Question

我想将以下shell脚本（MongoDB shell版本：2.6.1）翻译成C ++语言

db.account.aggregate([{$group: { _id:null, totalAmount: { $sum: "$amount" },count: { $sum: 1 }}}])

我尝试了以下代码：

     void test1(mongo::DBClientConnection& c)
     {
       BSONObj res;

       BSONArray pipeline = BSON_ARRAY( 
                    BSON( "$group" << 
                         BSON( "_id" << "null" ) << 
                         BSON( "totalAmount" << BSON( "$sum" << "$amount" ))<<
                         BSON( "count" << BSON( "$sum" << 1 ))
                        )
                  );

       c.runCommand("test",BSON("aggregate" << "account" << "pipeline" << pipeline ),res);

       cout << res.toString() << endl;
     }

上面的代码会导致编译错误！

     void test2(mongo::DBClientConnection& c)
     {
       BSONObj res;

       vector<BSONObj> pipeline;   
       pipeline.push_back( BSON( "$group" << BSON( "_id" << "null" ) ) );
       pipeline.push_back( BSON( "totalAmount" <<  BSON( "$sum" <<  "$amount" )) );

       c.runCommand( "test", BSON( "aggregate" << "account" << "pipeline" << pipeline ), res);

       cout << collection1<<res.toString() << endl;
     }

以上代码会导致运行时错误！

任何人都可以帮助我吗？谢谢！

Answer 1

乌姆鲁.. 当我被执行时，此代码正在成功运行。我有一个证明拍摄，但“Stack overflow Answer”不允许我上传图片。:(

我猜这是轻微的语法错误。您的金额是否添加到组内？检查你的代码。

以下是我的测试代码：

[代码]

DBClientConnection c;
BSONObj res;

vector<BSONObj> pipeline;   
c.connect("127.0.0.1:27017");
pipeline.push_back( BSON( "$group" << BSON( "_id" << "null" << "totalAmount" <<  BSON( "$sum" <<  "$amount" ))));

c.runCommand( "security", BSON( "aggregate" << "nac" << "pipeline" << pipeline ), res);

cout << "Succeed!!!" << endl;
cout << "collection1: " << res.jsonString() << endl;

return 0;

[执行]

〜/ bin] $ ./test.exe

成功!!!

collection1：{result：[{_ id：“null”，totalAmount：426}]，ok：1.0}

〜/二进制] $

Answer 2

我不擅长英语，但我可以帮助你。

1）

void test1(mongo::DBClientConnection& c)
 {
   BSONObj res;

   BSONArray pipeline = BSON_ARRAY( 
                BSONArray pipeline = BSON_ARRAY( 
                BSON( "$group" << 
                     BSON( "_id" << "null" << "totalAmount" << BSON( "$sum" << "$amount" ))<< "count" << BSON( "$sum" << 1 )
                    )
              );

   c.runCommand("test",BSON("aggregate" << "account" << "pipeline" << pipeline ),res);

   cout << res.toString() << endl;
 }

2）

void test2(mongo::DBClientConnection& c)
 {
   BSONObj res;

   vector<BSONObj> pipeline;   
   pipeline.push_back( BSON( "$group" << BSON( "_id" << "null" << "totalAmount" <<  BSON( "$sum" <<  "$amount" ))));

   c.runCommand( "test", BSON( "aggregate" << "account" << "pipeline" << pipeline ), res);

   cout << collection1<<res.toString() << endl;
 }

MongoDb sum聚合C ++

2 个答案: