It seems like with every release, Go becomes better and better. Go 1.22 is no different. There are a lot of great advancements in this new release, but one in particular is really noteworthy: Improved route handling. The first advancement I want to highlight is getting route values. Before Go 1.22, this was either difficult to do with the standard library (lots of parsing!), or you had to use an external library. And if you’ve been in the Go world for any amount of time, you probably already know that us Go developers really like to just use the standard library.
Now with Go 1.22 we have the ability to pull route values easily!
Let’s take this example: We want to expose a /users API that either lists out usernames, or it allows you specify a user with /users/<name> and you get some information about them.
I defined my routes like this:
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http.HandleFunc("/users/{name}", getUserHandler)
http.HandleFunc("/users", getUserHandler)
And then I’m able to access the name value in my handler getUserHandler:
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username := r.PathValue("name")
If that’s empty, I know the path /users was used, and just dump out all the users. I really like this new, and much easier way, to get values from routes! Full working server code can be found below.
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package main
import (
"encoding/json"
"fmt"
"net/http"
"os"
)
type user struct {
Name string `json:"name"`
FavoriteColor string `json:"favoriteColor"`
}
var allUsers = []user{
{Name: "testuser1", FavoriteColor: "green"},
{Name: "testuser2", FavoriteColor: "grey"},
}
func getUserHandler(w http.ResponseWriter, r *http.Request) {
username := r.PathValue("name")
if username == "" {
allUsersJSON, _ := json.Marshal(allUsers)
w.Write([]byte(allUsersJSON))
return
}
for _, user := range allUsers {
if user.Name == username {
userJSON, _ := json.Marshal(user)
w.Write([]byte(userJSON))
return
}
}
w.WriteHeader(http.StatusBadRequest)
w.Write([]byte(fmt.Sprintf("unknown user: %s", username)))
}
func main() {
http.HandleFunc("/users/{name}", getUserHandler)
http.HandleFunc("/users", getUserHandler)
fmt.Println("Running server...")
if err := http.ListenAndServe(":8000", nil); err != nil {
fmt.Printf("Error running server: %v\n", err)
os.Exit(1)
}
}