When using gin-contrib/cors middleware directly in the default router, it works perfectly fine for any url, but when I create a group using r.Group(“/api”), the cors does not apply to any of the route in that group.

When checking the response headers, I’ve found that when using group router, the ‘access-control-allow-origin’ is not set. I can still manually set the header and it works, but the cors middleware just seems to not be working at all.

If I just set all my routes on the default router, everything works flawlessly.

I’ve tried to set the middleware to the root router:

func main() {
        // other code
    r := gin.Default()
    r.Use(cors.Default())
    apiRouter := r.Group("/api")

    apiRouter.GET("/record", func(ctx *gin.Context) {
        // other code
    })
    r.Run("127.0.0.1:3000")
}

To the group router:

func main() {
        // other code

    r := gin.Default()
    apiRouter := r.Group("/api")
    apiRouter.Use(cors.Default())

    apiRouter.GET("/record", func(ctx *gin.Context) {
        // other code
    })


    r.Run("127.0.0.1:3000")
}

or both, but all of them failed.

It works when the routes are set on the default router:

func main() {
        // other code
    r := gin.Default()
    r.Use(cors.Default())

    r.GET("/api/record", func(ctx *gin.Context) {
        // other code
    })
    r.Run("127.0.0.1:3000")
}

(btw, I’ve seen people talked about tailing ‘/’ in group route before, but sadly it is not the cause of this problem)