Unable to sort embedded array of subdocuments

[Vladimir (Vladimir R.)]

I have an endpoint that updates products and among other things that use $set and $unset it also optionally uses $push whenever a product delivery status is updated. I have found the following documentation page that shows how to use $sort during update: https://www.mongodb.com/docs/manual/reference/operator/update/sort/#up._S_sort

Unfortunately, I was not able to sort the statusJournal array of subdocuments inside my Product document.

The statusJournal array is structured as follows:

    "statusJournal" : [
        {
            "status" : "PRODUCT_CREATED",
            "date" : ISODate("2023-08-02T13:27:37.415+0000"),
            "description" : "test",
        },
        {
            "status" : "PRODUCT_OUT_FOR_DELIVERY",
            "date" : ISODate("2023-08-30T22:00:00.000+0000"),
            "description" : "test2",
        },
        {
            "status" : "PRODUCT_DELIVERED",
            "date" : ISODate("2023-08-03T22:00:00.000+0000"),
        }
    ],

The code that performs the potential $push (among other things described above) looks like this:

    const patchedProduct = await updateProduct(
        {productId: req.params.productId},
        {$set: patchProduct, $unset: patchProductUnsetQuery,
            $push: {statusJournal: {$each: [statusJournalEntry]}, $sort: {date: 1}}});

As you can see, I am attempting to (re)sort the array of subdocuments based on the date field value whenever a new status object is pushed, however it does not work, and a new pushed subdocument is simply placed at the end of the array. As you can see in the statusJournal example provided above, after pushing the PRODUCT_DELIVERED subdocument it appears below the PRODUCT_OUT_FOR_DELIVERY subdocument, even though the date is lesser.

What am I doing wrong?

Thanks

[Vladimir (Vladimir R.)]

OR: Does it only sort the input elements and don’t touch the elements in the array that already exist?

[steevej (Steeve Juneau)]

According to the documentation you share you are using the syntax wrong by having the { and } and the wrong place. I think it should be

$push: { statusJournal: { $each: [ statusJournalEntry ] , $sort: {date: 1} }

[Vladimir (Vladimir R.)]

Thank you very much @steevej. Nice catch