# jsonreader

**Repository Path**: PatchLion/jsonreader

## Basic Information

- **Project Name**: jsonreader
- **Description**: No description available
- **Primary Language**: C++
- **License**: Not specified
- **Default Branch**: master
- **Homepage**: None
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2025-07-06
- **Last Updated**: 2025-07-07

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

# JsonElement C++ JSON 智能类型映射库

## 简介
JsonElement 是一个纯 C++17/14 实现的轻量级 JSON 解析与类型映射工具，基于 jsoncons 库，支持智能类型推断、递归容器、自定义类型、属性宏映射、jsonpath 路径访问等。

- 支持基础类型、std::vector/std::list、std::map<string,T>、自定义业务类型递归转换
- PROPERTY_DEFINE/PROPERTY_DEFINE_WITH_P1 宏支持属性自动映射和路径占位符
- 兼容 MSVC/Clang/GCC，头文件无重复定义和类型萃取冲突
- VSCode 一键构建、调试、断点、example.json 自动拷贝

## 主要文件结构
- jsonelement.h / jsonelement.cpp：核心类型与实现
- examples/example_jsonelement.cpp：用例主程序
- examples/student.h / classes.h：业务类型映射示例
- examples/example.json：测试数据
- CMakeLists.txt / .vscode/：构建与调试配置

## 快速上手
1. 直接 include "jsonelement.h"
2. 通过 `JsonElement root(jsonstr);` 加载 JSON 字符串或文件
3. 使用 `as<T>()` 智能类型推断获取任意类型
4. 用 PROPERTY_DEFINE 宏快速定义属性映射

```cpp
class Student : public JsonElement {
public:
    PROPERTY_DEFINE(std::string, name, "$.name")
    PROPERTY_DEFINE(int, age, "$.age")
};

JsonElement root(jsonstr);
Student stu = root.readByPath("$.students[0]").as<Student>();
std::string name = stu.name();
```

## 复杂类型与容器
- 支持 vector<Student>、list<int>、map<string,Student> 等递归类型
- 支持 jsonpath 路径占位符自动替换

```cpp
class Classes : public JsonElement {
public:
    PROPERTY_DEFINE(std::vector<Student>, students, "$.students[*]")
    PROPERTY_DEFINE_WITH_P1(Student, studentByName, "$.students[?(@.name == \"%1\")]" )
};

Classes cls(jsonstr);
Student s = cls.studentByName("张三");
```

## 兼容性与扩展
- 兼容 C++14/17，避免 void_t/type_traits 重复定义
- 支持自定义异常处理、国际化、自动测试等扩展

## 贡献与许可
- 基于 MIT 协议，欢迎二次开发与贡献
- 依赖 jsoncons（https://github.com/danielaparker/jsoncons）

## 示例数据 example.json

```json
{
  "name": "高三一班",
  "students": [
    {
      "name": "张三",
      "age": 18,
      "score": 95.5,
      "id": "S001"
    },
    {
      "name": "李四",
      "age": 17,
      "score": 88.0,
      "id": "S002"
    },
    {
      "name": "王五",
      "age": 18,
      "score": 91.0,
      "id": "S003"
    }
  ]
}
```

## 完整 main() 示例

```cpp
#include "../jsonelement.h"
#include "classes.h"
#include "student.h"
#include <filesystem>
#include <fstream>
#include <iostream>
#include <string>
#include <vector>

using namespace std;

int main()
{
    // Print current working directory for debug
    std::cout << "Current working directory: " << std::filesystem::current_path().string() << std::endl;

    // Try open example.json in current directory
    std::ifstream fin("example.json");
    if (!fin.is_open()) {
        std::cout << "Failed to open example.json in current directory." << std::endl;
        return 1;
    }
    std::string jsonData((std::istreambuf_iterator<char>(fin)), std::istreambuf_iterator<char>());
    fin.close();

    // 支持两种结构：单个学生 或 班级（含学生数组）
    // 尝试解析为 Classes
    Classes cls(jsonData);
    vector<std::string> studentNames = cls.studentNames();
    if (!studentNames.empty()) {
        for (size_t i = 0; i < studentNames.size(); i++) {
            std::cout << "  Student Name: " << studentNames[i] << std::endl;
        }
    }

    Student studentByName = cls.studentByName("张三");
    if (!studentByName.name().empty()) {
        std::cout << "Student found by name: " << studentByName.name() << std::endl;
    } else {
        std::cout << "No student found with the name 张三." << std::endl;
    }
    vector<Student> students = cls.students();
    if (!students.empty()) {
        std::cout << "Students: " << std::endl;
        for (auto stu : students) {
            std::cout << "  Name: " << stu.name() << ", Age: " << stu.age() << std::endl;
        }
        std::cout << std::endl;
    }
    return 0;
}
```