Can you tell me what's wrong with my code?

[Curculigo]

#include "glaze/json.hpp"
#include <iostream>
#include <string>

  // Cache configuration
  struct CacheConfiguration {
    int max_cache_anchors;
    int min_total_token;
    bool should_speculate;
  };

  // Model definition
  struct Model {
    std::optional<CacheConfiguration> cache_configuration;
    std::optional<double> default_temperature;
    std::optional<std::string> display_name;
    std::optional<int> max_output_tokens;
    std::optional<int> max_tokens;
    std::string name;
    std::optional<bool> cheapest;
  };

  // Provider definition
  struct Provider {
    std::string api_url;
    std::optional<std::string> display_name;
    std::optional<std::vector<Model>> models;
    std::optional<int> version;
  };

  // Root object
  struct Root {
    glz::generic config;
    std::map<std::string, Provider> providers;
  };

// omitted the main function and the code to load the json file into the string `json`

  Root root{};
  auto foo = glz::read_json(root, json);
  std::cout << foo.custom_error_message << std::endl;
  if (!foo) {
    for (const auto &kv : root.providers) {
      std::cout << "provider: " << kv.first << std::endl;
      std::cout << "api_url: " << kv.second.api_url << std::endl;
      if (kv.second.display_name.has_value()) {
        std::cout << "display_name: " << kv.second.display_name.value()
                  << std::endl;
      }
      if (kv.second.version.has_value()) {
        std::cout << "version: " << kv.second.version.value() << std::endl;
      }
      std::cout << "models:" << std::endl;
      if (kv.second.models.has_value()) {
        for (const auto &it : kv.second.models.value()) {
          std::cout << std::endl;
          if (it.cache_configuration.has_value()) {
            std::cout << "\tcache_configuration:" << std::endl;
            std::cout << "\t\tmax_cache_anchors: "
                      << it.cache_configuration->max_cache_anchors << std::endl;
            std::cout << "\t\tmin_total_token: "
                      << it.cache_configuration->min_total_token << std::endl;
            std::cout << "\t\tshould_speculate: "
                      << it.cache_configuration->should_speculate << std::endl;
          }
          if (it.default_temperature.has_value()) {
            std::cout << "\tdefault_temperature: "
                      << it.default_temperature.value() << std::endl;
          }
          if (it.display_name.has_value()) {
            std::cout << "\tdisplay_name: " << it.display_name.value()
                      << std::endl;
          }
          if (it.max_output_tokens.has_value()) {
            std::cout << "\tmax_output_tokens: " << it.max_output_tokens.value()
                      << std::endl;
          }
          if (it.max_tokens.has_value()) {
            std::cout << "\tmax_tokens: " << it.max_tokens.value() << std::endl;
          }
          std::cout << "\tname: " << it.name << std::endl;
          if (it.cheapest.has_value()) {
            std::cout << "\tcheapest: " << it.cheapest.value() << std::endl;
          }
        }
      }
      std::cout << std::endl;
    }
  }

The json file is attached. I have no idea why it always print nothing. As you can see, I inserted the code to print custom_error_message, but that also printed nothing!
aiassistant.json.txt

[stephenberry]

custom_error_message is typically empty, unless you implement some special custom error handling. Instead, you should have an else on your if (!foo) check and use glz::format_error to nicely format the error:

std::cout<< glz::format_error(foo, json) << std::endl;

You can also use glz::ex::read_json if you would prefer exceptions to be thrown on errors.

If you use either of those approaches you'll get an error back.

[stephenberry]

By default Glaze errors on unknown keys. You can make fields optionals or you can turn off this option using Glaze's compile time options: glz::read<glz::opts{.error_on_unknown_keys = false}>