mongodb如何对内嵌的文档进行排序? - V2EX
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hiwljun

mongodb如何对内嵌的文档进行排序?

  •  
  •   hiwljun Nov 28, 2013 8928 views
    This topic created in 4533 days ago, the information mentioned may be changed or developed.
    想对评论的查询结果按更新时间倒序显示。
    {
    comment:
    [
    {
    "author":"mongodb",
    "content":"排序",
    "datetime":2013-11-28
    },
    {
    "author":"mongodb",
    "content":"排序",
    "datetime":2013-11-29
    },
    {
    "author":"mongodb",
    "content":"排序",
    "datetime":2013-11-30
    }
    ]
    }
    10 replies    1970-01-01 08:00:00 +08:00
    lichao
        1
    lichao  
       Nov 28, 2013
    lichao
        2
    lichao  
       Nov 28, 2013
    @lichao 哦,内嵌的数组不是这样排
    hiwljun
        3
    hiwljun  
    OP
       Nov 28, 2013
    @lichao 嗯,估计只要在结果里用python去排了。
    1to3
        4
    1to3  
       Nov 28, 2013 via Android
    db.collection.find(criteria).sort({comment.datetime:-1})
    猜的。
    hiwljun
        5
    hiwljun  
    OP
       Nov 28, 2013
    @1to3 find_one的时候就不可用了。
    1to3
        6
    1to3  
       Nov 28, 2013 via Android
    db.collection.find(criteria).sort({comment.datetime:-1}).limit(1) 这个?
    1to3
        7
    1to3  
       Nov 28, 2013 via Android
    @hiwljun find 或者findOne应该是不改变文档数据的,你说到的情况,已经对文档内部数据结构修改了,先update排好序再find,或者把comment放到另一个collection,或者就如你说的先查到数据再在应用层面去排序。
    不好意思一开始没看明白你的意思。
    hiwljun
        8
    hiwljun  
    OP
       Nov 28, 2013
    @1to3 嗯,find_one返回的是一个字典,所以不能使用sort(),update的时候好像不能排序。现在的解决方法还是使用应用层面去排序了。
    mahone3297
        9
    mahone3297  
       Nov 28, 2013
    @hiwljun 如果数据量很大,需要全拿出来在应用层去排序?那不是疯了?
    当然,我也不懂mongodb。但是我猜应该是有排序吧?
    1to3
        10
    1to3  
       Dec 4, 2013 via Android   1
    db.blog.aggregate({$unwind: "$comments"}, {$sort: {comments.datetime: -1}})
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