

email : jenniferlcl@*****.com and timestamp : 2012-07-03 18:38:06

email : norazlinjumali@*****.com and timestamp : 2010-06-26 19:46:08

email : wilfred5571@*****.com and timestamp : 2010-07-02 21:49:55

email : nas_kas81@*****.com and timestamp : 2010-07-06 12:49:31

email : tammyu3622@*****.com and timestamp : 2010-07-06 13:55:21

email : wakrie@*****.com and timestamp : 2012-03-02 11:00:59

email : yst.shirin@*****.com and timestamp : 2010-07-07 10:19:11

email : annl_107@*****.com and timestamp : 2010-07-07 20:55:59

email : jen_5831@*****.com and timestamp : 2010-07-07 21:12:27

email : hsheyli@*****.com and timestamp : 2011-09-07 00:39:11

[{jenniferlcl@*****.com 2012-07-03 18:38:06} {norazlinjumali@*****.com 2010-06-26 19:46:08} {wilfred5571@*****.com 2010-07-02 21:49:55} {naskas81@*****.com 2010-07-06 12:49:31} {tammyu3622@*****.com 2010-07-06 13:55:21} {wakrie@*****.com 2012-03-02 11:00:59} {yst.shirin@*****.com 2010-07-07 10:19:11} {annl107@*****.com 2010-07-07 20:55:59} {jen_5831@*****.com 2010-07-07 21:12:27} {hsheyli@*****.com 2011-09-07 00:39:11}]

wilfred5571@*****.com

2010-07-02 21:49:55

Hope this tutorial is helpful to you on learning how to unmarshal data from file to data structure in Go.

  See also : Golang : How to read CSV file



Tags : golang csv struct

By Adam Ng

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