mongodb - 使用 mongodb 聚合进行数据复制

Question

我使用了 MongoDB 聚合，当我尝试使用排序和限制时，我得到了重复的记录。

正如您在下面看到的，我有 3 个文档，其中 document1 和 document2 具有相同的标题，而 document3 具有不同的视频标题.

我想按标题对文档进行分组，并按连续剧集按降序对分组的文档进行排序。

document1 和 document2 将在同一组中，并将获得唯一的 document2 然后现在我想对这个 document2 和 document3 和 video_view_count。

/* document1 */
{
    "_id" : ObjectId("580afd565706467c1bbabd70"),
    "serial_episode" : "5",
    "video_view_count" : 50.0,
    "video_data" : [ 
        {
            "video_categories" : [ 
                "Sport"
            ],
            "video_title" : "Zwyci??zca",
            "language_id" : "578f1ec6e494f9400b21fec4"
        }, 
        {
            "video_featured_text" : "",
            "video_categories" : [ 
                "Sport"
            ],
            "video_title" : "Zwyci??zca",
            "language_id" : "578f1ec6e494f9400b21fec3"
        }
    ]
}

/* document2 */
{
    "_id" : ObjectId("580afd565706467c1bbabd71"),
    "serial_episode" : "6",
    "video_view_count" : 10.0,
    "video_data" : [ 
        {
            "video_categories" : [ 
                "Sport"
            ],
            "video_title" : "Zwyci??zca",
            "language_id" : "578f1ec6e494f9400b21fec4"
        }, 
        {
            "video_featured_text" : "",
            "video_categories" : [ 
                "Sport"
            ],
            "video_title" : "Zwyci??zca",
            "language_id" : "578f1ec6e494f9400b21fec3"
        }
    ]
}

/* document3 */
{
    "_id" : ObjectId("580afd565706467c1bbabd72"),
    "serial_episode" : "",
    "video_view_count" : 11.0,
    "video_data" : [ 
        {
            "video_categories" : [ 
                "Sport"
            ],
            "video_title" : "Zwyci??zca123",
            "language_id" : "578f1ec6e494f9400b21fec4"
        }, 
        {
            "video_featured_text" : "",
            "video_categories" : [ 
                "Sport"
            ],
            "video_title" : "Zwyci??zca123",
            "language_id" : "578f1ec6e494f9400b21fec3"
        }
    ]
}          

预期输出:

我想要一个 document3 然后是 document2 的结果，因为 docuemnt1-2 组合在一起产生一个唯一的 document2 和 docuemnt2 有最新一集。我需要比较 document2 和 document3 的视频观看次数:

/* document3 */
{
    "_id": ObjectId("580afd565706467c1bbabd72"),
    "serial_episode": "",
    "video_view_count": 11,
    "video_data": [
        {
            "video_categories": [
                "Sport"
            ],
            "video_title": "Zwyci??zca123",
            "language_id": "578f1ec6e494f9400b21fec4"
        },
        {
            "video_featured_text": "",
            "video_categories": [
                "Sport"
            ],
            "video_title": "Zwyci??zca123",
            "language_id": "578f1ec6e494f9400b21fec3"
        }
    ]
},
/* document3 */
{
    "_id": ObjectId("580afd565706467c1bbabd71"),
    "serial_episode": "6",
    "video_view_count": 10,
    "video_data": [
        {
            "video_categories": [
                "Sport"
            ],
            "video_title": "Zwyci??zca",
            "language_id": "578f1ec6e494f9400b21fec4"
        },
        {
            "video_featured_text": "",
            "video_categories": [
                "Sport"
            ],
            "video_title": "Zwyci??zca",
            "language_id": "578f1ec6e494f9400b21fec3"
        }
    ]
}

当前聚合操作:

// Grouping that I have implemented 
var group = {   
    "$group": { 
        "_id":" $video_data.video_title",
        "video_rating" : { $first:" $video_rating" },
        "serial_episode" : { $first: "$serial_episode" },
        "video_view_count": { $first: "$video_view_count" },
    }
};

// Aggregate function to get that videos    
videos.aggregate([ 
    { $match: { "video_data.video_categories": query.category_name } },
    { $unwind: "$video_data" },
    { $sort: { video_view_count: -1 } },
    { $sort:{ serial_episode: -1 } },
    group,
    { $sort:{ video_view_count: -1 } },
    { $skip: skipData },
    { $limit: 10 }
], function(error, output){});

Answer 1

你为什么要解除它..？删除 unwind，它将文档与数组长度相乘..