Constants to Use When Checking for HTTP Status Codes

Go has useful constants in the net/http package that can make your code more readable when checking for status codes in responses.

For example, instead of writing something like

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if resp.StatusCode == 200 {
    // do something if the status code is 200
}

You can write

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if resp.StatusCode == http.StatusOK {
    // do something if the status code is 200
}

Unfortunately the link doesn’t show any full, working examples. So here’s an example covering some of the more common http status codes that you can use and modify as needed.

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package main

import (
	"fmt"
	"log"
	"net/http"
)

func main() {
	resp, err := http.Get("https://example.com")
	if err != nil {
		log.Fatalf("error: %v", err)
	}

	defer resp.Body.Close()

	// Status code 200
	if resp.StatusCode == http.StatusOK {
		fmt.Println("ok!")
	}

	// Status code 301
	if resp.StatusCode == http.StatusMovedPermanently {
		fmt.Println("moved permanently")
	}

	// Status code 403
	if resp.StatusCode == http.StatusForbidden {
		fmt.Println("forbidden")
	}

	// Status code 404
	if resp.StatusCode == http.StatusNotFound {
		fmt.Println("not found")
	}

	// Status code 429
	if resp.StatusCode == http.StatusTooManyRequests {
		fmt.Println("too many requests")
	}

	// Status code 500
	if resp.StatusCode == http.StatusInternalServerError {
		fmt.Println("internal server error")
	}

	// Status code 502
	if resp.StatusCode == http.StatusBadGateway {
		fmt.Println("bad gateway")
	}
}

Turning HTTP Status Codes into Messages with http.StatusText()

There’s also a function http.StatusText() that allows you to pass in status codes and get a message for logging purposes or displaying to users. You can see all the responses in the source code here, it’s a bunch of case statements.

For example, let’s say we want to display a message if we don’t get a 200 status code. Instead of writing code to print out a different message depending on the status code value, we can use the http.StatusText() function:

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package main

import (
	"fmt"
	"log"
	"net/http"
)

func main() {
	resp, err := http.Get("https://example.com/404") // this URL returns a 404 status code
	if err != nil {
		log.Fatalf("error: %v", err)
	}

	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		// if it's not 200, print out a message depending on the status code
		fmt.Println(http.StatusText(resp.StatusCode)) // http.StatusText() is called here
	}
}

$ go run example.go

Not Found

Super convenient.

References