oat++ framework/Lobby

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

Also, maybe this has to do with the fact that the property i try to access in the BaseDto definition is itself a Dto

class HeaderDto : public oatpp::data::mapping::type::Object
{
DTO_INIT(HeaderDto, Object)

        DTO_FIELD(Int64, time);

    };

    class ResponseDto : public oatpp::data::mapping::type::Object 
    {
        DTO_INIT(ResponseDto, Object)

        DTO_FIELD(HeaderDto::ObjectWrapper, header);
    };

i try to access field "time" on ResponseDto object via field "header"

auto dto = ResponseDto::createShared();
dto->header->time = 0;

oat++

@oatpp_io_twitter

Hello @MJLHThomassen-Sorama , and welcome.
Let me double-check this. Will get back to you shortly.

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

Hey @oatpp_io_twitter , thanks!

oat++

@oatpp_io_twitter

Hey @MJLHThomassen-Sorama

please see the full working example:


#include "oatpp/parser/json/mapping/ObjectMapper.hpp"
#include "oatpp/core/macro/codegen.hpp"
#include <iostream>

#include OATPP_CODEGEN_BEGIN(DTO)

class MyBaseDto : public oatpp::data::mapping::type::Object {

  DTO_INIT(MyBaseDto, Object)

  DTO_FIELD(String, myBaseDtoField);

};

class HeaderDto : public MyBaseDto /* Should also extend a class here */ {

  DTO_INIT(HeaderDto, MyBaseDto)

  DTO_FIELD(Int64, time);

};

class ResponseDto : public oatpp::data::mapping::type::Object {

  DTO_INIT(ResponseDto, Object)

  DTO_FIELD(HeaderDto::ObjectWrapper, header) = HeaderDto::createShared(); // Don't forger to initialize object

};

#include OATPP_CODEGEN_END(DTO)

void run() {

  auto dto = ResponseDto::createShared();
  dto->header->time = 0;
  dto->header->myBaseDtoField = "Hello base class";

  auto objectMapper = oatpp::parser::json::mapping::ObjectMapper::createShared();

  auto json = objectMapper->writeToString(dto);

  std::cout << json->c_str() << std::endl;

}

int main() {

  oatpp::base::Environment::init();
  run();
  oatpp::base::Environment::destroy();

  return 0;
}

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

@oatpp_io_twitter ill try that, probably the initilizing the object went wrong, ill let you know if this works!

oat++

@oatpp_io_twitter

Please also note that you have to extend object as a regular c++ object too:

class HeaderDto : public MyBaseDto /* Should also extend a class here */ {

  DTO_INIT(HeaderDto, MyBaseDto /* mention your base class here */)

  DTO_FIELD(Int64, time);

};

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

Yeah i already had that

oat++

@oatpp_io_twitter

Ok then! Please let me know how it goes.

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

yes this seems to work

thanks alot

oat++

@oatpp_io_twitter

You are welcome, please ping me in case you have more questions

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

I was missing information on this in the documentation, and also examples / test / other code from modules (like the swagger module) does not utilize this in this way. Perhaps this can be added to the docs?

oat++

@oatpp_io_twitter

Sure, good point!

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

just for your info, currently evaluating Oat++ as possible replacement for CPP REST SDK for cross platform (Windows, NVidia Jetson and Xilinx Zync FPGA/ARM core) application

so the help is very much apreciated!

oat++

@oatpp_io_twitter

Cool! Are you planning to use Oat++ simple API or Async?

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

not sure yet, im leaning towards simple api since we are mainly targetting embedded systems where there will be not many concurrent api connections

oat++

@oatpp_io_twitter

That's a good decision - Simple API is more developed and better tested

Benedikt-Alexander Mokroß

@bamkrs

@MJLHThomassen-Sorama I already run oatpp successfully on a simple armv7 Code with 64mb RAM and even an stupid MIPS cpu with 600mhz and 128mb RAM. Both work fine with OpenWRT as OS.

*armv7 core

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

I'm now experimenting with adding headers to my response, is there a better way to do this:
response->putHeader("Custom-Timestamp", oatpp::String(std::to_string(152554).c_str()));

(so not having to create oatpp::String from sting.c_str()

oat++

@oatpp_io_twitter

Hello @MJLHThomassen-Sorama ,

response->putHeader("Custom-Timestamp", "1234");
response->putHeader("Custom-Timestamp", oatpp::utils::conversion::int64ToStr(1234)); // #include "oatpp/core/utils/ConversionUtils.hpp"

MJLHThomassen-Sorama

@MJLHThomassen-Sorama

thanks!

kapilpipaliya

@kapilpipaliya

error: non-constant condition for static assertion when i use arangodb::velocypack::Slice. i think its not copyable.

https://github.com/arangodb/velocypack

oat++

@oatpp_io_twitter

Hello @kapilpipaliya ,

Not sure I understand the question, and how it relates to oatpp.
Please specify.

