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Go for Data Processing: Working with CSV and JSON Files

Go for Data Processing: Working with CSV and JSON Files

The Go language is known for its simplicity, efficiency, and powerful standard library, making it a great choice for data processing tasks. This article will provide a comprehensive guide to working with CSV and JSON files in Go.

Prerequisites

  • Go installed (version 1.16 or later)
  • Basic knowledge of Go programming language

Table of Contents:

Processing CSV Files in Go

Reading CSV Files

Let’s start by reading a CSV file. Go has an in-built encoding/csv package for dealing with CSV data.

Create a new file read_csv.go and add the following code:

package main

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

func main() {
	f, err := os.Open("data.csv")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	r := csv.NewReader(f)

	records, err := r.ReadAll()
	if err != nil {
		log.Fatal(err)
	}

	for _, record := range records {
		fmt.Println(record)
	}
}

This code opens a file named data.csv, reads it as a CSV file, and prints each record (row).

Writing CSV Files

Similarly, we can write CSV data with the encoding/csv package. The following code writes some data to a CSV file:

package main

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

func main() {
	f, err := os.Create("output.csv")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	w := csv.NewWriter(f)
	defer w.Flush()

	data := [][]string{
		{"Name", "Age", "City"},
		{"Alice", "23", "New York"},
		{"Bob", "27", "San Francisco"},
	}

	for _, record := range data {
		if err := w.Write(record); err != nil {
			log.Fatal(err)
		}
	}
}

This code writes the data array to a file named output.csv.

Processing JSON Files in Go

Reading JSON Files

Go has an in-built encoding/json package for dealing with JSON data. The following code reads a JSON file:

package main

import (
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"os"
)

type Person struct {
	Name string `json:"name"`
	Age  int    `json:"age"`
	City string `json:"city"`
}

func main() {
	f, err := os.Open("data.json")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	bytes, err := ioutil.ReadAll(f)
	if err != nil {
		log.Fatal(err)
	}

	var people []Person
	if err := json.Unmarshal(bytes, &people); err != nil {
		log.Fatal(err)
	}

	fmt.Println(people)
}

This code opens a file named data.json, reads it as a JSON file, and prints each object.

Writing JSON Files

We can also write JSON data with the encoding/json package. Here is how to write some data to a JSON file:

package main

import (
	"encoding/json"
	"log"
	"os"
)

type Person struct {
	Name string `json:"name"`
	Age  int    `json:"age"`
	City string `json:"city"`
}

func main() {
	f, err := os.Create("output.json")
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()

	people := []Person{
		{Name: "Alice", Age: 23, City: "New York"},
		{Name: "Bob", Age: 27, City: "San Francisco"},
	}

	bytes, err := json.Marshal(people)
	if err != nil {
		log.Fatal(err)
	}

	if _, err := f.Write(bytes); err != nil {
		log.Fatal(err)
	}
}

This code writes the people slice to a file named output.json.

Conclusion

In this article, we explored how to use Go to read and write CSV and JSON files. With its powerful standard library, Go makes these common data processing tasks simple and efficient. Whether you’re dealing with small data files or large datasets, Go is an excellent tool for your data processing needs.

faizan

Faizan Bashir

Principal Engineer | Architecting and building distributed applications in the Cloud | Adventurer

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