Save inventory data used UserDefault

[antn9x]

How to save JSON object in UserDefault, I have plan to save inventory data but don't know how to implement. Any suggest?

[rh101]

What do you mean by JSON object? If it's something like an object that contains a structure (rapidjson::Document etc.), then there should be a method to output the JSON as a string, which you can then save to UserDefault. Then when you read it back, recreate the object from that saved JSON string.

[antn9x]

Can we store in Binary object? JSON object like { itemId: 1, quantity: 2 }

[AlexandreK38]

In binary I don't think so but you can save a json object to string (basically serialize it) and save this string into UserDefault, and read it to json back when retrieving it.
You can create json using rapidjson and then serialize it with

rapidjson::Document document = ... rapidjson::StringBuffer buffer; rapidjson::Writer<rapidjson::StringBuffer> writer(buffer); document.Accept(writer); std::string str = std::string(buffer.GetString()); // use GetString() as you want 

[paulocoutinhox]

Hi,

Generally we have a GameData class that we convert it to JSON with RapidJSON and save to some place, locally, remote, UserDefault, etc and method that save/load it to/from JSON.

Sample code:

// GameData.h #pragma once // keep includes minimal and portable #include <string> #include <vector> #include <unordered_map> #include <fstream> #include <sstream> // rapidjson #include <rapidjson/document.h> #include <rapidjson/writer.h> #include <rapidjson/prettywriter.h> #include <rapidjson/stringbuffer.h> // axmol #include "base/UserDefault.h" #include "platform/FileUtils.h" namespace ax { class GameData { public: // basic game state int coins = 0; int level = 1; // simple collections std::unordered_map<std::string, int> inventory; // e.g. {"potion": 3, "key": 1} std::vector<int> completedLevels; // e.g. [1,2,3] // serialize current state to a compact json string std::string toJsonString(bool pretty = false) const { // build a rapidjson object rapidjson::Document doc; doc.SetObject(); auto& alloc = doc.GetAllocator(); // primitives doc.AddMember("coins", coins, alloc); doc.AddMember("level", level, alloc); // inventory as object rapidjson::Value inv(rapidjson::kObjectType); for (const auto& kv : inventory) { rapidjson::Value k; k.SetString(kv.first.c_str(), static_cast<rapidjson::SizeType>(kv.first.size()), alloc); inv.AddMember(k, kv.second, alloc); } doc.AddMember("inventory", inv, alloc); // completed levels as array rapidjson::Value comp(rapidjson::kArrayType); for (int lv : completedLevels) { comp.PushBack(lv, alloc); } doc.AddMember("completedLevels", comp, alloc); // write to string rapidjson::StringBuffer buffer; if (pretty) { rapidjson::PrettyWriter<rapidjson::StringBuffer> writer(buffer); writer.SetIndent(' ', 2); doc.Accept(writer); } else { rapidjson::Writer<rapidjson::StringBuffer> writer(buffer); doc.Accept(writer); } return buffer.GetString(); } // load state from a json string bool fromJsonString(const std::string& json) { rapidjson::Document doc; if (doc.Parse(json.c_str()).HasParseError() || !doc.IsObject()) { return false; } // read primitives if present if (doc.HasMember("coins") && doc["coins"].IsInt()) coins = doc["coins"].GetInt(); if (doc.HasMember("level") && doc["level"].IsInt()) level = doc["level"].GetInt(); // read inventory inventory.clear(); if (doc.HasMember("inventory") && doc["inventory"].IsObject()) { for (auto it = doc["inventory"].MemberBegin(); it != doc["inventory"].MemberEnd(); ++it) { if (it->value.IsInt()) { inventory[it->name.GetString()] = it->value.GetInt(); } } } // read completed levels completedLevels.clear(); if (doc.HasMember("completedLevels") && doc["completedLevels"].IsArray()) { for (auto& v : doc["completedLevels"].GetArray()) { if (v.IsInt()) completedLevels.push_back(v.GetInt()); } } return true; } // save to axmol user defaults (persistent key-value store) bool saveToUserDefault(const std::string& key, bool pretty = false) const { const auto json = toJsonString(pretty); UserDefault::getInstance()->setStringForKey(key.c_str(), json); UserDefault::getInstance()->flush(); return true; } // load from axmol user defaults bool loadFromUserDefault(const std::string& key) { const auto json = UserDefault::getInstance()->getStringForKey(key.c_str(), ""); if (json.empty()) return false; return fromJsonString(json); } // save to a file in writable path bool saveToFile(const std::string& relativePath, bool pretty = false) const { const auto full = FileUtils::getInstance()->getWritablePath() + relativePath; std::ofstream ofs(full, std::ios::binary); if (!ofs.is_open()) return false; const auto json = toJsonString(pretty); ofs.write(json.data(), static_cast<std::streamsize>(json.size())); return ofs.good(); } // load from a file in writable path bool loadFromFile(const std::string& relativePath) { const auto full = FileUtils::getInstance()->getWritablePath() + relativePath; std::ifstream ifs(full, std::ios::binary); if (!ifs.is_open()) return false; std::stringstream ss; ss << ifs.rdbuf(); return fromJsonString(ss.str()); } // convenient reset void resetDefaults() { coins = 0; level = 1; inventory.clear(); completedLevels.clear(); } }; } // namespace ax