C++调用MongoDB数据库(一)

一、简介

本篇文章主要讲述如何使用C++调用MongoDB数据库实现增、删、查、改。

MongoDB

MongoDB是一个基于分布式文件存储的数据库，由C++语言编写，一般多用于WEB应用进行可扩展的高性能数据存储。MongoDB是一个介于关系数据库和非关系数据库之间的产品，是非关系数据库当中功能最丰富，最像关系数据库的。它支持的数据结构非常松散，是类似json的bson格式，因此可以存储比较复杂的数据类型。

MongoDB文档

MongoDB中的记录是一个文档，它是由字段和值对组成的数据结构。
多个键及其关联的值有序地放在一起就构成了文档。
MongoDB文档类似于JSON对象。字段的值可以包括其他文档，数组和文档数组。

{
	name: "xm",
	password: "123456",
}

MongoDB集合

MongoDB的集合就类似数据的表，数据库中的每行数据就是一个文档，及集合是一组文档的集合。

二、连接工具

C++本身并没有提供方法向连接MongoDB，但好在网上有C++连接MongoDB驱动(mongodb-c-driver ,mongo-cxx-driver)，只是需要自行编译这些库的运行需要依赖boost库(对应编译方法及编译好的库，若有时间后面我会写文章介绍并给出编译好的库)

三、代码

这是通过工具进行MogoDB连接及增删查改的一些代码

#ifndef MONGODB_TOOL_OBJ_H
#define MONGODB_TOOL_OBJ_H

#include <bsoncxx/builder/stream/document.hpp>
#include <bsoncxx/types.hpp>
#include <mongocxx/client.hpp>
#include <mongocxx/instance.hpp>
#include <mongocxx/uri.hpp>
#include <bsoncxx/json.hpp>
#include <QString>
#include <QVariantMap>

using bsoncxx::builder::stream::document;
using bsoncxx::builder::stream::open_document;
using bsoncxx::builder::stream::close_document;
using bsoncxx::builder::stream::open_array;
using bsoncxx::builder::stream::close_array;
using bsoncxx::builder::stream::finalize;
using namespace mongocxx;
using namespace mongocxx::options;
using bsoncxx::builder::basic::kvp;
using bsoncxx::builder::basic::make_document;
using bsoncxx::to_json;

class MongoDBToolObj
{
protected:
	mongocxx::instance* m_dbInstance = nullptr;
	mongocxx::client* m_client = nullptr;

	QString m_hostName;
	QString m_port;

public:
	stdx::optional<bsoncxx::document::value> find_One(QString db, QString coll, document& filter, const mongocxx::v_noabi::options::find& options = mongocxx::v_noabi::options::find());
	cursor* find(QString db, QString coll, document& filter, const mongocxx::v_noabi::options::find& options = mongocxx::v_noabi::options::find());
	stdx::optional<result::insert_one> insert_One(QString db, QString coll, document& doc, const mongocxx::v_noabi::options::insert& options = {});
	stdx::optional<result::update> update_One(QString db, QString coll, document& filter, document& value, const mongocxx::v_noabi::options::update& options = mongocxx::v_noabi::options::update());
	stdx::optional<result::update> update_Many(QString db, QString coll, document& filter, document& value, const mongocxx::v_noabi::options::update& options = mongocxx::v_noabi::options::update());
	stdx::optional<result::delete_result> delete_One(QString db, QString coll, document& filter, const mongocxx::v_noabi::options::delete_options& options = mongocxx::v_noabi::options::delete_options());
	stdx::optional<result::delete_result> delete_Many(QString db, QString coll, document& filter, const mongocxx::v_noabi::options::delete_options& options = mongocxx::v_noabi::options::delete_options());
	std::int64_t countDocument(QString db, QString coll, document& filter, const options::count& option = options::count());

public:
	MongoDBToolObj();
	MongoDBToolObj(QString hostName, QString port);
	void setHostName(QString hostName);
	void setPort(QString port);
	bool connectToHost();
	mongocxx::client* client();
	~MongoDBToolObj();

public:
	stdx::optional<bsoncxx::builder::stream::document> mapToDocument(QMap<QString, QString> map);
};

#endif // MONGODB_TOOL_OBJ_H

#include "MongoDBToolObj.h"

