Golang : Read, Write(Create) and Delete Cookie example
Got an email from a reader asking for a more elaborated example of how to read, write(create) and delete a cookie in Golang. Somehow the previous tutorial on dropping a cookie to visitor's browser wasn't detailed enough.
Alright, a fair request.
Below is an example of how to read, write/create and delete a cookie within a simple webserver.
NOTE: IF you are planning to read, write/create and delete multiple cookies. See how to use net/http/cookiejar
tutorial at https://www.socketloop.com/tutorials/golang-storing-cookies-in-http-cookiejar-example
Here you go!
package main
import (
"net/http"
)
func SayHelloWorld(w http.ResponseWriter, r *http.Request) {
html := "Hello World! "
w.Write([]byte(html))
}
func ReadCookie(w http.ResponseWriter, r *http.Request) {
c, err := r.Cookie("ithinkidroppedacookie")
if err != nil {
w.Write([]byte("error in reading cookie : " + err.Error() + "\n"))
} else {
value := c.Value
w.Write([]byte("cookie has : " + value + "\n"))
}
}
// see https://golang.org/pkg/net/http/#Cookie
// Setting MaxAge<0 means delete cookie now.
func DeleteCookie(w http.ResponseWriter, r *http.Request) {
c := http.Cookie{
Name: "ithinkidroppedacookie",
MaxAge: -1}
http.SetCookie(w, &c)
w.Write([]byte("old cookie deleted!\n"))
}
func CreateCookie(w http.ResponseWriter, r *http.Request) {
c := http.Cookie{
Name: "ithinkidroppedacookie",
Value: "thedroppedcookiehasgoldinit",
MaxAge: 3600}
http.SetCookie(w, &c)
w.Write([]byte("new cookie created!\n"))
}
func main() {
mux := http.NewServeMux()
mux.HandleFunc("/", SayHelloWorld)
mux.HandleFunc("/readcookie", ReadCookie)
mux.HandleFunc("/deletecookie", DeleteCookie)
mux.HandleFunc("/createcookie", CreateCookie)
http.ListenAndServe(":8080", mux)
}
Now, to see how the cookie is being created, read and deleted. You need to follow this sequence.
- Run the program and point your web browser to
localhost:8080
- Change the URL to
localhost:8080/createcookie
to create new cookie. - Read the cookie by changing to
localhost:8080/createcookie
. - Finally, delete the cookie by changing to
localhost:8080/deletecookie
.
If you happen to view with Chrome browser, open up the inspector to see the cookie value
Hope this helps!
References:
https://www.socketloop.com/tutorials/golang-http-server-example
See also : Golang : Storing cookies in http.CookieJar example
By Adam Ng
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