Here is my data:
{
{ "_id" : ObjectId("623a92139e19f99295167786"),
"headline" : "headline1",
"comments" : [
{"userID" : ObjectId("623a7b199e19f99295167776"),
"time" : ISODate("2022-03-24T10:20:23Z")},
{"userID" : ObjectId("623a7b199e19f99295167776"),
"time" : ISODate("2022-03-25T10:20:23Z")},
]
},
{ "_id" : ObjectId("623be3ce9e19f99295167787"),
"headline" : "headline2",
"comments" : [ ]
}
}
The inner array comments may or may not contain some elements. I want to find an object with the _id that matches the string variable my_id, with its inner array comments sorted in the reverse order of time. I currently have:
col.aggregate([
{$match: {_id: monk.id(my_id)}},
{$unwind: "$comments"},
{$sort: {"comments.time":-1}},
{$group: {_id: "$_id", headline: {$first:"$headline"},
comments:{$push:"$comments"}}}
]).then((result) => {
console.log(JSON.stringify(result));
});
This works fine when the comments array has some elements but returns [] for the entire object if the array is empty. May I get some help on how to return the content even when the array is empty?
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