Inserting array of arrays into mongo with c++

Question

The following code works, what it does is: it reads from a buffer and appends to the "s" field in Mongo, but makes a call to the database every time I go through the loop:

bsonData = BSON("$push"<<BSON("s" << BSON("r" << (unsigned int)RecordNumber << "t" << Variant << "u" << TimeStamp << "v" << Value)));

What I would like to do is fill a vector with the 4 values, and insert that vector into the database in one call, I tried this:

for(i=0;i<vRecNo.size();i++)
{
    bOB.append("s", BSON("r" << (unsigned int)vRecNo[i] << 
                            "t" << (unsigned int)vType[i] << 
                            "u" << (unsigned int)vTimeStamp[i] << 
                            "v" << (unsigned int)vValue[i]));
}

but creates duplicate "s" field in Mongo. Any help is greatly appreciated, thank you in advance.

Sid · Accepted Answer · 2012-09-17 18:41:15Z

I am not entirely clear as to what you are asking but judging from the title I will try to offer help.

There are two ways to create BSON arrays in mongo with C++ :

Use BSON_ARRAY macro like BSON macro, but without keys. Eg.

BSONArray arr = BSON_ARRAY( "hello" << 1 << 2 << BSON( "foo" << BSON_ARRAY( "bar" << "baz" << "qux" ) ) );

The above example will create an array with four values, where the last element is a BSON document with 3 array values

[ "hello", 1, 2, { foo : ["bar", "baz", "qux"] } ]
Use BSONArrayBuilder to build arrays without the macro. Eg.

BSONArrayBuilder b; BSONArray arr = b.append(1).append(2).arr();

This will create an array with 2 values [ 1, 2 ]

So in your cause, if you want to create a vector with 4 values, you should create an array, using one of the methods described above, assign that array to "s" and then insert the resulting document. That will give you something of this form { s : [ value1, value2, value3, value4 ] }

Mick . · Accepted Answer · 2012-09-18 17:25:14Z

2

Thank you for the hint, I finally figured it out and I'm posting the piece of code that worked for me:

   BSONObjBuilder bOb;
   BSONArrayBuilder bArr;
   for(i=0;i<vRecNo.size();i++)
    {
      BSONObj bo = BSON("r" << (unsigned int)vRecNo[i] << "t" << vType[i] << "u" << (unsigned int)vTimeStamp[i] << "v" << vValue[i]);
      bArr.append(bo);
    }
  bOb.append("s", bArr.arr());
  BSONObj bsonData = BSON("$set" << bOb.obj());

  conn.update("DatabaseName.Collection", qryData, bsonData);

answered Sep 18, 2012 at 17:25

Mick .

711 silver badge3 bronze badges

Comments

Iulian Rotaru · Accepted Answer · 2015-10-19 12:16:41Z

0

You could convert the vector into std::list and append the list:

std::list<std::string> aList(aVec.begin(),avec.end())
BSONArrayBuilder arrBuilder;
arrBuilder.append(aList);

It is strange that you can append a std::list but not a std::vec.

answered Oct 19, 2015 at 12:16

Iulian Rotaru

722 bronze badges

Collectives™ on Stack Overflow

Inserting array of arrays into mongo with c++

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related