CODEWITHSUNDEEP
c++visual-studio-codenlohmann-json
Tyr
Tyr

Reputation: 610

nlohmann json has no member "exception" error (vscode c++)

I'm trying to build a simple catch structure but I got below error related to nlohmann json library.

error: ‘exception’ in ‘using json = class nlohmann::basic_json<> {aka class nlohmann::basic_json<>}’ does not name a type
     catch (nlohmann::json::exception& e)

here is the code;

#include <iostream>
#include <nlohmann/json.hpp>

    namespace company
    {
        namespace project
        {
            class Serializable
            {
            public:
                virtual void read(const nlohmann::json& json) = 0;
                virtual void write(nlohmann::json& json) const = 0;
    
            bool load(const std::string& fileName)
            {
                try
                {
                    nlohmann::json json;
                    std::ifstream f(fileName.c_str());
                    if (f.good())
                    {
                        f >> json;
                        read(json);
                        return true;
                    }
                }
                catch (nlohmann::json::exception& e)
                {
                    projectError << "Cant read json " << fileName << " Exception: " << e.what();
                }
                projectError << "Cant read json " << fileName;
                return false;
            }

on "exception" there is an explanation as below:

class "nlohmann::basic_json<std::map, std::vector, std::__cxx11::string, bool, int64_t, uint64_t, double, std::allocator, nlohmann::adl_serializer>" has no member "exception"

But I'm pretty sure that there is 'exception' in nlohmann/json.hpp as I checked.

Also there is no issue on nlohmann::json json; part.

What am I doing wrong?

Thanks

Upvotes: 1

Views: 2252

Answers (1)

Mikhail
Mikhail

Reputation: 31

I had the same problem. By default #include <nlohmann/json.hpp> searches for specified file in all system paths. In my case (Ubuntu 18.04) it was /usr/include/nlohmann/json.hpp that has version 2.1.1 and generated the same error about 'nlohmann::json::exception& e'. But I had single_include version in my local directory: ~/projects/json/single_include/nlohmann/json.hpp that had version 3.9.1 without that error.

So, just change your include statement to use right version:

#include "your_src_dir/single_include/nlohmann/json.hpp"

Alternatively, specify include paths with the g++ -I flag.

Upvotes: 1

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