Sort and limit not working with Mongo + Meteor

This is my publish.js file in which I publish my collection:

const tags = Tags.find({title: {
      $regex: `.*${searchString}.*`,
      $options: 'i'
    }}, {
      sort: { counts: -1 }, limit: 3
    });
    console.log(tags.count());

    return tags;

And this is my components which is subscribing to this collection:

this.tagsSubscription = this.subscribe('tags', () => [this.tag], function (err) {
    that.tags = Tags.find().fetch();
});

So with this I get 2 different errors:

sort and limit are not working: I sometimes get more than 3 results and there are not sorted by 'counts'
the callback is not working properly. It's too fast, I get different result on client and server. I tried with this way, onSuccess() and with Meteor.autorun() but with no luck. If I use a setTimeout I can see the correct cursor

The title search is the only thing that seems working.

Solution

First, according to documentation, .count() will ignore effects of .skip() and .limit(), so, for example, if you have 100 records in total, and your query options has { limit: 3 } then .count() for this cursor will return 100 instead of 3.

Second, looking at your code I assume that your publication expects at least one argument: searchString. But your code that subscribes to it doesn't pass it. I think it should be like that:

Meteor.subscribe('tags', this.tag, () => {
  that.tags = Tags.find().fetch();
});

And lastly, server-side sorting does not affect documents sorting in client-side collections.

For example, let's assume that you have find query as { num: { $gte: 1 } } and there are 3 documents which satisfy this condition, with nums equal 3, 2 and 1 accordingly. These 3 documents will be sent to client collection from this publication.

Now, let's add new document to this mongo collection, with num: 2.5. What will happen, considering you have { limit: 3 } as query options? The publication will send to client: removed event for document with num: 1 and added event for document with num: 2.5. And client-side collection will have documents in that order: 3, 2, 2.5.

Following this, it should be understandable that you should sort your documents on client side as well. So, in my code above it should be:

that.tags = Tags.find({}, { sort: { counts: -1 } }).fetch();

Also, have a look at documentation regarding what happens when publication arguments are changed.