Problem with optional fields is not solved

[uralm1]

As I see, your fork doesn't solve the problem with optional fields in api structures and json.

Let's see.

sendMessage(... LinkPreviewOptions::Ptr linkPreviewOptions = nullptr ...)

Ok, we can remove LinkPreviewOptions structure from output json COMPLETELY when it null.

class LinkPreviewOptions {
  
  public:
    ⦙ typedef std::shared_ptr<LinkPreviewOptions> Ptr;
  
    ⦙ /**
    ⦙ ⦙* @brief Optional. True, if the link preview is disabled
    ⦙ ⦙*/
    ⦙ bool isDisabled;
  
    ⦙ /**
    ⦙ ⦙* @brief Optional. URL to use for the link preview.
    ⦙ ⦙*
    ⦙ ⦙* If empty, then the first URL found in the message text will be used
    ⦙ ⦙*/
    ⦙ std::string url;
  
    ⦙ /**
    ⦙ ⦙* @brief Optional. True, if the media in the link preview is supposed to be shrunk; ignored if the URL is
    ⦙ ⦙*/
    ⦙ bool preferSmallMedia;

We cannot include only a PART of LinkPreviewOptions structure in output json. Thats why I suggest wrapping fields in boost::optional.
It's possible to check optionality from pointer field, but we cannot make optional bools, ints or strings (ok, strings - disputable).

class ReplyParameters {
  
  public:
    ⦙ typedef std::shared_ptr<ReplyParameters> Ptr;
  
    ⦙ /**
    ⦙ ⦙* @brief Identifier of the message that will be replied to in the current chat, or in the chat chatId if 
    ⦙ ⦙*/
    ⦙ std::int32_t messageId;
  
    ⦙ /**
    ⦙ ⦙* @brief Optional. If the message to be replied to is from a different chat, unique identifier for the ch
    ⦙ ⦙*
    ⦙ ⦙* Not supported for messages sent on behalf of a business account.
    ⦙ ⦙*/
    ⦙ std::int64_t chatId;

Need to skip chatId.

DECLARE_PARSER_TO_JSON(ReplyParameters) {
    ⦙ JsonWrapper json;
    
    ⦙ if (object) {
    ⦙ ⦙ ⦙ json.put("message_id", object->messageId);
    ⦙ ⦙ ⦙ json.put("chat_id", object->chatId);

ChatId is always serialized as 0 if it was not assigned implicitly.

[uralm1]

Addition: I looked in metaprograming code in TgTypeParser.h, I think this serializers don't help the issue. Am I wrong?

is_initialized_with_default_constructor_v
is_assigned_by_hand traits can help :)

[uralm1]

I've made some research, how resulting json is generated, and found that json.put() uses heuristic hacks depended of value type to determine, include field to resulting json or not. It can generate incorrect results sometimes:
For example:

ReplyParameters.messageId = 0 generates json without messageId key, but messageId is NOT optional -> wrong,
ReplyParameters.chatId = 0 generates json without chatId key, chatId is optional -> right,
ReplyParameters.quote_entities - always generated as [] when is not set -> wrong
etc

Lack of possibility to include false for bool value, 0 for int value to resulting json is not good.

[Royna2544]

always generated as [] when is not set -> wrong

I guess this is easily fixable

0 generates json without messageId key, but messageId is NOT optional -> wrong,

For this, I'll probably have to think how-to
(Probably specializing JsonWrapper::put for std::optional, and wrapping the optional object all in std optional would fix it)

[Royna2544]

It should be fixed now as I wrapped really optional objects under std optional, can you try it?

[uralm1]

I'm experimenting with optional attributes here reo7sp#320, keep an eye there too.

Also wanted to add OptionalEmptyString<>, OptionalFalseBool<> attributes, but don't know how to differentiate it from Required types.

[Royna2544]

Meh, the one without jsoncpp is a mess, as i said before, doesn't work (gives a bad request) for createStickerSet or setBotCommands(Windows) etc, (Why even manually concat json string when there is jsoncpp or even nlohmann/json which is header only?) So I'm not interested.

OptionalEmptyString<>, OptionalFalseBool<>

And I think they should be wrapped in a empty struct tag, so they can be figured out with metaprogramming.

My updated code with std::optional doesn't enforce the required parameters to be set, but it will indeed put the required args in JSON now, so I think mine is the best solution.