PANIC Value not found for type *web.Context

[xyproto]

Hi,

The "martini" branch in one of my repositories has an example application that panics when visited, that did not panic with hoisie/web:

https://github.com/xyproto/browserspeak/tree/martini

One way of trying it out

go get github.com/martini-contrib/web
go get github.com/go-martini/martini
mkdir -p $GOPATH/src/github.com/xyproto
cd $GOPATH/src/github.com/xyproto
git clone https://github.com/xyproto/browserspeak.git -b martini
cd browserspeak/example
go build
PORT=8080 ./example

Visiting http://localhost:8080/test.svg works, but http://localhost:8080/ gives the following backtrace:

PANIC

Value not found for type *web.Context

/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/router.go:352 (0x43dd08)
    (*routeContext).run: panic(err)
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/router.go:229 (0x43d102)
    (*route).Handle: context.run()
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/router.go:112 (0x43c13c)
    (*router).Handle: route.Handle(context, res)
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/martini.go:111 (0x43e5d0)
    Router.Handle.fm: m.Action(r.Handle)
/opt/go/src/pkg/runtime/asm_amd64.s:340 (0x4242b2)
    call64: CALLFN(call64, 64)
/opt/go/src/pkg/reflect/value.go:474 (0x464fbb)
    Value.call: call(fn, ptr, uint32(size))
/opt/go/src/pkg/reflect/value.go:345 (0x4640ad)
    Value.Call: return v.call("Call", in)
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/codegangsta/inject/inject.go:102 (0x4b0ff4)
    (*injector).Invoke: return reflect.ValueOf(f).Call(in), nil
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/martini.go:165 (0x43a742)
    (*context).run: _, err := c.Invoke(c.handler())
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/martini.go:156 (0x43a69b)
    (*context).Next: c.run()
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/recovery.go:140 (0x43eaf6)
    func.004: c.Next()
/opt/go/src/pkg/runtime/asm_amd64.s:339 (0x424252)
    call32: CALLFN(call32, 32)
/opt/go/src/pkg/reflect/value.go:474 (0x464fbb)
    Value.call: call(fn, ptr, uint32(size))
/opt/go/src/pkg/reflect/value.go:345 (0x4640ad)
    Value.Call: return v.call("Call", in)
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/codegangsta/inject/inject.go:102 (0x4b0ff4)
    (*injector).Invoke: return reflect.ValueOf(f).Call(in), nil
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/martini.go:165 (0x43a742)
    (*context).run: _, err := c.Invoke(c.handler())
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/martini.go:156 (0x43a69b)
    (*context).Next: c.run()
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/logger.go:25 (0x43e392)
    func.001: c.Next()
/opt/go/src/pkg/runtime/asm_amd64.s:340 (0x4242b2)
    call64: CALLFN(call64, 64)
/opt/go/src/pkg/reflect/value.go:474 (0x464fbb)
    Value.call: call(fn, ptr, uint32(size))
/opt/go/src/pkg/reflect/value.go:345 (0x4640ad)
    Value.Call: return v.call("Call", in)
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/codegangsta/inject/inject.go:102 (0x4b0ff4)
    (*injector).Invoke: return reflect.ValueOf(f).Call(in), nil
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/martini.go:165 (0x43a742)
    (*context).run: _, err := c.Invoke(c.handler())
/uio/kant/usit-uait-u1/rodseth/go/src/github.com/go-martini/martini/martini.go:69 (0x439a63)
    (*Martini).ServeHTTP: m.createContext(res, req).run()
/opt/go/src/pkg/net/http/server.go:1597 (0x48a26e)
    serverHandler.ServeHTTP: handler.ServeHTTP(rw, req)
/opt/go/src/pkg/net/http/server.go:1167 (0x488277)
    (*conn).serve: serverHandler{c.server}.ServeHTTP(w, w.req)
/opt/go/src/pkg/runtime/proc.c:1394 (0x417ab0)
    goexit: runtime·goexit(void)

I can not see any references to my own code, so I'm having a hard time pinpointing where this error lies. Any help is appreciated.

Best regards,
Alexander Rødseth
@gissues:{"order":50,"status":"done"}

[mickelsonm]

Hi @xyproto ! I think you may have overlooked a couple things with your code.

Here's how you have to go about using *web.Context, which in your case didn't have value because you didn't use it! :)

See example below:

    func svgGenerator(ctx *web.Context){
        page := svgPage()
        ctx.WriteString(page.String())
    }

    func defaultHandler(ctx *web.Context){
        ctx.WriteString("TODO: Implement me!")
    }

    func main() {
        fmt.Println("BrowserSpeak Version:", browserspeak.Version)

        m := martini.Classic()
        m.Use(web.ContextWithCookieSecret(""))

        // Connect /test.svg with svgGenerator
        m.Get("/test", svgGenerator)

        //TODO: implement a root handler
        m.Get("/", defaultHandler)

        m.Run()
    }

Also, make sure to implement a root handler! It doesn't know how to handle / on its own...

Hope this helps!

[xyproto]

Thank you! I will look into this.