json 文件中有多少种类型？

Question

我有电影的大 json。这个 json 有 2 个数组“流派”和“电影”。部分 json 如下所示：

{
    "genres": [
        "Comedy",
        "Fantasy",
        "Crime",
        "Drama",
        "Music",
        "Adventure",
        "History",
        "Thriller",
        "Animation",
    ],
    "movies": [
        {
            "id": 1,
            "title": "Beetlejuice",
            "year": "1988",
            "runtime": "92",
            "genres": [
                "Comedy",
                "Fantasy"
            ],
            "director": "Tim Burton",
            "actors": "Alec Baldwin, Geena Davis, Annie McEnroe, Maurice Page",
            "plot": "A couple of recently deceased ghosts contract the services of a \"bio-exorcist\" in order to remove the obnoxious new owners of their house.",
            "posterUrl": "https://m.media-amazon.com/images/M/MV5BZDdmNjBlYTctNWU0MC00ODQxLWEzNDQtZGY1NmRhYjNmNDczXkEyXkFqcGdeQXVyMTQxNzMzNDI@._V1_FMjpg_UX1000_.jpg"
        },
        {
            "id": 2,
            "title": "The Cotton Club",
            "year": "1984",
            "runtime": "127",
            "genres": [
                "Crime",
                "Drama",
                "Music"
            ],
            "director": "Francis Ford Coppola",
            "actors": "Richard Gere, Gregory Hines, Diane Lane, Lonette McKee",
            "plot": "The Cotton Club was a famous night club in Harlem. The story follows the people that visited the club, those that ran it, and is peppered with the Jazz music that made it so famous.",
            "posterUrl": "https://images-na.ssl-images-amazon.com/images/M/MV5BMTU5ODAyNzA4OV5BMl5BanBnXkFtZTcwNzYwNTIzNA@@._V1_SX300.jpg"
        },
        {
            "id": 3,
            "title": "The Shawshank Redemption",
            "year": "1994",
            "runtime": "142",
            "genres": [
                "Crime",
                "Drama"
            ],
            "director": "Frank Darabont",
            "actors": "Tim Robbins, Morgan Freeman, Bob Gunton, William Sadler",
            "plot": "Two imprisoned men bond over a number of years, finding solace and eventual redemption through acts of common decency.",
            "posterUrl": "https://m.media-amazon.com/images/M/MV5BMTQ1ODM2MjY3OV5BMl5BanBnXkFtZTgwMTU2MjEyMDE@._V1_.jpg"
        },

和其他143部电影...

我需要找到在“电影”数组中使用“流派”数组的所有电影有多少流派。

我做了这个代码：

const comedy = props.movies.map(movie => movie.genres.filter(genre => genre === "Comedy").length)
        .reduce((total, count) => total + count, 0);
    
const fantasy = props.movies.map(movie => movie.genres.filter(genre => genre === "Fantasy").length)
        .reduce((total, count) => total + count, 0);
    
const crime = props.movies.map(movie => movie.genres.filter(genre => genre === "Crime").length)
        .reduce((total, count) => total + count, 0);

我为其他 18 种类型制作了它。

我可以缩短这段代码吗？谢谢

Answer 1

相当简单，因为您在同一对象中有流派列表：

const all = Object.fromEntries(
    props.genres.map(genre => 
     [
       genre, 
       props.movies.map(
           movie => movie.genres.filter(filmGenre => filmGenre === genre).length
       ).reduce((total, count) => total + count, 0)
     ]
    )
  );

这将导致类似的结果

{
  "comedy": 42,
  "action": 0
}

供参考，来自条目：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/fromEntries

参见下面的示例（为了便于阅读，我已经从电影中删除了额外未使用的属性）

const props = {
  "genres": [
    "Comedy",
    "Fantasy",
    "Crime",
    "Drama",
    "Music",
  ],
  "movies": [{
      "title": "Beetlejuice",
      "genres": [
        "Comedy",
        "Fantasy"
      ],
    },
    {
      "title": "The Cotton Club",
      "genres": [
        "Crime",
        "Drama",
        "Music"
      ],
    },
    {
      "title": "The Shawshank Redemption",
      "genres": [
        "Crime",
        "Drama"
      ],
    }
  ]
};
const all = Object.fromEntries(
  props.genres.map(genre => [
    genre,
    props.movies.map(
      movie => movie.genres.filter(filmGenre => filmGenre === genre).length
    ).reduce((total, count) => total + count, 0)
  ])
);
console.log(all);

Answer 2

这是一个只对电影迭代一次的解决方案（如果电影没有在其

genres

数组中声明重复类型，则此解决方案有效）

const createInitValue = () => props.genres
  .reduce((obj, genre) => ({...obj, [genre]: 0}), {});

const nbMoviesByGenre = props.movies
  .flatMap(movie => movie.genres)
  .reduce((res, genre) => {
    if (!isNaN(res[genre])) {
      res[genre]++;
    }
    return res;
  }, createInitValue());