Mongo db Collection find returns from the first entry not from last from client side

Question

I am using mongodb and i am querying the database with some conditions which are working fine but the results are coming from the first entry to last where as i want to query from the last added entry to the collection in database

TaggedMessages.find({taggedList:{$elemMatch:{tagName:tagObj.tagValue}}}).fetch()

Does this answer your question? [How to get the last N records in mongodb?](https://stackoverflow.com/questions/4421207/how-to-get-the-last-n-records-in-mongodb) — Tim Biegeleisen, Nov 28 '20 at 06:22

Jankapunkt · Accepted Answer · 2020-11-28T11:01:40.947

2

Meteor uses a custom wrapped version of Mongo.Collection and Mongo.Cursor in order to support reactivity out of the box. It also abstracts the Mongo query API to make it easier to work with.

This is why the native way of accessing elements from the end is not working here.

On the server

In order to use $natural correctly with Meteor you can to use the hint property as option (see the last property in the documentation) on the server:

const selector = {
  taggedList:{ $elemMatch:{ tagName:tagObj.tagValue } }
}

const options = {
  hint: { $natural : -1 }
}

TaggedMessages.find(selector, options).fetch()

Sidenote: If you ever need to access the "native" Mongo driver, you need to use rawCollection

On the client

On the client you have no real access to the Mongo Driver but to a seemingly similar API (called the minimongo package). There you won't have $natural available (maybe in the future), so you need to use sort with a descenging order:

const selector = {
  taggedList:{ $elemMatch:{ tagName:tagObj.tagValue } }
}

const options = {
  sort: { createdAt: -1 }
}

TaggedMessages.find(selector, options).fetch()

edited Nov 28 '20 at 11:01

answered Nov 28 '20 at 07:26

Jankapunkt

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its still querying from the first to end, not end to first – Wahdat Jan Nov 28 '20 at 07:43
Maybe it's interfered by `$elemMatch` or you use any addittional `sort` here? Does it work if you just use the all selector `{}`? – Jankapunkt Nov 28 '20 at 08:27
Note, that it's server-only, as mentioned in the docs. – Jankapunkt Nov 28 '20 at 08:28
but sort is for both i think but that is still not working – Wahdat Jan Nov 28 '20 at 08:30
const selector = { taggedList:{ $elemMatch:{ tagName:tagObj.tagValue } } } const options = { sort: { createdAt : 1 } } – Wahdat Jan Nov 28 '20 at 08:31
it is still sorting the way it was not from the reverse – Wahdat Jan Nov 28 '20 at 08:31
1

This is because `createdAt: 1` is sorting ascending. If you want to sort descending you need `createdAt: -1` – Jankapunkt Nov 28 '20 at 10:58
and still hint and natural is working in server side but i need to make query from client side , so i updated ur answer – Wahdat Jan Nov 28 '20 at 11:02
1

hahah, did u add the same thing, sort? i too did that – Wahdat Jan Nov 28 '20 at 11:04

Mongo db Collection find returns from the first entry not from last from client side

1 Answers1

On the server

On the client