Optional body for POST requests

[vamshiaruru]

Hi! I have been using httpin for a while now and it has been an excellent library. However, I recently noticed that one of my post endpoints didn't have any payload defined, and now I need to add an optional json payload to it (optional because it is imperative I don't break backwards compatibility). This is the sample input type I have:

type RegisterAttendance struct {
	Slug string                   `in:"path=slug" validate:"required"`
}

I need to change it to

type RegisterPayload struct{
	VerifiedBy *string                   `json:"verifiedBy"`
}
type RegisterAttendance struct {
	Slug string                   `in:"path=slug" validate:"required"`
	Payload RegisterPayload `in:"body=json"`
}

However doing this means I can no longer make a post call with empty body. I mandatorily have to send {} as the payload. If I don't send any request body, I get the following error:

 failed: execute directive \"body\" with args [json] failed: EOF

We have clients that have been making calls without sending any request body to this endpoint, and I can't break those calls. If I was doing this without HTTPIN, I'd check of EOF while decoding JSON explicitly. Is there a way I can get this working with HTTPIN?

Thanks for the help!

[vamshiaruru]

I tried this

type OptionalJsonDecoder struct{}

func (o *OptionalJsonDecoder) Decode(src io.Reader, dst interface{}) error {
	err := json.NewDecoder(src).Decode(dst)
	if errors.Is(err, io.EOF) {
		return nil
	}
	return err
}

httpin.RegisterBodyDecoder("optionalJson", &OptionalJsonDecoder{}) // in init

but that doesn't seem to be working. I am getting

panic: httpin: unknown body type: "optionaljson"

[vamshiaruru]

never mind, it looks like both the tag and the first argument of RegisterBodyDecoder have to be lowercased. It works this way. Is it the best way?

[ggicci]

Sorry for the late response. I would like to look into this issue when I have time. I will keep it open.

[ggicci]

The body tag is designed to be case-insensitive because I didn't see a value of distinguishing json and JSON. By looking into the code, I believe in the latest version, we don't need to use the lowercase name of body in the tag.

If you register a body serializer by using optionalJson, internally a body format optionaljson is registerred. And in the tags, you can use both optionalJson and optionaljson, or even OptionalJSON, the latest version should not complain about this.

[ggicci]

By inspecting the "EOF issue", IMO, this error is expected for the bulitin json body directive. Because semantically, the body=json directive just indicates we expect the request body to be a valid JSON input. An empty stream is an invalid JSON input, so the EOF error should and must be raised. I don't want to break it.

So I think the optionalJson custom body format fits this case perfectly.