Golang : Read tab delimited file with encoding/csv package



Tags : golang csv tab-delimited convert json

This tutorial is just a slight modification from previous tutorial on how to read CSV file and save the result to JSON format file. In this tutorial, we will learn how to instruct the Golang's CSV reader to recognize the tab character '\t' instead of , comma as separator.

To do that, we need to change the type Reader.Comma (https://golang.org/pkg/encoding/csv/#Reader) default value from ',' to '\t' with this line :

 reader.Comma = '\t' // Use tab-delimited instead of comma

and if you are looking to write out tab delimited file instead of comma, remember to change the default value for type Writer.Comma (https://golang.org/pkg/encoding/csv/#Writer) as well.

Let's see how it goes.

We will process the tabdata.csv file

 Adam 36 CEO
 Eve 34 CFO
 Mike 38 COO

with this code :

 package main

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

 type Employee struct {
 Name string
 Age  int
 Job  string
 }

 func main() {
 // read data from CSV file

 csvFile, err := os.Open("./tabdata.csv")

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

 defer csvFile.Close()

 reader := csv.NewReader(csvFile)

 reader.Comma = '\t' // Use tab-delimited instead of comma <---- here!

 reader.FieldsPerRecord = -1

 csvData, err := reader.ReadAll()
 if err != nil {
 fmt.Println(err)
 os.Exit(1)
 }

 var oneRecord Employee
 var allRecords []Employee

 for _, each := range csvData {
 oneRecord.Name = each[0]
 oneRecord.Age, _ = strconv.Atoi(each[1]) // need to cast integer to string
 oneRecord.Job = each[2]
 allRecords = append(allRecords, oneRecord)
 }

 jsondata, err := json.Marshal(allRecords) // convert to JSON

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

 // sanity check
 // NOTE : You can stream the JSON data to http service as well instead of saving to file
 fmt.Println(string(jsondata))

 // now write to JSON file

 jsonFile, err := os.Create("./data.json")

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

 var oneRecord Employee
 var allRecords []Employee

 for _, each := range csvData {
 oneRecord.Name = each[0]
 oneRecord.Age, _ = strconv.Atoi(each[1]) // need to cast integer to string
 oneRecord.Job = each[2]
 allRecords = append(allRecords, oneRecord)
 }

 jsondata, err := json.Marshal(allRecords) // convert to JSON

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

 // sanity check
 // NOTE : You can stream the JSON data to http service as well instead of saving to file
 fmt.Println(string(jsondata))

 // now write to JSON file

 jsonFile, err := os.Create("./data.json")

 if err != nil {
 fmt.Println(err)
 }
 defer jsonFile.Close()

 jsonFile.Write(jsondata)
 jsonFile.Close()
 }

run the code above and the output will be stored in the data.json file with the following data :

 [{"Name":"Adam","Age":36,"Job":"CEO"},{"Name":"Eve","Age":34,"Job":"CFO"},{"Name":"Mike","Age":38,"Job":"COO"}]

Hope this is useful to you.

References :

https://www.socketloop.com/tutorials/golang-convert-csv-data-to-json-format-and-save-to-file

https://golang.org/pkg/encoding/csv/#Reader

  See also : Convert JSON to CSV in Golang



Tags : golang csv tab-delimited convert json

By Adam Ng

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