How to parse the data returned by the API using JSON processing functions in Go language?

How to use the JSON processing function in Go language to parse the data returned by the API?

1. Introduction
Modern web applications often rely on RESTful APIs to obtain data. Many APIs will return data in JSON format, so when writing web applications using Go language, we often need to process JSON data.

In the Go language, JSON data can be processed through the encoding/json package provided by the standard library. This package has powerful features that help us easily parse the data returned by the API.

2. Parse the JSON data returned by the API
Suppose we call an API that returns the following data in JSON format:

{
   "name": "John",
   "age": 25,
   "email": "john@example.com"
}

We can define a structure to represent this The structure of JSON data:

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

Then, we can use the json.Unmarshal() function to parse the JSON data returned by the API:

import (
    "encoding/json"
    "fmt"
)

func main() {
    jsonData := []byte(`{
        "name": "John",
        "age": 25,
        "email": "john@example.com"
    }`)

    var person Person
    err := json.Unmarshal(jsonData, &person)
    if err != nil {
        fmt.Println("解析JSON数据失败:", err)
        return
    }

    fmt.Println("名称:", person.Name)
    fmt.Println("年龄:", person.Age)
    fmt.Println("邮箱:", person.Email)
}

The output result is:

名称: John
年龄: 25
邮箱: john@example.com

3. Processing the JSON array returned by the API
Sometimes, the data returned by the API may be a JSON array. For example, suppose we call an API that returns a list of users, and it returns the following data in JSON format:

[
    {
        "name": "John",
        "age": 25,
        "email": "john@example.com"
    },
    {
        "name": "Alice",
        "age": 28,
        "email": "alice@example.com"
    }
]

We can define a structure slice corresponding to the JSON array:

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

type PersonList []Person

Then , we can use the json.Unmarshal() function to parse the JSON array into slices:

import (
    "encoding/json"
    "fmt"
)

func main() {
    jsonData := []byte(`[
        {
            "name": "John",
            "age": 25,
            "email": "john@example.com"
        },
        {
            "name": "Alice",
            "age": 28,
            "email": "alice@example.com"
        }
    ]`)

    var personList PersonList
    err := json.Unmarshal(jsonData, &personList)
    if err != nil {
        fmt.Println("解析JSON数据失败:", err)
        return
    }

    for i, person := range personList {
        fmt.Printf("用户%d:
", i+1)
        fmt.Println("名称:", person.Name)
        fmt.Println("年龄:", person.Age)
        fmt.Println("邮箱:", person.Email)
        fmt.Println("---------")
    }
}

The output result is:

用户1:
名称: John
年龄: 25
邮箱: john@example.com
---------
用户2:
名称: Alice
年龄: 28
邮箱: alice@example.com
---------

4. Summary
Using Go language The encoding/json package makes it easy to parse the JSON data returned by the API. We only need to define the structure corresponding to the JSON data, and then use the json.Unmarshal() function to parse the JSON data into a Go language data structure. In this way, we can easily process the data obtained from the API, making the web application more powerful and flexible.

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