panic: runtime error: invalid memory address or nil pointer dereference || r.body model

0
votes

I have problem newbie Go Programming like: invalid memory address or nil pointer dereference

Sometime I can resolve the problem, but this is make me confuse. this is the code in Handler level, I tried to implement ###p.repo.UpdateProfile() and data from r.body decode

//UpdateProfile handler
func (p *Profile) UpdateProfile(w http.ResponseWriter, r *http.Request) {
    var (
        errForm   models.ErrorForm
        resp      models.Response
        respError models.ErrorResponse
        errField  models.ErrField
        data      *models.EditProfile
    )

    userid := r.Context().Value(viper.GetString("token.userid"))
        
        errDecode := json.NewDecoder(r.Body).Decode(&data)

    errPayload := p.repo.UpdateProfile(r.Context(), data, userid)

    if errPayload.Error() == "username_exist" {
        respError.Message = "username already taken"
        respError.Status = 422
        lib.ResJSON(w, respError.Status, respError)
        return
    }
    lib.Catch(errPayload)

    resp.Data = ""
    resp.Message = "Success"
    resp.Status = 200

    lib.ResJSON(w, resp.Status, resp)
}

and the Method like:


func (m *mysqlProfileRepo) UpdateProfile(ctx context.Context, p *models.EditProfile, userid interface{}) error {
    query := ""
    var checkexist int

    row1, err1 := m.Conn.QueryContext(ctx, query, p.Username)
    if err1 != nil {
        return err1
    }

    for row1.Next() {
        if errSc1 := row1.Scan(&checkexist); errSc1 != nil {
            return errors.New("error_scan_db")
        }
    }

    if checkexist != 0 {
        return errors.New("username_exist")
    }

    query1 := ""
    query2 := ""

    stmts := []*lib.PipelineStmt{
        lib.NewPipelineStmt(query1, p.Image, p.Location, p.Link, p.Bio, p.Birthday, userid),
        lib.NewPipelineStmt(query2, p.Username, p.Fullname, userid),
    }

    errTrx := lib.WithTransaction(m.Conn, func(tx lib.Transaction) error {
        _, errRunPipe := lib.RunPipeline(tx, stmts...)
        return errRunPipe
    })

    if errTrx != nil {
        return errTrx
    }

    return nil
}

MyCode work well in database, the data successfully updated, but the response server is

