Finding the most popular genre

Find from the 'movies' collection in MongoDB with the most common genre among the movies.

Structure of 'movies' collection:

{
    _id: ObjectId("573a1390f29313caabcd42e8"),
plot: 'A group of bandits stage a brazen train hold-up, only to find a determined posse hot on their heels.',
genres: [ 'Short', 'Western' ],
runtime: 11,
cast: [
      'A.C. Abadie',
      "Gilbert M. 'Broncho Billy' Anderson",
      'George Barnes',
      'Justus D. Barnes'
    ],
poster: 'https://m.media-amazon.com/images/M/MV5BMTU3NjE5NzYtYTYyNS00MDVmLWIwYjgtMmYwYWIxZDYyNzU2XkEyXkFqcGdeQXVyNzQzNzQxNzI@._V1_SY1000_SX677_AL_.jpg',
title: 'The Great Train Robbery',
fullplot: "Among the earliest existing films in American cinema - notable as the first film that presented a narrative story to tell - it depicts a group of cowboy outlaws who hold up a train and rob the passengers. They are then pursued by a Sheriff's posse. Several scenes have color included - all hand tinted.",
languages: [ 'English' ],
released: ISODate("1903-12-01T00:00:00.000Z"),
directors: [ 'Edwin S. Porter' ],
rated: 'TV-G',
awards: { wins: 1, nominations: 0, text: '1 win.' },
lastupdated: '2015-08-13 00:27:59.177000000',
year: 1903,
imdb: { rating: 7.4, votes: 9847, id: 439 },
countries: [ 'USA' ],
type: 'movie',
tomatoes: {
viewer: { rating: 3.7, numReviews: 2559, meter: 75 },
fresh: 6,
critic: { rating: 7.6, numReviews: 6, meter: 100 },
rotten: 0,
lastUpdated: ISODate("2015-08-08T19:16:10.000Z")
    }
.....

Query:

db.movies.aggregate([
  {
    $unwind: '$genres'
  },
  {
    $group: {
      _id: '$genres',
count: { $sum: 1 }
    }
  },
  {
    $sort: { count: -1 }
  },
  {
    $limit: 1
  }
])

Output:

[ { _id: 'Drama', count: 13789 } ]

Explanation:

The said query in MongoDB returns the most frequently occurring genre from the 'movies' collection in MongoDB.

The $unwind stage separates document for each element in the "genres" array and count the occurrences of each genre individually in each group.

The $group stage groups the documents based on the "genres" field. The _id field is used to specify the grouping key.

Inside the $group stage, the $sum aggregation operator increments the count for each occurrence of a genre. The 1 passed to $sum represents adding 1 for each document, effectively counting the occurrences of each genre.

The $sort stage sorts the documents based on the "count" field in descending order.

The $limit stage limits only the first document, effectively retrieving the genre with the highest count.

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