Question

我正在使用Node和Express构建电影API。我的过滤器函数未返回该值，到目前为止，我的代码如下：

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

过滤器功能是否有问题？即使我从URL传递了params值，它也仅返回[]。

这是我的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

我的过滤器函数未返回值...仅返回[]

您的过滤器代码可以正常运行，只需要进行较小的错字修复（在下面的注释中突出显示）：

/* 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)

希望这会有所帮助。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());
  }
}

尝试上面的代码，它将解决您的问题。

过滤器功能不返回值

2 个答案: