CODEWITHSUNDEEP
javascriptmongodbmongoosemongodb-queryaggregation-framework
HARDY8118
HARDY8118

Reputation: 702

Mongodb aggregate to sort items with most common items in array?

An item in collection contains an array of strings. I would like to find and sort items with most matching elements in array.

Consider a collection:

[
    {
        "item_name":"Item_1",
        "tags":["A","B","C","D","E"]
    },
    {
        "item_name":"Item_2",
        "tags":["A","B","D","E","G"]
    },
    {
        "item_name":"Item_3",
        "tags":["B","C","E","H"]
    }

]

I want to sort the collection based on an array like ["B","D","G","F"] which will return

[

    {
        "item_name":"Item_2",
        "tags":["A","B","D","E","G"]
    },
    {
        "item_name":"Item_1",
        "tags":["A","B","C","D","E"]
    },
    {
        "item_name":"Item_3",
        "tags":["B","C","E","H"]
    }

]

The expected order will be Item_2,Item_1 and then Item_3 since,

If not in mongodb, JavaScript methods will also be appreciated

Upvotes: 2

Views: 566

Answers (2)

thammada.ts
thammada.ts

Reputation: 5245

If the values in tags are unique, you can use the size of the intersections of tags and the query array using $size and $setIntersection

db.collection.aggregate([
  {
    $set: {
      matchedCount: {
        $size: {
          $setIntersection: ["$tags", ["B","D","G","F"]]
        }
      }
    }
  },
  {
    $sort: {
      matchedCount: -1
    }
  }
])

Upvotes: 5

Jiří Pospíšil
Jiří Pospíšil

Reputation: 14402

You can use $setIntersection to get the number of intersecting items and then $sort based on the computed score.

db.collection.aggregate([
  {
    $project: {
      _id: 0,
      item_name: "$item_name",
      tags: "$tags",
      score: {
        $let: {
          vars: {
            intersection: {
              $setIntersection: [
                "$tags",
                [
                  "B",
                  "D",
                  "G",
                  "F"
                ]
              ]
            }
          },
          in: {
            $size: "$$intersection"
          }
        }
      }
    }
  },
  {
    $sort: {
      score: -1
    }
  }
])

https://mongoplayground.net/p/tpDTtVKetFT

Upvotes: 2

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