async calls in go using channels

go-async-api-call.go

package main

import (
	"fmt"
	"io/ioutil"
	"net/http"
)

type Message struct {
	Error  error
	Result string
}

func getURL(url string) chan Message {
	ch := make(chan Message)
	sendError := func(err error) {
		ch <- Message{
			Result: "",
			Error:  err}
	}

	go func() {
		defer close(ch)

		result, err := http.Get(url)

		if err != nil {
			sendError(err)
			return
		}

		defer result.Body.Close()

		bytes, err := ioutil.ReadAll(result.Body)

		if err != nil {
			sendError(err)
			return
		}

		ch <- Message{
			Error:  err,
			Result: string(bytes)}
	}()
	return ch
}

func main() {
	ch1 := getURL("https://jsonplaceholder.typicode.com/posts/2")
	ch2 := getURL("https://jsonplaceholder.typicode.com/posts/1")

	result1 := <-ch1
	result2 := <-ch2

	if result1.Error != nil || result2.Error != nil {
		fmt.Println("Failed to perform fetch")
		fmt.Printf("Error1 %v \n", result1.Error)
		fmt.Printf("Error2 %v \n", result2.Error)
		return
	}
	fmt.Printf("result1 %v \n", result1.Result)
	fmt.Printf("result2 %v \n", result2.Result)
}