java如何避免使用MangGDB C++

Question

我在MongoDB中有一个唯一的索引，以避免重复

我正在尝试将简单代码从java转换为c++ 下面是我将文档插入MongoDB的代码。 代码工作正常，但当我尝试插入相同的文档时，应用程序停止工作

     mongocxx::client conn{ mongocxx::uri{ "mongodb://localhost:27017" } };
     mongocxx::write_concern writeConcern;
     writeConcern.acknowledge_level(mongocxx::write_concern::level(1));

    QFile inputFile(path);
   if (inputFile.open(QIODevice::ReadOnly))
    {
    QTextStream in(&inputFile);
    while (!in.atEnd())
    {
        bsoncxx::builder::stream::document document{};
        auto collection = conn["TestDB"]["fdevices"];
        QString line = in.readLine();
        std::string utf8_text = line.toUtf8().constData();
        document << "Data" << utf8_text;

    collection.insert_one(document.view());
        }
    inputFile.close();
     }

下面是我在java中使用的代码。 在java中，我可以通过使用mongoClient忽略重复项。setWriteConcern（新的WriteConcern（0,10））；然后继续循环到下一个文档

    MongoClient mongoClient = new MongoClient(asList( new ServerAddress(host+":"+port)), 
        singletonList(MongoCredential.createScramSha1Credential(uname.getText(),
        MongoClientOptions.builder().serverSelectionTimeout(2000)
                                                          .build());
        mongoClient.setWriteConcern(new WriteConcern(0, 10));
        DB db = mongoClient.getDB(dblist.getSelectedValue().toString());
        DBCollection bookCollection = db.getCollection(collectionss.getSelectedValue().toString());
        for (int i = 0; i <sixe; i++) {
            server.prolab.setText("Uploaded files: "+i+" Total files: "+sixe);
            BasicDBObject doc = new BasicDBObject("Data",dataList.getModel().getElementAt(i));
            bookCollection.insert(doc);
        }

Answer 1

如果没有正确定义writeConcern方法，请尝试以下代码

mongocxx::client conn{ mongocxx::uri{ "mongodb://localhost:27017" } };

        bsoncxx::builder::stream::document document{};
        mongocxx::write_concern writeConcern;
        writeConcern.acknowledge_level(mongocxx::write_concern::level::k_unacknowledged);
        std::chrono::milliseconds timeout = std::chrono::milliseconds(5000);
        auto collection = conn["TestDB"]["fdevices"];
        collection.write_concern(writeConcern);
        conn.write_concern(writeConcern);

 QFile inputFile(path);
 if (inputFile.open(QIODevice::ReadOnly))
 {
 QTextStream in(&inputFile);
 while (!in.atEnd())
 {
    QString line = in.readLine();
    std::string utf8_text = line.toUtf8().constData();
    document << "Data" << utf8_text;
    collection.insert_one(document.view());
     }
 inputFile.close();
  }