How to Read a JSON File in Golang

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To read a JSON file in Go, you can use the “json.Unmarshal()” function from the “encoding/json” package.

Example

Let’s say we have the “data.json” file that contains the following content:

{
  "name"  : "Krunal Lathiya",
  "age"   : 30,
  "email" : "krunal@example.com"
}

Now, we will read this JSON file and parse its content.

package main

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

// Define a struct to hold the JSON data
type Student struct {
  Name string `json:"name"`
  Age int `json:"age"`
  Email string `json:"email"`
}

func main() {
  // Open the JSON file
  file, err := os.Open("data.json")
  if err != nil {
    log.Fatalf("Error opening file: %v", err)
  }
  defer file.Close()

  // Read the file content
  content, err := ioutil.ReadAll(file)
  if err != nil {
    log.Fatalf("Error reading file: %v", err)
  }

  // Parse the JSON content
  var student Student
  err = json.Unmarshal(content, &student)
  if err != nil {
    log.Fatalf("Error unmarshalling JSON: %v", err)
  }

  // Use the parsed JSON data
  fmt.Printf("Name: %s\nAge: %d\nEmail: %s\n", 
             student.Name, student.Age, student.Email)
}

Output

Name: Krunal Lathiya
Age: 30
Email: krunal@example.com

In the above code, we defined a Student struct to hold the JSON data.

In the next step, we opened the JSON file using the “os.Open()” function and read its content with the “ioutil.ReadAll()” function.

After that, we parsed the JSON content using the “json.Unmarshal()” function.

Finally, we printed the parsed JSON data to the console.