Filter List of Object-Nested Objects with Object Containing Key-Array Pair

Question

I tried to came up with the most descriptive title.

I came up with a solution but its terribly inefficient as its in the order of O(n^4) or so, which is pathetic.

I am trying to filter and return a list of objects based on a filter-object and matching key values.

I will have a list of movies, movieList , and I will return all movies that meet all the key-value pairs that are contained within the movieFilter object. In the case of genre , the movie must be one of the genres. Since sales is not in the filter we do not filter based on it.

let movieFilter = {
  "genre": ["Action", "Romance"],
  "director": "Bob",
  "writer": ["Jim", "Dave", "Alice"],
  "duration": "2"
}

let movie = {
  "genre" : "Action",
  "people": {
    "director": "Bob",
    "writer": "Alice"   
  }
  "boxoffice": "9,000,000",
  "duration": "2"
}

let movies = [{
  "genre" : "Action",
  "people": {
    "director": "Bob",
    "writer": "Alice"   
  }
  "boxoffice": "9,000,000",
  "duration": "2"
}, 
{
  "genre" : "Comedy",
  "people": {
    "director": "Rose",
    "writer": "Mike"   
  }
  "boxoffice": "12,000,000",
  "duration": "3"
}]

The issue I'm having is that because some filters (like the genre filter) are in arrays and some movie keys (like people ) are nested within an object I am forced to nest loops within loops, which makes the time complexity grow.

I could change the way the filter is structures, but the way it currently is makes sense to me. The movie object format is something I cannot change.

Any suggestion on how I could tackle this would be appreciated.

Answer 1

It can be done using filter method and some method:

 let movieFilter = { "genre": ["Action", "Romance"], "director": "Bob", "writer": ["Jim", "Dave", "Alice"], "duration": "2" } let movies = [ { "genre": "Action", "people": { "director": "Bob", "writer": "Alice" }, "boxoffice": "9,000,000", "duration": "2" }, { "genre": "Comedy", "people": { "director": "Rose", "writer": "Mike" }, "boxoffice": "12,000,000", "duration": "3" }] const result = movies.filter(f => movieFilter.genre.some(ge=> ge == f.genre) && movieFilter.director == f.people.director && movieFilter.writer.some(wr => wr == f.people.writer) && movieFilter.duration == f.duration ); console.log(result);

UPDATE:

Thanks to @MkeSpaGuy comment. I've remade a little bit approach to filter your items.

It is slightly optimized version using key to check whether filter conditions are satisfied:

 let movieFilter = { "genre": ["Action", "Romance"], "director": "Bob", "writer": ["Jim", "Dave", "Alice"], "duration": "2" } movieFilter.genre = movieFilter.genre.reduce((a, key) => ({...a, [key]: 1}), {}); movieFilter.writer = movieFilter.writer.reduce((a, key) => ({...a, [key]: 1}), {}); let movies = [{ "genre": "Action", "people": { "director": "Bob", "writer": "Alice" }, "boxoffice": "9,000,000", "duration": "2" }, { "genre": "Comedy", "people": { "director": "Rose", "writer": "Mike" }, "boxoffice": "12,000,000", "duration": "3" }]; const result = movies.filter(f => movieFilter.genre[f.genre] && movieFilter.director == f.people.director && movieFilter.writer[f.people.writer] && movieFilter.duration == f.duration ); console.log(result);

Answer 2

Consider replacing your arrays with objects inside your movieFilter.

 let movieFilter = { genre: { Action: true, Romance: true }, director: "Bob", writer: { Jim: true, Dave: true, Alice: true }, duration: "2" }; let movies = [ { genre: "Action", people: { director: "Bob", writer: "Alice" }, boxoffice: "9,000,000", duration: "2" }, { genre: "Comedy", people: { director: "Rose", writer: "Mike" }, boxoffice: "12,000,000", duration: "3" } ]; const filterOnMovieFilter = movie => { const { genre, people, duration } = movie; const { writer, director } = people || {}; return ( movieFilter.genre[genre] && movieFilter.writer[writer] && movieFilter.duration === duration && movieFilter.director === director ); }; console.log(movies.filter(filterOnMovieFilter));

However, please avoid premature optimization . You will not notice optimization when filtering 10,000 items in a modern browser.
(Notice I said filter and not display) I often do things that are less efficient in favor of simple, concise, immutable, readable and useful code. If you are targeting a feature phone or find a real performance bottleneck, you will need to measure with performance monitoring tools. The JavaScript engine optimizations are continuously improving and results are often surprising.