How to process JSON data in Go language?

In recent years, the JSON (JavaScript Object Notation) data format has become one of the most popular formats in web development. The Go language provides excellent support for processing JSON data. This article will introduce how to process JSON data in the Go language.

1. JSON data format

Before understanding how to process JSON data in Go language, we need to first understand the JSON data format. JSON is a lightweight data exchange format based on JavaScript Object Notation and supports multiple programming languages. The following is an example of JSON data:

{
    "name": "张三",
    "age": 25,
    "hobbies": ["读书", "旅游", "电影"],
    "contact": {
        "telephone": "13512345678",
        "email": "zs@example.com"
    }
}

In this example, we can see that the JSON data is surrounded by curly braces, and its content includes four key-value pairs, namely name, age, hobbies and contact. Among them, the value of the key name is a string, the value of the key age is a number, the value of the key hobbies is an array, the array contains three strings, and the value of the key contact is a nested JSON data. The nested The data contains two key-value pairs, namely telephone and email.

2. JSON processing in Go language

In Go language, we can process JSON data through the encoding/json package. This package provides two functions, Marshal and Unmarshal, which can be used to convert data types in Go language to JSON format or convert JSON format data to Go language data types.

1. Marshal function

The Marshal function is used to convert data types in Go language to JSON format data. The definition of this function is as follows:

func Marshal(v interface{}) ([]byte, error)

This function receives an interface type parameter v, which represents the Go language data type to be converted. This function returns a byte array and an error value. If the conversion is successful, the error value is nil, otherwise the corresponding error message will be returned.

The following is an example of using the Marshal function to convert the structure type in the Go language into data in JSON format:

package main

import (
    "encoding/json"
    "fmt"
)

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

func main() {
    p := Person{Name: "张三", Age: 25}
    b, err := json.Marshal(p)
    if err != nil {
        fmt.Println("转换失败", err)
        return
    }
    fmt.Println(string(b))
}

In this example, we define a structure named Person Structure type, which contains two fields Name and Age, and uses json:"name" and json:"age" tags on the fields of the structure. These tags Used to specify the key name of the corresponding field when converting to JSON format data.

In the main function, we create an instance p of the Person type, and then use the json.Marshal function to convert the instance into JSON format data. After the conversion is successful, the result is printed to the console.

The output results are as follows:

{"name":"张三","age":25}

You can see that the Person type in the Go language is converted into JSON format data.

2. Unmarshal function

The Unmarshal function is used to convert data in JSON format into data types in the Go language. The definition of this function is as follows:

func Unmarshal(data []byte, v interface{}) error

This function receives two parameters. The first parameter data represents the JSON format data to be converted. It is a byte array. The second parameter v represents the data to be converted into Go language data type, which is an interface type.

The following is an example of using the Unmarshal function to convert JSON format data into a structure type in the Go language:

package main

import (
    "encoding/json"
    "fmt"
)

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

func main() {
    s := `{"name":"张三","age":25}`
    var p Person
    err := json.Unmarshal([]byte(s), &p)
    if err != nil {
        fmt.Println("转换失败", err)
        return
    }
    fmt.Println(p)
}

In this example, we first define a named Person Structure type, then in the main function, we create a JSON format data s, which is consistent with the data in the previous example, and then use the json.Unmarshal function to convert the JSON format data into Go language Person type, after successful conversion, the result will be printed to the console.

The output results are as follows:

{张三 25}

As you can see, the JSON format data is converted into the Person type in the Go language.

To sum up, the Go language provides very convenient support for processing data in JSON format. Using the Marshal and Unmarshal functions in the encoding/json package, you can easily convert data types in Go language to JSON format or convert JSON format data to Go language data types.

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