MongoDB - group documents by field value

Question

I need to group following documents by featured and trending.

[
    {
        "_id" : ObjectId("5f22546cd49ffe0d6f087a2e"),
        "title" : "....",
        "image" : "...",
        "featured" : true,
        "trending" : false,
        "creationDate" : ISODate("2020-07-30T05:02:36.592Z")
    },
    {
        "_id" : ObjectId("5f22546cd49ffe0d6f087a2f"),
        "title" : "Cras non dolor",
        "image" : "...",
        "featured" : false,
        "trending" : true,
        "creationDate" : ISODate("2020-07-30T05:02:36.592Z")
    }
]

So, after grouping they should be in following format -

[
    {
        _id: null,
        featured: [
            {
                "_id" : ObjectId("5f22546cd49ffe0d6f087a2e"),
                "title" : "....",
                "image" : "...",
                "featured" : true,
                "trending" : false,
                "creationDate" : ISODate("2020-07-30T05:02:36.592Z")
            }
        ],
        trending: [
            {
                "_id" : ObjectId("5f22546cd49ffe0d6f087a2f"),
                "title" : "Cras non dolor",
                "image" : "...",
                "featured" : false,
                "trending" : true,
                "creationDate" : ISODate("2020-07-30T05:02:36.592Z")
            }
        ]
    }
]

How can I get this result through aggregation or any other way?

I have been trying with aggregate $group. But I can't figure out how can I $group via featured/trending value with equal true.

So, I don't need corresponding false value when grouping them. Also, there might have other fields like highlighted etc along with featured trending.

Answer 1

This is quite easy to achieve, the easiest way to do it is using $facet

db.collection.aggregate([
  {
    $facet: {
      featured: [
        {
          $match: {
            "featured": true
          }
        }
      ],
      trending: [
        {
          $match: {
            "trending": true
          }
        }
      ]
    }
  }
])

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