编写有关在node.js的mongodb本机驱动程序中插入文档的问题

Question

I'm having problems using write concerns with mongodb native driver for Node.js. I'm using a single MongoDB server in localhost. This is the code i'm using:

function insertNewDoc(newdoc, cbsuccess, cberror){

db.collection('test').insert(newdoc, {w: 1, wtimeout: 2000}, function(err){
if (err) cberror(err);
else cbsuccess(newdoc);
});

}

I've tried to stop mongodb just before executing this function, but it keeps trying until mongo is on again, and then it inserts the document. What I want is to set a timeout so in case the document had not been successfully inserted after 2 seconds, it returns me an error.

Answer 1

wtimeout is about timeout for waiting for write concern to return, not about the actual connection or insert. Also connections are established before the insert() .

By default node-mongodb-native driver will queue up operations until the database is back again.

If you want to disable this buffer set bufferMaxEntries to 0 .
See here for more information.

See this example code:

// node-mongodb-native_test-connection.js file

var MongoClient = require('mongodb').MongoClient;

// Connect to the db
MongoClient.connect('mongodb://localhost:27017/test', function(err, db) {
  if(err) {
    return console.dir(err);
  }
  console.log(new Date() + ' - We are connected');
  // db.close();
  db.on('close', function () {
    console.log(new Date() + ' - Error...close');
  });

  var collection = db.collection('test');

  setTimeout(function() {
    console.log(new Date() + ' - trying to insert');
    collection.insert({'newdoc': 1}, {w: 1, wtimeout: 2000}, function(err, item){
      if(err) { return console.dir(err); }
      console.log(item);
    });
  }, 2000);
});

Output example:

$ node node-mongodb-native_test-connection.js
Wed Mar 12 2014 17:31:54 GMT+0000 (GMT) - We are connected
Wed Mar 12 2014 17:31:55 GMT+0000 (GMT) - Error...close
Wed Mar 12 2014 17:31:56 GMT+0000 (GMT) - trying to insert
[ { newdoc: 1, _id: 53209a0c939f0500006f6c33 } ]

And see the logs

Wed Mar 12 17:31:55.719 [signalProcessingThread] got signal 2 (Interrupt: 2), will terminate after current cmd ends
Wed Mar 12 17:31:55.719 [signalProcessingThread] now exiting
...
Wed Mar 12 17:31:59.215 [initandlisten] MongoDB starting : pid=67863 port=27017 dbpath=/data/db/ 64-bit host=localhost
...
Wed Mar 12 17:31:59.237 [initandlisten] waiting for connections on port 27017
Wed Mar 12 17:31:59.730 [initandlisten] connection accepted from 127.0.0.1:56730 #1 (1 connection now open)

Change the connection option like so:

MongoClient.connect('mongodb://localhost:27017/test', {
    db: {bufferMaxEntries:0},
  },
  function(err, db) {