获取 objects 的数组，其中布尔值为真

Question

这是我的collection

{
      "_id": "bRu9ExERzz8PCDwRp",
      "persian_title": "عنوان پارسی",
      "english_title": "english title",
      "price": 5000,
      "offer_price": 2000,
"free_for_all": false,
      "is_offer": false,
      "author_id": "JH3hJGsuYFnRLFLWY"
      "Seasons": [
        {
          "title": "intro",
          "free_for_all": false,
          "Episodes": [
            {
              "title": "first episode",
              "length": "12",
              "url": "0.mp4",
              "free_for_all": true
            },
            {
              "title": "second episode",
              "length": "05",
              "url": "1.mp4",
              "free_for_all": false
            }
          ]
        }
      ]
    }

我正在尝试获取 free_for_all 为真的剧集。试过这个但它不起作用。

db.courses.find({_id:"bRu9ExERzz8PCDwRp"}, {
"Seasons": { 
        "$elemMatch": {
            "Episodes": {
                "$elemMatch": {
                    "free_for_all": true,
                }
            }
        }
    }
})

结果就像这个查询：

db.courses.find({_id:"bRu9ExERzz8PCDwRp"})

我怎样才能只获得免费剧季和剧集？

Answer 1

您的问题对于包含非免费剧集的免费季的预期结果含糊不清，反之亦然，非免费季中的免费剧集。因此，我假设您只想要免费且属于免费季的剧集。这就是以下内容（未测试）：

_.reduce(db.courses.findOne({_id:"bRu9ExERzz8PCDwRp"}).Seasons, function(all, s) {
     if (s.free_for_all) {
         all = _.reduce(s.Episodes, function(memo, e) {
              if (e.free_for_all) memo.push(e);
              return memo;
         }, all);
     }
     return all;
}, []);

如果您想要所有免费剧集或免费季的一部分：

_.reduce(db.courses.findOne({_id:"bRu9ExERzz8PCDwRp"}).Seasons, function(all, s) {
     if (s.free_for_all) {
        all = all.concat(s.Episodes);
     } else {
         all = _.reduce(s.Episodes, function(memo, e) {
              if (e.free_for_all) memo.push(e);
              return memo;
         }, all);
     }
     return all;
}, []);

获取 objects 的数组，其中布尔值为真

get array of objects where boolean is true

mongodb

nosql

meteor