Go Gin Setting and Accessing context value from middleware - rest

Question

I am trying to set my user context, in the middleware then trying to check if user have permission in other handler functions. But for some reason when I try to access the user from context it is coming back as nils. The middleware code seems to be working, when I pass a valid jwt token, it is showing the user is being set in context in the middleware function. But as soon as I hit getCurrentUser function it says it's nil.
Here is the code:
Middleware
// Middleware wraps the request with auth middleware
func Middleware(path string, sc *cfg.Server, orm *orm.ORM) gin.HandlerFunc {
logger.Info("[Auth.Middleware] Applied to path: ", path)
return gin.HandlerFunc(func(c *gin.Context) {
t, err := ParseToken(c, sc)
if err != nil {
authError(c, err)
} else {
if claims, ok := t.Claims.(jwt.MapClaims); ok {
if claims["exp"] != nil {
issuer := claims["iss"].(string)
userid := claims["jti"].(string)
email := claims["email"].(string)
if claims["aud"] != nil {
audiences := claims["aud"].(interface{})
logger.Warnf("\n\naudiences: %s\n\n", audiences)
}
if claims["alg"] != nil {
algo := claims["alg"].(string)
logger.Warnf("\n\nalgo: %s\n\n", algo)
}
if user, err := orm.FindUserByJWT(email, issuer, userid); err != nil {
authError(c, ErrForbidden)
} else {
if user != nil {
c.Request = addToContext(c, consts.ProjectContextKeys.UserCtxKey, user)
logger.Debug("User: ", user.ID)
}
c.Next()
}
} else {
authError(c, ErrMissingExpField)
}
} else {
authError(c, err)
}
}
})
}
routes
// User routes
func User(sc *cfg.Server, r *gin.Engine, orm *orm.ORM) error {
// OAuth handlers
mw := auth.Middleware(sc.VersionedEndpoint("/user/:id"), sc, orm)
g := r.Group(sc.VersionedEndpoint("/user"))
g.Use(mw)
g.GET("/:id", mw, user.Get(orm))
g.PUT("/:id", mw, user.Update(orm))
g.POST("/", user.Create(orm))
return nil
}
handler
func Get(orm *orm.ORM) gin.HandlerFunc {
return func(ctx *gin.Context) {
cu := getCurrentUser(ctx)
if ok, err := cu.HasPermission(consts.Permissions.Create, consts.EntityNames.Users); !ok || err != nil {
ctx.String(http.StatusUnauthorized, "BAD")
}
}
}
addToContext:
func addToContext(c *gin.Context, key consts.ContextKey, value interface{}) *http.Request {
return c.Request.WithContext(context.WithValue(c.Request.Context(), key, value))
}
getCurrentUser:
func getCurrentUser(ctx context.Context) *dbm.User {
cu := ctx.Value(utils.ProjectContextKeys.UserCtxKey).(*dbm.User)
logger.Debugf("currentUser: %s - %s", cu.Email, cu.ID)
return cu
}

Answer 1

The problem is that you're storing the user in one context but then you're attempting to retrieve the user from another context. The value *gin.Context and the value *gin.Context.Request.Context are two separate context values.
You're using the Request's context to store the user:
c.Request.WithContext(context.WithValue(c.Request.Context(), key, value))
And then you're using the gin context to retrieve the user:
func getCurrentUser(ctx context.Context) *dbm.User {
cu := ctx.Value(utils.ProjectContextKeys.UserCtxKey).(*dbm.User)
// ...
func Get(orm *orm.ORM) gin.HandlerFunc {
return func(ctx *gin.Context) {
cu := getCurrentUser(ctx) // here you're passing *gin.Context to the function.
// ...
So to fix that change the value that's passed in to the getCurrentUser call to:
func Get(orm *orm.ORM) gin.HandlerFunc {
return func(ctx *gin.Context) {
cu := getCurrentUser(ctx.Request.Context())
if ok, err := cu.HasPermission(consts.Permissions.Create, consts.EntityNames.Users); !ok || err != nil {
ctx.String(http.StatusUnauthorized, "BAD")
}
}
}