So i've implemented infiniscroll with mongoose and my query looks like this
const posts = await Seed.find({status: 'APPROVED', 'color.name': color})
.skip(parseInt(skip) || 0)
.limit(8)
.exec()
That works great, from 0 to the end of posts. However if i add .sort({upvotes: -1})
const posts = await Seed.find({status: 'APPROVED', 'color.name': color})
.sort({upvotes: -1})
.skip(parseInt(skip) || 0)
.limit(8)
.exec()
Everything goes nuts, i can get the same post 6 times.
I've stared at this for hours now and i simply cannot understand why this is happening and it feels like a bug.
I've tried .sort('-upvotes'), .sort({upvotes: 'desc'}), .sort({'upvotes': 'desc'})
Update: Sorting by .sort('-date') actually works, so i'm having a problem with upvotes specifically. The majority of posts has 1 upvote. Does mongoose randomize then? Sounds really strange if it did
If anyone can help me figure this out i would be very thankful
Santiago Trujillo
Basically your question is similar to pagination.
Because your multiple documents contain same value of upvotes, mongo does not able to recognise the difference(between same values) and can give same document over and over.
For example your suppose your limit is 2 and following are your documents.
[{
upvotes: 1,
doc: "a"
}, {
upvotes: 2,
doc: "b"
}, {
upvotes: 2,
doc: "c"
}, {
upvotes: 3,
doc: "d"
}]
Now if you use sort with upvotes: -1 and limit 2
You might get at first page
[{
upvotes: 3,
doc: "d"
}, {
upvotes: 2, // here mongo fails to make difference
doc: "c" // document c
}]
or can give
[{
upvotes: 3,
doc: "d"
}, {
upvotes: 2, // here mongo fails to make difference
doc: "b" // document b
}]
Means mongo randomly throws the documents having same sort field value.
Solution is too simple here just put _id accordingly
const posts = await Seed.find({ status: 'APPROVED', 'color.name': color})
.sort({upvotes: -1, _id: -1 })
.skip(parseInt(skip) || 0)
.limit(8)
.exec()