次のようなデータを含むコレクションがあります。
{ "_id" : "279771168740729_161573583988659_462046", "user_likes" : false, "message" : "good morning ICICI Bank have a great day...waiting for today surprise", "like_count" : 0, "message_tags" : [ { "id" : "279771168740729", "name" : "ICICI Bank", "length" : 10, "offset" : 13, "type" : "page" } ], "page_username" : "icicibank", "page_id" : "279771168740729", "can_remove" : false, "from" : { "id" : "100002801855936", "name" : "Kowshik Krankz" }, "page_name" : "ICICI Bank", "post_id" : "279771168740729_161573583988659", "created_time" : "2012-11-03T04:10:31+0000" }
{ "_id" : "279771168740729_203743029752972", "icon" : "http://static.ak.fbcdn.net/rsrc.php/v2/yj/r/v2OnaTyTQZE.gif", "link" : "http://youtu.be/eKxIbLVRHRE", "page_username" : "icicibank", "caption" : "www.youtube.com", "from" : { "id" : "279771168740729", "category" : "Bank/financial institution", "name" : "ICICI Bank" }, "type" : "video", "updated_time" : "2012-07-18T04:32:24+0000", "shares" : { "count" : 40 }, "id" : "279771168740729_203743029752972", "message" : "Like Raghu, you too could be at the wrong place at the wrong time. But would you be able to clear your unpaid bills like Raghu did? Now you can! To know how, check out this video. For more details, visit http://bit.ly/NsoCY3", "picture" : "http://external.ak.fbcdn.net/safe_image.php?d=AQADR4-ELAVCbuSI&w=130&h=130&url=http%3A%2F%2Fi2.ytimg.com%2Fvi%2FeKxIbLVRHRE%2Fmqdefault.jpg", "source" : "http://www.youtube.com/v/eKxIbLVRHRE?version=3&autohide=1&autoplay=1", "status_type" : "shared_story", "likes" : { "count" : 643, "data" : [ { "id" : "100002247030669", "name" : "Angel Zoya" }, { "id" : "100002257585478", "name" : "Rakesh Kumar" }, { "id" : "100002062205767", "name" : "P.k. Choudhury" }, { "id" : "100000484071154", "name" : "Balaji Jadhvar" } ] }, "name" : "ICICI Bank", "page_id" : "279771168740729", "page_name" : "ICICI Bank", "created_time" : "2012-07-18T04:32:24+0000", "comments" : { "count" : 48 }, "actions" : [ { "link" : "http://www.facebook.com/279771168740729/posts/203743029752972", "name" : "Comment" }, { "link" : "http://www.facebook.com/279771168740729/posts/203743029752972", "name" : "Like" } ] }
{ "_id" : "279771168740729_203743029752972_572142", "user_likes" : false, "message" : ":-)", "like_count" : 4, "page_username" : "icicibank", "page_id" : "279771168740729", "can_remove" : false, "from" : { "id" : "1060073189", "name" : "Raja Bhowmik" }, "page_name" : "ICICI Bank", "post_id" : "279771168740729_203743029752972", "created_time" : "2012-07-18T04:33:57+0000" }
{ "_id" : "279771168740729_203743029752972_572155", "user_likes" : false, "message" : "@?", "like_count" : 4, "page_username" : "icicibank", "page_id" : "279771168740729", "can_remove" : false, "from" : { "id" : "100001965306815", "name" : "Akhil Pandit" }, "page_name" : "ICICI Bank", "post_id" : "279771168740729_203743029752972", "created_time" : "2012-07-18T04:39:55+0000" }
{ "_id" : "279771168740729_203743029752972_572157", "user_likes" : false, "message" : "This ad is in very bad taste given the timing of it's release and the passing away of Satwik in the Bannerghata forests in Bangalore. Maybe there is no relation, but the similarity of the situation is uncanny.", "like_count" : 4, "page_username" : "icicibank", "page_id" : "279771168740729", "can_remove" : false, "from" : { "id" : "588391958", "name" : "Vijay Alphonse" }, "page_name" : "ICICI Bank", "post_id" : "279771168740729_203743029752972", "created_time" : "2012-07-18T04:41:05+0000" }
{ "_id" : "279771168740729_203743029752972_572182", "user_likes" : false, "message" : "Lv 2 do job in a bank", "like_count" : 6, "page_username" : "icicibank", "page_id" : "279771168740729", "can_remove" : false, "from" : { "id" : "100002492179903", "name" : "Monica Chandwani" }, "page_name" : "ICICI Bank", "post_id" : "279771168740729_203743029752972", "created_time" : "2012-07-18T04:48:51+0000" }
{ "_id" : "279771168740729_203743029752972_572228", "user_likes" : false, "message" : "R u working in ici bnk", "like_count" : 4, "page_username" : "icicibank", "page_id" : "279771168740729", "can_remove" : false, "from" : { "id" : "100002412887446", "name" : "Brijesh Gaur" }, "page_name" : "ICICI Bank", "post_id" : "279771168740729_203743029752972", "created_time" : "2012-07-18T05:10:06+0000" }
ここでは、いいねの数 (like_count キーの値) に基づいて上位 2 つの投稿を表示する必要があります。したがって、ID 279771168740729_203743029752972_572182 の投稿が 1 番目 (count のように 6 が最大) になり、id 279771168740729_203743029752972_572142 が 2 番目 (4 が次に高い) というようになります。
私は2つのステップを思いつきました：
- likeCount と postId を発行する
- likeCount を降順に並べ替え、最初の 2 つのエントリを表示する
によると ：
var mapFunction = function() {
var likeCount = this.like_count;
var postId = this._id;
if(postId != null && likeCount != null){
emit(likeCount, postId);
}
};
var reduceFuntion = function(likeCount, postIdCollection) {
/*How to maintain a single sorted list of likeCount and show the corresponding post?*/
};
mongo db doc に従って、ソート機能についてすでに混乱しています。-この投稿を参照してください