MongoDBToolObj::MongoDBToolObj()
{
}

MongoDBToolObj::MongoDBToolObj(QString hostName, QString port)
{
	m_hostName = hostName;
	m_port = port;
}

void MongoDBToolObj::setHostName(QString hostName)
{
	m_hostName = hostName;
}

void MongoDBToolObj::setPort(QString port)
{
	m_port = port;
}

bool MongoDBToolObj::connectToHost()
{
	if ((m_hostName != "") && (m_port != ""))
	{
		if (m_dbInstance)
		{
			delete m_dbInstance;
			m_dbInstance = nullptr;
		}

		if (m_client)
		{
			delete m_client;
			m_client = nullptr;
		}

		m_dbInstance = new(std::nothrow) mongocxx::instance();
		m_client = new(std::nothrow) mongocxx::client(mongocxx::uri{ ("mongodb://" + m_hostName + ":" + m_port).toStdString().c_str() });
	
		if (!m_client)
		{
			return false;
		}
		else
		{
			return true;
		}
	}
	else
	{
		return false;
	}
}

mongocxx::client* MongoDBToolObj::client()
{
	return m_client;
}

stdx::optional<bsoncxx::document::value> MongoDBToolObj::find_One(QString db, QString coll, document& filter, const mongocxx::v_noabi::options::find& options)
{
	stdx::optional<bsoncxx::document::value> ret;

	if (m_dbInstance && m_client)
	{
		return (*m_client)[db.toStdString().c_str()][coll.toStdString().c_str()].find_one(filter.view(), options);
	}

	return ret;
}

cursor* MongoDBToolObj::find(QString db, QString coll, document& filter, const mongocxx::v_noabi::options::find& options)
{
	if (m_dbInstance && m_client)
	{
		auto c = (*m_client)[db.toStdString().c_str()][coll.toStdString().c_str()].find(filter.view(), options);
		return new(std::nothrow) cursor(std::move(c));
	}

	return nullptr;
}

stdx::optional<result::insert_one> MongoDBToolObj::insert_One(QString db, QString coll, document& doc, const mongocxx::v_noabi::options::insert& options)
{
	stdx::optional<result::insert_one> ret;

	if (m_dbInstance && m_client)
	{
		ret = (*m_client)[db.toStdString().c_str()][coll.toStdString().c_str()].insert_one(doc.view(), options);
	}

	return ret;
}

stdx::optional<result::update> MongoDBToolObj::update_One(QString db, QString coll, document& filter, document& value, const mongocxx::v_noabi::options::update& options)
{
	stdx::optional<result::update> ret;
	if (m_dbInstance && m_client)
	{
		ret = (*m_client)[db.toStdString().c_str()][coll.toStdString().c_str()].update_one(
			filter.view(),
			make_document(kvp("$set", value)),
			options
		);
	}

	return ret;
}

stdx::optional<result::update> MongoDBToolObj::update_Many(QString db, QString coll, document& filter, document& value, const mongocxx::v_noabi::options::update& options)
{
	stdx::optional<result::update> ret;
	if (m_dbInstance && m_client)
	{
		ret = (*m_client)[db.toStdString().c_str()][coll.toStdString().c_str()].update_many(
			filter.view(),
			make_document(kvp("$set", value)),
			options
		);
	}

	return ret;
}

stdx::optional<result::delete_result> MongoDBToolObj::delete_One(QString db, QString coll, document& filter, const mongocxx::v_noabi::options::delete_options&  options)
{
	stdx::optional<result::delete_result> ret;

	if (m_dbInstance && m_client)
	{
		ret = (*m_client)[db.toStdString().c_str()][coll.toStdString().c_str()].delete_one(filter.view(), options);
	}

	return ret;
}

stdx::optional<result::delete_result> MongoDBToolObj::delete_Many(QString db, QString coll, document& filter, const mongocxx::v_noabi::options::delete_options& options)
{
	stdx::optional<result::delete_result> ret;

	if (m_dbInstance && m_client)
	{
		ret = (*m_client)[db.toStdString().c_str()][coll.toStdString().c_str()].delete_many(filter.view(), options);
	}

	return ret;
}

std::int64_t MongoDBToolObj::countDocument(QString db, QString coll, document& filter, const options::count& option)
{
	return (*m_client)[db.toStdString().c_str()][coll.toStdString().c_str()].count_documents(filter.view(), option);
}

MongoDBToolObj::~MongoDBToolObj()
{
	delete m_dbInstance;
	delete m_client;
}

stdx::optional<bsoncxx::builder::stream::document> MongoDBToolObj::mapToDocument(QMap<QString,QString> map)
{
	bsoncxx::builder::stream::document doc;
	QMap<QString,QString>::iterator iter = map.begin();
	while (iter != map.end())
	{
// 		qDebug() << "Iterator " << iter.key() << ":" << iter.value(); // 迭代器
		doc << iter.key().toStdString()
			<< iter.value().toStdString();
		iter++;
	}

	return doc;
}