从多部分POST中提取表单值

I've been struggle a lot with extracting form values from a multipart request form in Go. The form contains x number of key : values and also a file.

The parts do exist in the BODY when I print the whole body.

Alternative 1:

func(w http.ResponseWriter, r *http.Request) {
    r.ParseMultipartForm(0)

    fmt.Println(r.FormValue("key"))
}

This returns only empty values.

Alternative 2:

My second approach was to do something like this with MultipartReader():

Read request payload in Go?

However, this give me "unexpected EOF" before getting the last value with FormValue(). It does however print 9/10 values.

Can someone with more experience with Go give some hints how to fix this? And yes, I think I've searched the whole net for a solution now. Nothing seems to work.

Thanks.