NodeJS + MongoDB - find().sort().toArray() does not work

Question

I have a collection "logs" and I need to sort it by most recent first. With findOne() I do:

.sort($natural: -1)

However this is not doing anything now.

  db('logs').find({'userId': userId}).sort({ $natural: -1}).toArray(function (err, result) {
    if (err) console.error(err)
    if (result.length > 0) {
      console.log('Found ' + result.length + ' log entries', result)
      if (callback) callback(result)
    } else {
      console.log('No log entries for ' + userId, userId)
      if (callback) callback(null)
    }
  })

This outputs the same as $natural: 1. Or if I skip sort() all together.

Collection:

{_id: "5c044d13f4c6db53a047fe37", dateTime: "2018-12-02 22:22", userId: 5, event: "Failed to update Media Package sale", info: {userId: 5, AmountOfPrePaidItems: 1}}
{_id: "5c044d2bf4c6db53a047fe38", dateTime: "2018-12-02 22:22", userId: 5, event: "Failed to update Media Package sale", info: {userId: 5, AmountOfPrePaidItems: 0}}
{_id: "5c044d56f4c6db53a047fe39", dateTime: "2018-12-02 22:23", userId: 5, event: "Failed to update Media Package sale", info: {userId: 5, AmountOfPrePaidItems: 1}}

Using Atlas mongoDB 4.0.4

Edit 1: .sort( _id: -1) also gives same output order

If your sorting was working before, I'd say it's pretty likely that you're accidentally reordering your results outside of the code you're showing. — JohnnyHK
– JohnnyHK, Commented Dec 3, 2018 at 2:28

Akrion · Accepted Answer · 2018-12-02 23:28:50Z

6

For what you are trying to do you should simply use:

db('logs').find({'userId': userId}).sort({ _id: -1 })

if you want to get the most recent first since _id contains the date etc.

As far as $natural goes:

The $natural parameter returns items according to their natural order within the database. This ordering is an internal implementation feature, and you should not rely on any particular structure within it.

Using your sample data:

db.getCollection('items').find().sort({ _id: -1})

You get:

/* 1 */
{
    "_id" : "5c044d56f4c6db53a047fe39",
    "dateTime" : "2018-12-02 22:23",
    "userId" : 5,
    "event" : "Failed to update Media Package sale",
    "info" : {
        "userId" : 5,
        "AmountOfPrePaidItems" : 1
    }
}

/* 2 */
{
    "_id" : "5c044d2bf4c6db53a047fe38",
    "dateTime" : "2018-12-02 22:22",
    "userId" : 5,
    "event" : "Failed to update Media Package sale",
    "info" : {
        "userId" : 5,
        "AmountOfPrePaidItems" : 0
    }
}

/* 3 */
{
    "_id" : "5c044d13f4c6db53a047fe37",
    "dateTime" : "2018-12-02 22:22",
    "userId" : 5,
    "event" : "Failed to update Media Package sale",
    "info" : {
        "userId" : 5,
        "AmountOfPrePaidItems" : 1
    }
}

Notice that top document is:

"_id" : "5c044d56f4c6db53a047fe39",
"dateTime" : "2018-12-02 22:23",

Doing:

db.getCollection('items').find().sort({ _id: 1})

Notice that:

"_id" : "5c044d13f4c6db53a047fe37",
"dateTime" : "2018-12-02 22:22",

Is the top document.

edited Dec 2, 2018 at 23:28

answered Dec 2, 2018 at 22:56

Akrion

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5 Comments

Rune Aspvik Over a year ago

Hi @akrion! I have tried this too. But I get the output in the same order. I am thinking it has something to do with toArray()

Akrion Over a year ago

Interesting since I used your data and got different result. See updated answer.

Rune Aspvik Over a year ago

In the mongo shell I get the same result as you, it works. But my case is in a NodeJS environment, and using .toArray()

Akrion Over a year ago

@RuneAspvik I get exactly the same results in nodeJS with this: db.collection('items').find({}).sort({ _id: -1}).toArray((err, res) => ... where items is the exact collection you posted.

Rune Aspvik Over a year ago

My initial solution worked, so did yours. I had a replica route in my server that caught the request before the one I was working on.

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