Mongodb C++正则表达式查询

Question

如何在C++中使用正则表达式查询MongoDB数据库。

Mongo-CXX-Driver-R3.1.1

包括听力

#include <cstdlib>
#include <iostream>
#include <bsoncxx/builder/stream/document.hpp>
#include <bsoncxx/json.hpp>
#include <mongocxx/client.hpp>
#include <mongocxx/instance.hpp>
#include <mongocxx/uri.hpp>
#include <cstdint>
#include <vector>
#include <mongocxx/stdx.hpp>
#include <bson.h>
#include <conio.h> 
#include <sstream> 
#include <stdio.h> 
#include <string>
#include <bsoncxx/types.hpp>
#include <mongocxx/exception/exception.hpp>
#include <bsoncxx/builder/basic/document.hpp>
#include <bsoncxx/builder/basic/kvp.hpp>

using bsoncxx::builder::stream::close_document;
using bsoncxx::builder::stream::document;
using bsoncxx::builder::stream::finalize;
using bsoncxx::builder::stream::open_document;
using bsoncxx::builder::basic::kvp;
using bsoncxx::builder::basic::make_document;

这是我尝试过的。

  void MyClass::on_querybtn_clicked()
   {

auto collection = conn["TestDB"]["fdevices"];
bsoncxx::types::b_regex::b_regex();//i am lost here dont know how to use it
auto cursor = collection.find({});

 for (auto doc : cursor) {

QString qstr = QString::fromStdString(bsoncxx::to_json(doc));
QJsonDocument docum = QJsonDocument::fromJson(qstr.toUtf8());
QJsonObject object = docum.object();
QString call = object["Data"].toString();
ui.mqttList->addItem(call);
}
}

以前我用Java构建了一个软件，现在我正在尝试用Qt C++构建同样的软件，我是C++的新手。

下面是我在java中用于查询的查询代码。

 DBObject query = new BasicDBObject();
 Pattern regex = Pattern.compile("^14-09-2017"); 
 query.put("Data", regex);

Answer 1

使用一些生成器并制作文档，为模式提供字符串输入：

#include <bsoncxx/builder/basic/document.hpp>
#include <bsoncxx/builder/basic/kvp.hpp>

using bsoncxx::builder::basic::kvp;
using bsoncxx::builder::basic::make_document;

auto cursor = collection.find(make_document(
  kvp("Data", bsoncxx::types::b_regex{"^14-09-2017"})
));

比stream builder IMHO更容易阅读，但基本前提是存在的。仍然是用于输入的字符串，很像pattern.compile()