Mongodb 根據子文檔的某個特定欄位排序的問題

/* 1 */{    "_id" : ObjectId("55e542cd7f8b9aca2b8b4568"),    "game_id" : 1103,    "tags" : [         {            "tag_id" : 10,            "name" : "西遊",            "rank" : 10,        },         {            "tag_id" : 123,            "name" : "網遊",            "rank" : 1,        },     ],    "time_sort" : 1435306}/* 2 */{    "_id" : ObjectId("55dd8fe67f8b9a25528b64f7"),    "game_id" : 6408,    "tags" : [         {            "tag_id" : 28,            "name" : "白領最愛",            "rank" : 20,        },         {            "tag_id" : 123,            "name" : "網遊",            "rank" : 2,        },     ],    "time_sort" : 1411574}/* 3 */{    "_id" : ObjectId("55dd91197f8b9a25528b9585"),    "game_id" : 18498,    "tags" : [         {            "tag_id" : 19,            "name" : "回合制",            "pc_rank" : 120,        },         {            "tag_id" : 123,            "name" : "網遊",            "rank" : 3,        },     ],    "time_sort" : 1437385}

現在只想通過 網遊標籤的rank排序，語句應該怎麼寫

回複內容：

/* 1 */{    "_id" : ObjectId("55e542cd7f8b9aca2b8b4568"),    "game_id" : 1103,    "tags" : [         {            "tag_id" : 10,            "name" : "西遊",            "rank" : 10,        },         {            "tag_id" : 123,            "name" : "網遊",            "rank" : 1,        },     ],    "time_sort" : 1435306}/* 2 */{    "_id" : ObjectId("55dd8fe67f8b9a25528b64f7"),    "game_id" : 6408,    "tags" : [         {            "tag_id" : 28,            "name" : "白領最愛",            "rank" : 20,        },         {            "tag_id" : 123,            "name" : "網遊",            "rank" : 2,        },     ],    "time_sort" : 1411574}/* 3 */{    "_id" : ObjectId("55dd91197f8b9a25528b9585"),    "game_id" : 18498,    "tags" : [         {            "tag_id" : 19,            "name" : "回合制",            "pc_rank" : 120,        },         {            "tag_id" : 123,            "name" : "網遊",            "rank" : 3,        },     ],    "time_sort" : 1437385}

現在只想通過 網遊標籤的rank排序，語句應該怎麼寫

管道查詢然後用unwind打撒tags，再排序

"tags" : [         {            "tag_id" : 28,            "name" : "白領最愛",            "rank" : 20,        },         {            "tag_id" : 123,            "name" : "網遊",            "rank" : 2,        },     ],

tags數組裡面的兩個元素都有rank欄位，你要根據第一個rank排序還是第二個rank排序？

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