How to Get JSON Data from API Using Golang

This article guides you on how to retrieve JSON data from an API using the Golang programming language, helping you better understand how to interact with web services.

In this article, we will use the net/http package to send a GET request to an API and handle the returned JSON data. The code snippet will illustrate how to perform this in a clear and detailed manner.

package main

import (
    "encoding/json"
    "fmt"
    "net/http"
)

func main() {
    // API endpoint
    url := "https://api.example.com/data"

    // Send a GET request
    response, err := http.Get(url)
    if err != nil {
        fmt.Println("Error sending request:", err)
        return
    }
    defer response.Body.Close()

    // Check the status code
    if response.StatusCode == 200 {
        var data map[string]interface{}
        // Decode JSON data
        if err := json.NewDecoder(response.Body).Decode(&data); err != nil {
            fmt.Println("Error decoding data:", err)
            return
        }
        fmt.Println(data)
    } else {
        fmt.Printf("Error: %d\n", response.StatusCode)
    }
}

Detailed explanation

1. package main: Declare the main package of the program.
2. import (...): Import necessary packages, including encoding/json to work with JSON and net/http to send HTTP requests.
3. url := "https://api.example.com/data": Set the url variable to the address of the API you want to access.
4. response, err := http.Get(url): Send a GET request to the API and store the response in the response variable, while checking for errors.
5. defer response.Body.Close(): Ensure that the response body will be closed when the function ends.
6. if response.StatusCode == 200: Check if the request was successful (status code 200 indicates success).
7. var data map[string]interface{}: Declare the data variable to store the JSON data.
8. if err := json.NewDecoder(response.Body).Decode(&data); err != nil: Decode the JSON data from the response body into the data variable while checking for errors.
9. fmt.Println(data): Print the data to the console.
10. else: fmt.Printf("Error: %d\n", response.StatusCode): If there’s an error, print the error code for troubleshooting.

System Requirements

• Golang version: 1.12 or later

How to install the libraries needed to run the Golang code above

You do not need to install any external libraries as the net/http and encoding/json packages are standard packages available in Golang.

Tips

• Make sure you understand how the API you are calling works.
• Check the API documentation for usage details and required parameters.