Access the underlying request body

[chriskolenko]

I'm trying at implement TUS (Resumable Upload) https://tus.io/protocols/resumable-upload.html

The Patch method requires access to the Request Body to get the raw bytes.

Is there anyway to get access to the Request Body in the input?

[vearutop]

Hi, you can implement request.Loader on your input structure to take over request decoding (and validation).

	// Loader loads data from http.Request.
	//
	// Implement this interface on a pointer to your input structure to disable automatic request mapping.
	Loader interface {
		LoadFromHTTPRequest(r *http.Request) error
	}

[chriskolenko]

Thank you. That'll work.

[chriskolenko]

Using the decoder factory it's missing the custom mappers for the request. So I'm missing any path fields

I.E.

type PatchTusInput struct {
	Id           uuid.UUID `path:"id" required:"true"`
	ContentType  string    `header:"Content-Type" required:"true"`
	UploadLength *int64    `header:"Upload-Length"`
	UploadOffset int64     `header:"Upload-Offset" required:"true"`
}

Everything else working fine.

[chriskolenko]

Ended up using this:

var patchTusInputDecoder nethttp.RequestDecoder

func init() {
	var decoderFactory = request.NewDecoderFactory()
	decoderFactory.ApplyDefaults = true
	decoderFactory.SetDecoderFunc(rest.ParamInPath, chirouter.PathToURLValues)

	patchTusInputDecoder = decoderFactory.MakeDecoder(http.MethodPatch, new(PatchTusInput), nil)
}

[chriskolenko]

Also for people reading along, beware of the stack overflow because of a recursive loader.

To avoid the issue I did the following:

type PatchTusInput struct {
	// The ID of the mass payout
	Id           uuid.UUID `path:"id" required:"true"`
	ContentType  string    `header:"Content-Type" required:"true"`
	UploadLength *int64    `header:"Upload-Length"`
	UploadOffset int64     `header:"Upload-Offset" required:"true"`
}

type PatchTusInputWithBody struct {
	PatchTusInput

	RawBody io.ReadCloser
}

func (tr *PatchTusInputWithBody) LoadFromHTTPRequest(r *http.Request) error {
	tr.RawBody = r.Body
	return patchTusInputDecoder.Decode(r, &tr.PatchTusInput, nil)
}

[vearutop]

You can also reuse resources initialized in web.Service and prepare JSON schema validator.

var (
	patchTusInputDecoder   nethttp.RequestDecoder
	patchTusInputValidator rest.Validator
)

type PatchTusInput struct {
	// The ID of the mass payout
	Id           uuid.UUID `path:"id" required:"true"`
	ContentType  string    `header:"Content-Type" required:"true"`
	UploadLength *int64    `header:"Upload-Length" minimum:"0"`
	UploadOffset int64     `header:"Upload-Offset" required:"true" minimum:"0"` // JSON schema constraint added for example.
}

type PatchTusInputWithBody struct {
	PatchTusInput

	RawBody io.ReadCloser
}

func (tr *PatchTusInputWithBody) LoadFromHTTPRequest(r *http.Request) error {
	tr.RawBody = r.Body
	return patchTusInputDecoder.Decode(r, &tr.PatchTusInput, patchTusInputValidator)
}

func main() {
	s := web.DefaultService()

	// Any additional instrumentation...

	patchTusInputDecoder = s.DecoderFactory.MakeDecoder(http.MethodPatch, new(PatchTusInput), nil)
	patchTusInputValidator = jsonschema.NewFactory(s.OpenAPICollector, s.OpenAPICollector).
		MakeRequestValidator(http.MethodPatch, new(PatchTusInput), nil)

	// ....

[vearutop]

In a recently updated version, you can now access the body much easier, just by implementing request.Setter on the input, this would not prevent standard decoding/validation flow.