Spotify 清除播放列表拖放 [英] Spotify Clear Playlist Drag and Drop

问题描述

当您将艺术家拖放到我的侧边栏中的应用中时，我会构建一个临时播放列表.每次我将新艺术家拖入我的应用程序时，它都会在前一个之后构建一个新列表，而不会清除旧列表.(注意这里缺少一些可能不需要的代码).

When you drag/drop an Artist into my app in the sidebar, I build a temporary playlist. Every time I drag a new Artist into my app, it builds a new list after the previous, WITHOUT clearing out the old one. (Note there is some code missing from here that is probably not needed).

我的问题:我如何清除或删除当前构建的播放列表然后构建一个新的，每次我将一个艺术家拖放到我的应用程序中?我怀疑它需要在 getRelated() 中调用?

My question: how do I clear out or remove the current built playlist THEN build a new one, every time I drag/drop an Artist into my app? I suspect it would need to be called inside getRelated()?

 models.application.addEventListener('dropped', sidebarDropEventListener);

 function sidebarDropEventListener() {
   for(var i = 0; i < models.application.dropped.length; i++){
      var draggedItem = models.application.dropped[i];
      updateFromDragged(draggedItem.uri);
   }
 }

 function updateFromDragged(droppedUri) {
   // If dropped item is an artist
   if(droppedUri.indexOf('artist') >= 0) {
      getRelated(droppedUri);
   } else {
      console.warn('Dropped item is not an artist');
   }
}

     // Build playlist
     function buildList(trackURIArray){
       var arr = trackURIArray;

       models.Playlist
        .createTemporary("myTempList_" + new Date().getTime())
        .done(function (playlist){ 

        playlist.load("tracks").done(function() {

          playlist.tracks.add.apply(playlist.tracks, arr).done(function(){
            // Create list
            var list = List.forCollection(playlist);

            // Populate DOM
            $('#playlistContainer').append(list.node);
            list.init();
          });
      });
    });
  }

    // Get Related
    function getRelated(artist_uri){

      models.Artist
      .fromURI(artist_uri)
      .load('related','name')
      .done(function (artist){

        artist.related.snapshot().done(function (snapshot){
          snapshot.loadAll().done(function (artists){

            var promises = [];

            for(var i = 0; i < artists.length; i++){
              var promise = getTopTrack(artists[i], 1);
              promises.push(promise);
            }

            models.Promise.join(promises)
              .done(function (tracks){
                buildList(tracks);
              })
              .fail(function (tracks){
                buildList(tracks);
              });
          });
        });
      });
    }

推荐答案

我最终做的是在顶部创建一个全局变量tempList".然后将播放列表存储在我的buildList"函数中.在updateFromDragged"中，我只使用tempList.tracks.clear"来清除存储的播放列表曲目.

What I ended up doing was creating a global variable "tempList" at the top. Then storing the playlist inside my "buildList" function. Inside "updateFromDragged," I just use "tempList.tracks.clear" to clear out the stored playlist tracks.

我也应该在这里使用removeTemporary"吗?

Should I use "removeTemporary" here as well?

var tempList;

  // Build playlist
  function buildList(trackURIArray){
    var arr = trackURIArray;
    var date = new Date().getTime();

    models.Playlist
      // prevents appending new tracks on refresh
      .createTemporary("myTempList_" + date)
      .done(function (playlist){ 

        // Store created playlist
        tempList = playlist;

        playlist.load("tracks").done(function() {

          playlist.tracks.add.apply(playlist.tracks, arr).done(function(){
            // Create list
            var list = List.forCollection(playlist, {
              style: 'rounded',
              layout: 'toplist'
            });

            // Hide loading
            $loading.hide();

            // Populate DOM
            $('#playlistContainer').append(list.node);
            list.init();
          });
      });
    });

function updateFromDragged(droppedUri) {

    // Clear out old tracks
    tempList.tracks.clear();

    // Remove the temporary ones not in use to reduce resource load
    models.Playlist.removeTemporary( models.Playlist.fromURI(tempList) );

    // If dropped item is an artist
    if(droppedUri.indexOf('artist') >= 0) {
      getRelated(droppedUri);
    } else {
        console.warn('Dropped item is not an artist');
    }    

  }

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