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$sortByCount mongodb

Liubomyr Siusar answered on October 5, 2022 Popularity 7/10 Helpfulness 3/10

answer $sortByCount mongodb

$sortByCount mongodb

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{ "_id" : 1, "title" : "The Pillars of Society", "tags" : [ "painting", "satire", "Expressionism", "caricature" ] }
{ "_id" : 2, "title" : "Melancholy III", "tags" : [ "woodcut", "Expressionism" ] }
{ "_id" : 3, "title" : "Dancer", "tags" : [ "oil", "Surrealism", "painting" ] }
{ "_id" : 4, "title" : "The Great Wave off Kanagawa", "tags" : [ "woodblock", "ukiyo-e" ] }
{ "_id" : 5, "title" : "The Persistence of Memory", "tags" : [ "Surrealism", "painting", "oil" ] }
{ "_id" : 6, "title" : "Composition VII", "tags" : [ "oil", "painting", "abstract" ] }
{ "_id" : 7, "title" : "The Scream", "tags" : [ "Expressionism", "painting", "oil" ] }
{ "_id" : 8, "title" : "Blue Flower", "tags" : [ "abstract", "painting" ] }

Assume we execute next:
db.exhibits.aggregate( [ { $unwind: "$tags" },  { $sortByCount: "$tags" } ] )

1) result of $unwind:
// for first element
{ "_id" : 1, "title" : "The Pillars of Society", "tags" :"caricature"  }
{ "_id" : 1, "title" : "The Pillars of Society", "tags" : "Expressionism" }
{ "_id" : 1, "title" : "The Pillars of Society", "tags" : "satire"  }
{ "_id" : 1, "title" : "The Pillars of Society", "tags" : "painting" }

// for second elem
{ "_id" : 2, "title" : "Melancholy III", "tags" : "Expressionism" }
{ "_id" : 2, "title" : "Melancholy III", "tags" : "woodcut" }

// and so on
{ "_id" : 3, "title" : "Dancer", "tags" : "painting" }
...

2) next stage with $sortByCount:

// we get all of these
{ "_id" : 1, "title" : "The Pillars of Society", "tags" :"caricature"  }
{ "_id" : 1, "title" : "The Pillars of Society", "tags" : "Expressionism" }
{ "_id" : 1, "title" : "The Pillars of Society", "tags" : "satire"  }
{ "_id" : 1, "title" : "The Pillars of Society", "tags" : "painting" }
{ "_id" : 2, "title" : "Melancholy III", "tags" :  "Expressionism" }
{ "_id" : 2, "title" : "Melancholy III", "tags" : "woodcut" }
{ "_id" : 3, "title" : "Dancer", "tags" : "painting" }
...

// and calculate next

{ "_id" : "painting", "count" : 6 }
{ "_id" : "oil", "count" : 4 }
{ "_id" : "Expressionism", "count" : 3 }
{ "_id" : "Surrealism", "count" : 2 }
{ "_id" : "abstract", "count" : 2 }
{ "_id" : "woodblock", "count" : 1 }
{ "_id" : "woodcut", "count" : 1 }
{ "_id" : "ukiyo-e", "count" : 1 }
{ "_id" : "satire", "count" : 1 }
{ "_id" : "caricature", "count" : 1 }


// as result we get counts of each tag from all arrays of our elements

Popularity 7/10 Helpfulness 3/10 Language javascript

Source: Grepper

Tags: javascript mongodb

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Contributed on Oct 05 2022

Liubomyr Siusar

0 Answers Avg Quality 2/10

$sortByCount mongodb

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