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ATL with COM Native C++ JSON (de)serializer

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12 Mar 2017CPOL 19K   227   5   1
Deserialization and serialization classes for JSON objects in native C++ with COM and ATL

Introduction

Microsoft provides JSON parsing capability in .NET but those wishing to do ATL Server programming will have to roll their own. These classes address that issue.  They solve the generic types of JavaScript using COM objects including VARIANT and SAFEARRAY.

Background

One should be familiar with ATL, COM, C++, JSON and server-side programming.

Using the Code

Deserialization example (assuming in a CRequestHandlerT<> derived class):

C++
_tavariant_t varDeserialized;
CAtlMap<CStringW, VARIANT, CStringElementTraitsI<CStringW>>* dictionary;
JavaScriptObjectDeserializer::BasicDeserialize(varDeserialized, 
((CStringA)m_HttpRequest.FormVars.GetKeyAt(pos)).GetBuffer(), c_DefaultRecursionLimit);
if (varDeserialized.vt == (VT_BYREF | VT_UNKNOWN)) {
    dictionary = &((_tavariant_t::DictionaryVariant*)V_BYREF(&varDeserialized))->Dictionary;
}

Serialization example (assuming in a CRequestHandlerT<> derived class):

C++
_tavariant_t varDeserialized;
CAtlArray<CStringW> varArray;
if (AtlArrayToVariant<CStringW>(varDeserialized, varArray) {
    m_HttpResponse << JavaScriptSerializer::SerializeInternal(varDeserialized);
}

Points of Interest

This is based off older .NET 2.0 JSON serialization code and could be updated with any improvements since then. Reflector and decompilation of the .NET libraries allowed for a decent translation though many of the native .NET objects had to use C++ equivalents and the translation is quite large given the nature of C++ is quite different.

History

  • Initial version

License

This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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Comments and Discussions

 
GeneralNot too much Pin
Marius Bancila12-Mar-17 12:25
professionalMarius Bancila12-Mar-17 12:25 

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