過濾函數不返回值

Question

我正在使用 Node 和 Express 構建電影 API。 我的過濾器函數沒有返回值，到目前為止我的代碼如下：

class MovieStore{
  constructor(){
    this.movieData = require('./db/database.json');
  }
  all(){
    return this.movieData;
  }
  findMovie(tittle){
    return this.movieData.filter(movie => movie.Tittle === tittle);
  }
}

過濾功能有問題嗎？ 即使我從 URL 傳遞了 params 值，它也只返回[] 。

這是我的json：

 [  
   {  
      "Title":"Guardians of the Galaxy Vol. 2",
      "Year":"2017",
      "Rated":"PG-13",
      "Released":"05 May 2017",
      "Runtime":"136 min",
      "Genre":"Action, Adventure, Comedy",
      "Director":"James Gunn",
      "Writer":"James Gunn"
   }
]

Answer 1

我的過濾器函數沒有返回值......它只返回 []

您的過濾器代碼工作正常，只需要一個小的錯字修復（在下面的評論中突出顯示）：

 /* define our test database */ const inMemoryDatabase = [ { "Title":"Guardians of the Galaxy Vol. 2", "Year":"2017", "Rated":"PG-13", "Released":"05 May 2017", "Runtime":"136 min", "Genre":"Action, Adventure, Comedy", "Director":"James Gunn", "Writer":"James Gunn" }, { "Title":"Pacific Rim", "Year":"2013", "Director":"Guillermo del Toro", "Writer":"Travis Beacham" } ] /* define your class */ class MovieStore{ constructor(){ this.movieData = inMemoryDatabase } all(){ return this.movieData; } findMovie(tittle){ return this.movieData.filter(movie => movie.Title === tittle); // <- just fixed your typo here; the json database was using key "Title". } } /* create instance of your MovieStore class */ const concreteMovieStore = new MovieStore() console.log("ALL MOVIES IN STORAGE:\\n", concreteMovieStore.all()) /* test filter function */ const movie = concreteMovieStore.findMovie("Guardians of the Galaxy Vol. 2") console.log("SEARCH RESULT: ", movie)

希望這可以幫助。 干杯!

Answer 2

//in .db/database.json
module.exports = [{ 
  "Title":"Guardians of the Galaxy Vol. 2",
  "Year":"2017",
  "Rated":"PG-13",
  "Released":"05 May 2017",
  "Runtime":"136 min",
  "Genre":"Action, Adventure, Comedy",
  "Director":"James Gunn",
  "Writer":"James Gunn"
}];


const movieData  = require('./db/database.json');;
class MovieStore{
  constructor(){}
  all(){
    return movieData;
  }
  findMovie(tittle){
    return movieData.filter(movie => movie.Tittle.toLowerCase() === tittle.trim().toLowerCase());
  }
}

試試上面的代碼，它會解決你的問題。