Confused about iterating through json objects

[danpolanco]

If I have:

{
  "england": {
    "name": "euro",
    "value": 57.99
  },
  "mexico": {
    "name": "peso",
    "value": 31.99
  },
  "us": {
    "name": "USD",
    "value": 42.99
  }
}

And I want to iterate through each, how would I do so?

My attempt so far has been similar to the following:

std::ifstream input_file( const string file_path );
nlohmann::json currencies_json;
currencies_json << input_file;
input_file.close();

unordered_map <string, currency_class> currencies;
for ( const auto currency_json: currencies_json ) {
    currency_class new_currency;

    new_currency[ "country" ] = ???
    new_currency[ "name" ] = ???
    new_currency[ "value"] = ???

    currencies[ country ] = new_currency;
}

I've tried it a a few ways including - for example - creating a string for new_currency[ "country" ] first and then storing it in it like new_currency[ "country" ] = my_string, but I get errors such as:

no member named 'key' in 'nlohmann::basic_json<std::map, std::vector, std::__1::basic_string<char>, bool, long long, double, std::allocator>'

or

[....]:1073:20: error: 'm_it' is a private member of 'nlohmann::basic_json<std::map, std::vector, std::__1::basic_string<char>,
      bool, long long, double, std::allocator>::const_iterator'
           result.m_it.object_iterator = m_value.object->find(key);
                   ^
[...]:89:32: note: in instantiation of member function 'nlohmann::basic_json<std::map, std::vector, std::__1::basic_string<char>, bool, long long, double,
      std::allocator>::find' requested here
                const auto iterator = currencies.find("country");
                                             ^
[...]/build/dependencies/json-prefix/src/json/src/json.hpp:3007:96: note: declared private here
        internal_iterator<typename array_t::const_iterator, typename object_t::const_iterator> m_it;

Could you provide some guidance? I'd really appreciate it!

[danpolanco]

Here is an extended example.

[nlohmann]

Dear @DanTheColoradan

Thanks for reporting. I'll check your issue once I'm back from holidays (next week).

All the best
Niels

[gnzlbg]

Duplicate of #43 . The workaround is basically to (there is a better workaround for clang in the original issue):

#define private public
#include <json.hpp>
#define private private

[nlohmann]

Thanks! I'll fix it as soon as possible.

[gnzlbg]

@nlohmann No rush, we have a workaround. Enjoy the holidays :P

[danpolanco]

Thanks @gnzlbg! And I agree @nlohmann, the workaround is pretty simple so enjoy your vacation :) A new season is upon us.

[gnzlbg]

This issue should have been closed by bb2671d.

[nlohmann]

All iterators have now member functions key() to retrieve the key for objects and value() to retrieve the value. This should fix the mentioned issue.

[danpolanco]

Awesome. Thank you!