how to break-out of middleware chain using Martini

[ORESoftware]

I put this question on SO and am looking for answers - this question may be based off a false assumption:

https://stackoverflow.com/questions/60679922/how-to-break-out-of-martini-middleware

but at the very least I have no idea how martini would know when to keep invoking the middleware chain and when not to? it wouldn't know even if you aleady set the http status code or wrote the response body, you may still want to keep writing in subsequent middleware funcs. someone please explain how to return early out of the chain.

Perhaps this is the best way to do it?

m.Use(func(c martini.Context, w http.ResponseWriter){

    if reqIsMalformed() {
        http.Error(w, "Bad request because xyz", 422)
        return;
    }

    c.Next()  // only invoke remaining middleware if the request is valid?

})

[ORESoftware]

I did some legwork and ran a test:

func check0() {
	return;
}

func check1(res http.ResponseWriter) string{
	return "1"
}

func check2(c martini.Context, res http.ResponseWriter) string{
	if true {
		return "hiii";
	}
	c.Next()
	return "2"
}

func check3(c martini.Context, res http.ResponseWriter) string{
	c.Next()
	return "3"
}

func check4(res http.ResponseWriter) {
	res.Write([]byte("4"))
}

func check5(c martini.Context, res http.ResponseWriter) string{
	res.Write([]byte("5.0"))
	c.Next()
	return "5.1"
}

func finish(res http.ResponseWriter){
	fmt.Println("in finish")
	res.Write([]byte("all done"))
}

func Routes(m *martini.ClassicMartini) {
        m.Get("/cp/meta/middleware0", check0, finish)
	m.Get("/cp/meta/middleware1", check1, finish)
	m.Get("/cp/meta/middleware2", check2, finish)
	m.Get("/cp/meta/middleware3", check3, finish)
	m.Get("/cp/meta/middleware4", check4, finish)
	m.Get("/cp/meta/middleware5", check5, finish)
}

the results I got:

GET /cp/meta/middleware0 => all done
GET /cp/meta/middleware1 => 1
GET /cp/meta/middleware2 => hiii
GET /cp/meta/middleware3 => all done3
GET /cp/meta/middleware4 => 4
GET /cp/meta/middleware5 => 5.0all done5.1

what surprised me is that the subsequent middleware (the finish() func) was not called for :

GET /cp/meta/middleware4

what is the reason for this? Other than that, the rule seems to be if the middleware func returns anything (return args length > 0), then no more middleware is called unless c.Next() is called of course).

Please document which scenarios cause middleware to stop being called and/or how to continue calling subsequent registered middleware.

[straightdave]

I add the Break() method for martini's context like this:

func (c *context) Break() {
	// skip other handlers plus one possible action
	c.index = len(c.handlers) + 1
	c.run()
}

This will skip the loop in func (c *context) run().