Golang Development, CODEX

Make an HTTP GET/POST Request in Golang

Making REST API requests and handling responses

Sukhpal Saini

Published in

CodeX

3 min readMar 19, 2021

HTTP Requests are the bread and butter of any application. In this example, I will show you how you can make a GET/POST request using Golang.

We will use the jsonplaceholder.typicode.com API to make sample requests to.

Making a GET Request

package mainimport (
 "io/ioutil"
 "log"
 "net/http"
)func main() {
  resp, err := http.Get("https://jsonplaceholder.typicode.com/todos/1")
  
  if err != nil {
     log.Printf("Request Failed: %s", err)
     return
  }  defer resp.Body.Close()
  body, err := ioutil.ReadAll(resp.Body)  if err != nil {
     log.Printf("Reading body failed: %s", err)
     return
  }  // Log the request body 
  bodyString := string(body)
  log.Print(bodyString)
}

Making a GET Request with Params

Let’s look at how we can add URL params to our previous GET request. We can pass a userId to get the posts by that user.

package mainimport (
 "encoding/json"
 "fmt"
 "io/ioutil"
 "log"
 "net/http"
 "net/url"
)type Posts []struct {
 Userid int    `json:"userId"`
 ID     int    `json:"id"`
 Title  string `json:"title"`
 Body   string `json:"body"`
}func main() {
  params := url.Values{}
  params.Add("userId", "1")  resp, err := http.Get("https://jsonplaceholder.typicode.com/posts?" +params.Encode())  if err != nil {
     log.Printf("Request Failed: %s", err)
     return
  }
  defer resp.Body.Close()
  body, err := ioutil.ReadAll(resp.Body)  // Log the request body  
  bodyString := string(body)
  log.Print(bodyString)  // Unmarshal result
  posts := Posts{}
  err = json.Unmarshal(body, &posts)
  if err != nil {
     log.Printf("Reading body failed: %s", err)
     return
  }  log.Printf("The title of the first post is %s", posts[0].Title)
}

We can also marshal the JSON response into a collection of post structs. For reference, the JSON response from the API looks like this:

[
  {
    "userId": 1,
    "id": 1,
    "title": "sunt aut facere repellat provident occaecati excepturi optio reprehenderit",
    "body": "quia et suscipit suscipit recusandae consequuntur expedita et cum reprehenderit molestiae ut ut quas totam nostrum rerum est autem sunt rem eveniet architecto"
  }
]

Making a POST Request

Similarly, we can also make a POST request with body params to create a post using the API.

package mainimport (
 "encoding/json"
 "io/ioutil"
 "log"
 "net/http"
 "net/url"
)type Post struct {
 Userid string `json:"userId"`
 ID     int    `json:"id"`
 Title  string `json:"title"`
 Body   string `json:"body"`
}func main() {
  params := url.Values{}
  params.Add("title", "foo")
  params.Add("body", "bar")
  params.Add("userId", "1")resp, err := http.PostForm("https://jsonplaceholder.typicode.com/posts",
  params) if err != nil {   
   log.Printf("Request Failed: %s", err)
   return
 }  defer resp.Body.Close()
  body, err := ioutil.ReadAll(resp.Body)  // Log the request body 
  bodyString := string(body)
  log.Print(bodyString)  // Unmarshal result
  post := Post{}
  err = json.Unmarshal(body, &post)
  if err != nil {
     log.Printf("Reading body failed: %s", err)
     return
  }
  
  log.Printf("Post added with ID %d", post.ID)
}

The response from the API POST request looks like this:

{
  id: 101,
  title: 'foo',
  body: 'bar',
  userId: 1
}

There you have it. Now you can access data all across the web using GET/POST requests with Golang.

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