根据文件顺序列表对骨干集合进行排序

Question

我继承了一个系统，该系统利用需要根据一系列值进行排序的文件的 Backbone 集合。当您将不同的文件滑入视图中的某个位置时，将保存顺序变量。它大多数情况下都可以工作，但偶尔会出现无法根据 files_order 列表中的值正确排序的情况。我发现使用无符号右移最接近工作，但代码返回奇怪的结果，因为集合中的许多文件不在 files_order 中。

对于filecollectionid = 1，系统结果为： 36528,36524,36529,35526,36523,36525,36530,36531

正确的顺序应该是： 36528,36523,36524,36525,35526,36529,36530,36531

我假设列表中不存在的变量的无符号右移导致了问题。任何帮助将不胜感激。

collection = new Backbone.Collection([
  { id: 36523, name: "File 1", filecollectionid: 1 },
  { id: 36524, name: "File 2", filecollectionid: 1 },
  { id: 36525, name: "File 3", filecollectionid: 1 },
  { id: 36526, name: "File 4", filecollectionid: 1 },
  { id: 36528, name: "File 5", filecollectionid: 1 },
  { id: 36529, name: "File 6", filecollectionid: 1 },
  { id: 36530, name: "File 7", filecollectionid: 1 },
  { id: 36531, name: "File 8", filecollectionid: 1 },
  { id: 36476, name: "Video 1", filecollectionid: 6 },
  { id: 36520, name: "Video 2", filecollectionid: 6 },
  { id: 36527, name: "Video 3", filecollectionid: 6 }
]);

sections = {
 "id": 1,
"files_order" : [36503,36513,36505,36506,36507,36508,36509,36510,36511,36521,36528,36522,35523,36524]
}

collection.sort(function(a,b) {
    // Lets group files by the file collection id first
    if(a.filecollectionid != b.filecollectionid){
        return a.filecollectionid - b.filecollectionid;
    }

    // Lets try to use the files_order variable
    try {
        // Get the files_order field
        var files_order = _.find(sections, function(section) {
            // They should both have the same filecollectionid
            return a.filecollectionid == section.id;
        }).files_order;

        files_order = _.map(JSON.parse(files_order.toString()), function(item) {
            return parseInt(item);
        });

        // use unsigned right shift to keep the original and add the unadded to the end
        return (files_order.indexOf(a.id) >>> 0) - (files_order.indexOf(b.id) >>> 0);
    } catch(e) {
        // If no sorting order this really should be oldest first and newest last.
        a = a.id;
        b = b.id;
        return ((a < b) ? -1 : ((a > b) ? 1 : 0));
    }
});

Answer 1

假设你可以使用当前版本的JS：

(() => {
  const collection = [
    { id: 36524, name: "File 2", filecollectionid: 1 },
    { id: 36523, name: "File 1", filecollectionid: 1 },
    { id: 36525, name: "File 3", filecollectionid: 1 },
    { id: 36520, name: "Video 2", filecollectionid: 6 },
    { id: 36526, name: "File 4", filecollectionid: 1 },
    { id: 36528, name: "File 5", filecollectionid: 1 },
    { id: 36529, name: "File 6", filecollectionid: 1 },
    { id: 36476, name: "Video 1", filecollectionid: 6 },
    { id: 36530, name: "File 7", filecollectionid: 1 },
    { id: 36531, name: "File 8", filecollectionid: 1 },
    { id: 36527, name: "Video 3", filecollectionid: 6 },
  ];

  const sections = [
    {
      id: 1,
      files_order: [36503, 36513, 36505, 36506, 36507, 36508, 36509, 36510, 36511, 36521, 36528, 36522, 35523, 36524],
    },
  ];

  const getOrderMap = (collectionId) => {
    const order = sections.find((s) => s.id === collectionId)?.files_order ?? [];
    return new Map(order.map((v, i) => [v, i]));
  };

  collection.sort(function (a, b) {
    if (a.filecollectionid != b.filecollectionid) {
      return a.filecollectionid - b.filecollectionid;
    }
    const map = getOrderMap(a.filecollectionid);
    const [ai, bi] = [map.get(a.id), map.get(b.id)];
    return ai === bi ? a.id - b.id : ai === undefined ? 1 : bi === undefined ? -1 : ai - bi;
  });

  // Debugging purposes
  console.log(collection);
})();