panic: runtime error: invalid memory address or nil pointer dereference
2019/07/21 13:27:36 goroutine 8 [running]:
runtime/debug.Stack(0xc00028e100, 0x16b1a20, 0xc000094040)
    /usr/local/Cellar/go/1.12.6/libexec/src/runtime/debug/stack.go:24 +0x9d
github.com/go-chi/chi/middleware.Recoverer.func1.1(0xc00028e100, 0x16b6be0, 0xc000256280)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/middleware/recoverer.go:25 +0x9c
panic(0x155e7a0, 0x1a66a10)
    /usr/local/Cellar/go/1.12.6/libexec/src/runtime/panic.go:522 +0x1b5
audioo_api/handler.(*Profile).UpdateProfile(0xc000020030, 0x16b6be0, 0xc000256280, 0xc00028e200)
    /Users/rizaldinurmuhammad/go/src/audioo_api/handler/profile.go:73 +0x524
net/http.HandlerFunc.ServeHTTP(0xc000020050, 0x16b6be0, 0xc000256280, 0xc00028e200)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
audioo_api/lib/mid.Authenticate.func1.1(0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/audioo_api/lib/mid/auth.go:48 +0x71e
net/http.HandlerFunc.ServeHTTP(0xc00000e0a0, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi.(*ChainHandler).ServeHTTP(0xc000066140, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/chain.go:31 +0x52
github.com/go-chi/chi.(*Mux).routeHTTP(0xc0000a5f80, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/mux.go:425 +0x27f
net/http.HandlerFunc.ServeHTTP(0xc000020040, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi.(*Mux).ServeHTTP(0xc0000a5f80, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/mux.go:70 +0x451
github.com/go-chi/chi.(*Mux).Mount.func1(0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/mux.go:292 +0x127
net/http.HandlerFunc.ServeHTTP(0xc00000e0e0, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi.(*Mux).routeHTTP(0xc0000a59e0, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/mux.go:425 +0x27f
net/http.HandlerFunc.ServeHTTP(0xc0001db880, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi.(*Mux).ServeHTTP(0xc0000a59e0, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/mux.go:70 +0x451
github.com/go-chi/chi.(*Mux).Mount.func1(0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/mux.go:292 +0x127
net/http.HandlerFunc.ServeHTTP(0xc00000e180, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi.(*Mux).routeHTTP(0xc0000a5920, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/mux.go:425 +0x27f
net/http.HandlerFunc.ServeHTTP(0xc000020090, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
audioo_api/lib/mid.Limit.func1(0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/audioo_api/lib/mid/limit.go:79 +0xe5
net/http.HandlerFunc.ServeHTTP(0xc00000e1a0, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/cors.(*Cors).Handler.func1(0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/cors/cors.go:201 +0x1a4
net/http.HandlerFunc.ServeHTTP(0xc00000e1c0, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi/middleware.Recoverer.func1(0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/middleware/recoverer.go:35 +0x9f
net/http.HandlerFunc.ServeHTTP(0xc00000e1e0, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi/middleware.RedirectSlashes.func1(0x16b6be0, 0xc000256280, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/middleware/strip.go:53 +0x202
net/http.HandlerFunc.ServeHTTP(0xc00000e200, 0x16b6be0, 0xc000256280, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi/middleware.(*Compressor).Handler.func1.1(0x1f69180, 0xc000256240, 0xc00028e100)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/middleware/compress.go:190 +0x254
net/http.HandlerFunc.ServeHTTP(0xc00000e2c0, 0x1f69180, 0xc000256240, 0xc00028e100)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi/middleware.RequestLogger.func1.1(0x16b78a0, 0xc000226000, 0xc00028e000)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/middleware/logger.go:46 +0x291
net/http.HandlerFunc.ServeHTTP(0xc00009a210, 0x16b78a0, 0xc000226000, 0xc00028e000)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1995 +0x44
github.com/go-chi/chi.(*Mux).ServeHTTP(0xc0000a5920, 0x16b78a0, 0xc000226000, 0xc000154000)
    /Users/rizaldinurmuhammad/go/src/github.com/go-chi/chi/mux.go:82 +0x294
net/http.serverHandler.ServeHTTP(0xc00009c410, 0x16b78a0, 0xc000226000, 0xc000154000)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:2774 +0xa8
net/http.(*conn).serve(0xc0002ce640, 0x16b8aa0, 0xc000067340)
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:1878 +0x851
created by net/http.(*Server).Serve
    /usr/local/Cellar/go/1.12.6/libexec/src/net/http/server.go:2884 +0x2f4

I have tried to change context to implement database but the response still the same.

I wonder this problem related in r.body, but I dont know how to figure out

1
go
What are you doing with errDecode from. errDecode := json.NewDecoder(r.Body).Decode(&data) ? - ZAky
Define error if decode fail, I am not give all the code, I have handle this errDecode - James Rizaldi
The code you left out may be important. data is already a pointer. what is the line at audioo_api/handler/profile.go:73 and what post request middleware you have? - ZAky
in line 73, I call method p.repo.Updateprofile(). in this method, the "data" appear if I fmt.println(data) same as input in body request. You can see I block if username already exist, so far in this line code the server work well the response "Username already exist", but if passed the the server responses invali address BUT the data successfull updated in my DB. OMG :( - James Rizaldi
I tried to not use middleware authorized but, still the error still the same - James Rizaldi

1 Answers

0
votes

According to the package documentation for Body io.ReadCloser:

For client requests, a nil body means the request has no body, such as a GET request. For server requests, the Request Body is always non-nil.

You say, it's a server, so, it's always non-nil, thus the error is in the Decode call where you pass a pointer to the nil pointer.

data is a nil pointer, &data is a pointer to a nil pointer.

Solution if data is a non interface type, unless models package explicitly forbids new(EditProfile):

    data = new(models.EditProfile)
    errDecode := json.NewDecoder(r.Body).Decode(data)

If data is an interface, allocate a real value for it first, and again pass without a reference to Decode: errDecode := json.NewDecoder(r.Body).Decode(data)

And in the latter case also double check if you declare the right type *models.EditProfile.