java - 如何在java中对复杂集合mongodb中的列表进行排序和获取？

Question

这是我在 mongodb 中的数据库集合

{
    "_id" : 0,
    "name" : "+Anima",
    "author" : "MUKAI Natsumi",
    "type" : [ 
        "Adventure", 
        "Fantasy"
    ],
    "chapters" : [ 
        {
            "chapterName" : "+Anima 56",
            "chapterLink" : "http://...",
            "groupTranslate" : "Manga Palace Group",
            "dateUpload" : 1359478800000,
            "chapterNumber" : 56.0000000000000000,
            "images" : [ 
                 "img0", 
                "img1", 
                "img2", 
                "img3"
            ]
        }, 
        {
            "chapterName" : "+Anima 55",
            "chapterLink" : "http://....",
            "groupTranslate" : "Manga Palace Group",
            "dateUpload" : 1410109200000,
            "chapterNumber" : 55.0000000000000000,
            "images" : [ 
                "img0", 
                "img1", 
                "img2", 
                "img3"
            ]
        }
    ]
}   

我无法使用java代码在mongodb中找到按“dateUpload”排序的列表章节。请帮忙。

Answer 1

蒙戈 $aggregation 将解决您的问题。下面先查询$unwind您的 chapters 数组，然后对 dateUpload

进行排序

    db.collectionName.aggregate({
    "$unwind": "$chapters" // unwind breaks the chapters array
}, {
    "$sort": {
    "chapters.dateUpload": -1 // then seperated chapters array sorted by dateUpload
    }
}, {
    "$group": {
    "_id": "$_id",
    "chapters": {
        "$push": "$chapters" // group used for grouping chapters array
    }
    }
}).pretty()

为了将上述查询转换为 Java 代码格式，请遵循下面的 mongo 聚合 Java 驱动程序代码。 Java Driver and Aggregation Framework