Thanks

DF-Dave

@DF-Dave

Hello, i have a problem/question with your DTO component of oat++. I try to generate an packet with different types of objects but I can't assign inherited classes. I show you my problem with a little example

...

class Param : public oatpp::data::mapping::type::Object
{
DTO_INIT(Param , Object)
};

class RealParam : public Param
{
DTO_INIT(RealParam, Param)

DTO_FIELD(Int32, magic);

};

class Packet : public oatpp::data::mapping::type::Object
{
DTO_INIT(Packet, Object)

DTO_FIELD(List<Param::ObjectWrapper>::ObjectWrapper, params) 
    = List<Param::ObjectWrapper>::createShared();

};

...

When I try to add an instance (ObjectWrapper) of type RealParam to the list of Packet, I only get an error message from the compiler that there is no known conversion from RealParam::ObjectWrapper to Param::ObjectWrapper. Is there a way to explicitly cast the object or am I still making a mistake somewhere?

oat++

@oatpp_io_twitter

Hello @DF-Dave ,

It is possible to cast ObjectWrapper using oatpp::data::mapping::type::static_wrapper_cast, and it will compile:

class Param : public oatpp::data::mapping::type::Object {

  DTO_INIT(Param , Object);

};

class RealParam : public Param {

  DTO_INIT(RealParam, Param)

  DTO_FIELD(Int32, magic);

};

class Packet : public oatpp::data::mapping::type::Object {

  DTO_INIT(Packet, Object)

  DTO_FIELD(List<Param::ObjectWrapper>::ObjectWrapper, params) = List<Param::ObjectWrapper>::createShared();

};

...

auto packet = Packet::createShared();
auto realParam = RealParam::createShared();
realParam->magic = 10;

Param::ObjectWrapper param = oatpp::data::mapping::type::static_wrapper_cast<Param>(realParam);

packet->params->pushBack(param);

But the output will miss the magic int32 number:

{
  "params": [
    {}
  ]
}

The point here is that you can't serialize things that you won't be able to deserialize

Because if you serialize a child class as a parent, you won't have any info during the deserialization about what child class it was originally

So it is a restriction. And it is an expected behavior here.

So here DTO_FIELD(List<Param::ObjectWrapper>::ObjectWrapper, params) in the Param inside <> brackets is the actual model of the object that should be serialized. Serializer won't know about other fields present in the child.

oat++

@oatpp_io_twitter

Hope I answered your question.
Please let me know if you have more questions.

Regards,
Leonid

DF-Dave

@DF-Dave

Thank you for your answer but I see the problem. But then I have another question can I use templates within the CODEGEN_MACROS so I can put a template at the packet and specify it's list type variable?

oat++

@oatpp_io_twitter

Not sure if I understand correctly...

The point is that the template parameter in the list should define the exact type of the object that you want to serialize.

You can just do like this:

class Param : public oatpp::data::mapping::type::Object {

  DTO_INIT(Param , Object);

};

class RealParam : public Param {

  DTO_INIT(RealParam, Param)

  DTO_FIELD(Int32, magic);

};

class Packet : public oatpp::data::mapping::type::Object {

  DTO_INIT(Packet, Object)

  DTO_FIELD(List<RealParam::ObjectWrapper>::ObjectWrapper, params) = List<RealParam::ObjectWrapper>::createShared();

};

Then, your serializer will serialize all the fields taking into account the base class inheritance.

Or you mean if it's possible to templatize the DTO object?

DF-Dave

@DF-Dave

yeah I mean to templatize the DTO object

oat++

@oatpp_io_twitter

Let me try...

oat++

@oatpp_io_twitter

Ok, I did it, but it looks pretty ugly. I had to introduce a bunch of typedefs:

template<class T>
class Param : public oatpp::data::mapping::type::Object {

  DTO_INIT(Param , Object);

  DTO_FIELD(T, templateParam);

};

template<class T>
class Packet : public oatpp::data::mapping::type::Object {

  DTO_INIT(Packet, Object)

  typedef List<typename Param<T>::ObjectWrapper> ListOfParams;
  typedef typename ListOfParams::ObjectWrapper ListOfParams_ObjectWrapper;

  DTO_FIELD(ListOfParams_ObjectWrapper, params) = ListOfParams::createShared();

};

...

  auto packet = Packet<oatpp::String>::createShared();

  auto param = Param<oatpp::String>::createShared();
  param->templateParam = "Hello";

  packet->params->pushBack(param);

The output:

{
  "params": [
    {
      "templateParam": "Hello"
    }
  ]
}

at least it's possible:)

DF-Dave

@DF-Dave

ok thank you that helped me a lot :)

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