JS中的MongoDB ObjectID

Question

I am trying to make pagination work with MongoDB without skip();

In mongo shell I got the following results with my query, but in Javascript a empty [];

I think I am doing the ObjectID wrong, I use the "mongodb ObjectID" and "mongojs" libs with Node.js.

Mongo shell:

db.chat.find({
  _id: { $lt: ObjectId("53e901c125c68270311e5f41") },
  user_id: 1,
  target_user_id: 1,
  "$or": [{user_id: 1, target_user_id:1}]
}).sort({
  ts: -1
}).limit(5);

Output:

{ "_id" : ObjectId("53e88e1bb76e781413000029"), "user_id" : 1, "target_user_id" : 1, "message" : "Hey" }
{ "_id" : ObjectId("53e88f51b76e78141300002a"), "user_id" : 1, "target_user_id" : 1, "message" : "Hey" }
//ect.

Javascript

var ObjectID            = require('mongodb').ObjectID;
var db                  = require("mongojs").connect(db_uri, db_collections);

//last_ts = "53e901c125c68270311e5f41"
var last_id = ObjectID.createFromHexString(last_ts);

db.chat.find({
  _id: { $lt: last_id },
  user_id: 1,
  target_user_id: 1,
  "$or": [{user_id: 1, target_user_id:1}]
}).sort({
  ts: -1
}).limit(5).toArray(function (err, docs) {
  console.log("docs:"+docs); //"docs" - no result
  console.log("err:"+err); //"err:null"

  if(docs != null){
    console.log(JSON.stringify(docs)); //"docs:[]"
  }
});

How can I get the same result, with my query in JS?

Edit with $oid from the docs:

http://docs.mongodb.org/manual/reference/mongodb-extended-json/#oid

Still not working..

var last_ts = "53e901c125c68270311e5f41";
db.chat.find({_id: {$lt: {"$oid": last_ts}}, user_id:1, target_user_id:1, "$or": [{user_id: 1, target_user_id:1}]}).sort({ts: -1}).limit(5)

Edit Now working with simply as:

var last_ts = "53e901c125c68270311e5f41";
new ObjectID(last_ts)

Answer 1

If I'm not mistaken, you can simply pass the ObjectID string to the mongo query:

db.chat.find({
    _id: { $lt: last_ts},
    user_id: 1,
    target_user_id: 1,
    "$or": [{user_id: 1, target_user_id:1}]
})
...