README: fixing examples in creating token with claims

[dennybiasiolli]

No description provided.

[dennybiasiolli]

This will help copy-pasters in creating a new token using provided claims, otherwise the claims variable in the example is never used

[iSLC]

Doesn't this break the code tho? because now token is used before it was created.

Ex:

	// Set claims ('token' does not exist here)
	claims := token.Claims.(jwt.MapClaims)
	//...
	// Create token
	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)

[dennybiasiolli]

@iSLC you are right, in this case we can use the example from the official documentation: https://pkg.go.dev/github.com/golang-jwt/jwt#example-NewWithClaims-CustomClaimsType

Something like this:

mySigningKey := []byte("AllYourBase")

type MyCustomClaims struct {
	Foo string `json:"foo"`
	jwt.StandardClaims
}

// Create the Claims
claims := MyCustomClaims{
	"bar",
	jwt.StandardClaims{
		ExpiresAt: 15000,
		Issuer:    "test",
	},
}

token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
ss, err := token.SignedString(mySigningKey)
fmt.Printf("%v %v", ss, err)

[iSLC]

@dennybiasiolli yes you are correct. thanks for the prompt reply. I'm a bit new to golang.

For future reference jwt.StandardClaims appears to be deprecated (or to be) and the recommended approach is to use jwt.RegisteredClaims now. And looking at the source I can see why (it uses proper types for standard claims).

Leaving this here for reference:

package main

import (
	"fmt"
	"time"
	"github.com/golang-jwt/jwt/v4"
)

type MyCustomClaims struct {
	Foo string `json:"foo"`
	jwt.RegisteredClaims
}

func main() {
	mySigningKey := []byte("AllYourBase")

	// Create the Claims
	claims := MyCustomClaims{
		"bar",
		jwt.RegisteredClaims{
			ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 12)),
			Issuer:    "test",
		},
	}

	token := jwt.NewWithClaims(jwt.SigningMethodHS256, claims)
	ss, err := token.SignedString(mySigningKey)
	fmt.Printf("%v %v", ss, err)
}

[dennybiasiolli]

thanks @iSLC , let's follow up in #66