FormJSON is a net/http handler implementing content negotiation for posted data in order to transparently expose posted JSON as if it was application/x-www-form-urlencoded. The posted data is then available using built-in r.FormValue("key")'s http.Request method.

To match capabilities of application/x-www-form-urlencoded, only single depth JSON object with string as keys and values is supported.

package main

import (
    "net/http"
    "fmt"

    "github.com/rs/formjson"
)

func main() {
    h := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        body := fmt.Sprintf("Hello %s!", r.FormValue("name"))
        w.Write([]byte(body))
    })

    handler := formjson.Handler(h)
    http.ListenAndServe(":8080", handler)
}

Then this request:

curl -H "Content-Type:application/json" -d '{"name":"World"}' :8080

is now equivalent to this one:

curl -d name=World :8080

All source code is licensed under the MIT License.