Question

我有一个带有元数据的数组中的注释文本的注释集合。我喜欢评论文本数组中的分页。分页应该让我得到“前5”或“下5”。在具有良好性能的mongoDB中执行此操作的最佳方法是什么。

   { "_id" : ObjectId( "502c706ac2e6777781a593f6" ),
      "commentType":"loc",
      "commentList" : [ 
{ "commentText" : "HelloComment",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
{ "commentText" : "2222222",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
{ "commentText" : "3333333",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
{ "commentText" : "44444444",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
{ "commentText" : "5555555",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
{ "commentText" : "6666666",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
    { "commentText" : "777777",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
    { "commentText" : "888888",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
    { "commentText" : "6666666",
  "commentTS" : Date( 1345165636344 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fd182d92b2a87f780c6bbe8" ) } }, 
{ "commentText" : "999999",
  "commentTS" : Date( 1345165668809 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fdeb271de26fd298262bb84" ) } }, 
{ "commentText" : "HelloComment",
  "commentTS" : Date( 1345749858601 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fdeb271de26fd298262bb84" ) } }, 
{ "commentText" : "NewTestforcomments",
  "commentTS" : Date( 1345750020526 ),
  "commentLoc" : { "commentlat" : 0,
    "commentlong" : 0 },
  "userInfo" : { "$ref" : "userProfile",
    "$id" : ObjectId( "4fdeb271de26fd298262bb84" ) } } ],
   } }

感谢您的帮助。

Answer 1

您可以使用$slice：http://www.mongodb.org/display/DOCS/Retrieving+a+Subset+of+Fields#RetrievingaSubsetofFields-RetrievingaSubrangeofArrayElements

执行此操作

这里还有一个切片的js测试例子，有几个例子： https://github.com/mongodb/mongo/blob/master/jstests/slice1.js

因此，findOne与$slice相结合可能是最佳选择。

如果没有关于您正在使用的语言的更多信息，我认为这是我能走得最深的。

mongoDB数组分页

1 个答案: