How to read JSON data from file using ioutil in Golang?

To use ioutil to read JSON data from a file in Go, follow these steps: Use ioutil.ReadFile() to read the file contents. Use json.Unmarshal() to decode the byte array into a JSON object. Access the decoded data.

#How to use ioutil to read JSON data from a file in Go?

The Go language provides the ioutil package for reading and writing files. To read JSON data from a file, you can use the ioutil.ReadFile() function. This function returns a byte array containing the entire contents of the file. We can then use the json.Unmarshal() function to decode the byte array into a JSON object.

Code example:

package main

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

type Data struct {
    Name string
    Age  int
}

func main() {
    // 读取文件内容
    bytes, err := ioutil.ReadFile("data.json")
    if err != nil {
        fmt.Println(err)
        return
    }

    // 将字节数组解码为 JSON 对象
    var data Data
    if err := json.Unmarshal(bytes, &data); err != nil {
        fmt.Println(err)
        return
    }

    // 访问解码后的数据
    fmt.Println(data.Name) // 输出: John
    fmt.Println(data.Age)  // 输出: 30
}

Practical case:

Suppose we have a file named data.json file containing the following JSON data:

{
  "Name": "John",
  "Age": 30
}

We can use the code in the code sample to read and decode this data and then obtain the Name## of the Data object # and Age fields.

Output:

John
30

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