一、概述

   有兩種方法可以查詢內(nèi)嵌文檔：查詢整個文檔蔓同；針對鍵值對進行查詢镶摘。這兩種方式是不同的悴务，下面我通過例子進行分別說明渴析。

二梭稚、查詢整個文檔

例如:有如下文檔

class GoalReportMongoModel(Document):

    id = StringField(primary_key=True)
    user_id = StringField()
    date = StringField()
    update_time = LongField()
    goals = ListField()
    leader_id = StringField()
    comment = StringField()
    checked = BooleanField()
    check_time = LongField()

參考示例：查詢date 為2016-08-05 user_id 為U06UGFL12
可以這樣查詢

db.getCollection("goal_report").find({date:'2016-08-05',user_id:'U06UGFL12'})

這種查詢會去精確匹配整個內(nèi)嵌文檔

三箱玷、鍵值對查詢

我們一般在查詢時怨规，不會去匹配整個內(nèi)嵌文檔，通常只針對內(nèi)嵌文檔的特定鍵值去查詢锡足。怎么做波丰？

答：查詢文檔時，可以使用"."來表示進入內(nèi)嵌文檔舶得。

參考實例：

 db.getCollection("goal_report").find({"goals.goal":'價值目標COO-1',"goals.assigner":'san.zhang'})

查詢結(jié)果

{ 
    "_id" : "U06UGFL12_2016-08-05", 
    "user_id" : "U06UGFL12", 
    "date" : "2016-08-05", 
    "update_time" : NumberLong(1470397732), 
    "goals" : [
        {
            "status" : "ensure", 
            "criterion_ok" : true, 
            "user_id" : "U06UGFL12", 
            "goal" : "價值目標COO-1", 
            "assigner" : "san.zhang", 
            "tool" : "", 
            "method_ok" : true, 
            "done_time" : NumberInt(0), 
            "method" : "", 
            "reason" : "本周",
            "criterion" : "", 
            "goal_type" : "valuable", 
            "expire_time" : NumberInt(0), 
            "execution" : NumberInt(2), 
            "id" : NumberInt(1135241564), 
            "planh" : ""
        }, 
       {
            "status" : "ensure", 
            "criterion_ok" : true, 
            "user_id" : "U06UGF232", 
            "goal" : "價值目標COO-2", 
            "assigner" : "san.zhang", 
            "tool" : "", 
            "method_ok" : true, 
            "done_time" : NumberInt(0), 
            "method" : "", 
            "reason" : "本周",
            "criterion" : "", 
            "goal_type" : "valuable", 
            "expire_time" : NumberInt(0), 
            "execution" : NumberInt(2), 
            "id" : NumberInt(1135241564), 
            "planh" : ""
        }, 

    ], 
    "leader_id" : "U08EC7FTM", 
    "checked" : true
}

四掰烟、數(shù)組里面包含內(nèi)嵌文檔的查詢

這種查詢相對來說比較復雜一點，所以內(nèi)嵌文檔的匹配也需要有些技巧沐批。例如下面的博客文檔中有一個commens:鍵用來保存別人的評論信息纫骑。

db.blog.insert({  
    "_id":"B001",  
    "title":"MongoDB查詢",  
    "comments":[  
      {"name":"ickes","score":3,"comment":"nice"},  
      {"name":"xl","score":4,"comment":"nice"},  
      {"name":"eksliang","score":5,"comment":"nice"},  
      {"name":"ickes","score":6,"comment":"nice"}  
    ]  
})  

現(xiàn)在要查詢由ickes評論的且5分以上文章

- 不能使用db.blog.find({"comments":{"name":"ickes","score":{"$gt":5}})去查，因為內(nèi)嵌文檔的匹配是精確匹配九孩，必須要匹配完整的文檔先馆，而這個查詢不會匹配comment鍵

-  不能使用db.blog.find({"comments":{"name":"ickes","score":{ '$gt' : 5},"comment":"nice"}})去查，還是那句話躺彬，文檔的匹配時精確匹配煤墙，這里使用了$gt作為范圍梅惯，所以也查不到

- 不能使用db.blog.find({"comments.name":"ickes","comments.score":{"$gt":5}})去查，前面講查詢條件的時候說過仿野，查詢條件里面的鍵值對會解釋為AND,但是對于數(shù)組的內(nèi)嵌文檔他會解釋為OR的關系铣减，也就是說上面實際是這樣的comments.name:ickes或者comments.score":{"$gt":5},這明顯不行嗎！（注意如果內(nèi)嵌文檔不在數(shù)組中脚作，還是AND葫哗，所以我才把這個拿出來單獨討論）

那對于數(shù)組里面的內(nèi)嵌文檔到底怎么辦？應該這么辦球涛，如下所示

這里需要使用"$elemMatch"操作符魄梯，僅當這種時候才使用這個操作符

db.blog.find({"comments":{  
    "$elemMatch":{"name":"ickes","score":{"$gt":5}}  
}})  

五、返回與查詢條件相匹配的任意一個數(shù)組元素

   我們可以使用"$slice"操作符進行數(shù)組元素返回限制宾符，但是當數(shù)組里面保存的是文檔的時候，我就想返回與我查詢條件相匹配的那個元素灭翔，其他的不要魏烫，怎么做？有技巧的哦肝箱！

文檔結(jié)構(gòu)如下：

db.blog.insert({  
    "_id":"B001",  
    "title":"MongoDB查詢",  
    "comments":[  
      {"name":"ickes","score":3,"comment":"nice"},  
      {"name":"xl","score":4,"comment":"nice"},  
      {"name":"eksliang","score":5,"comment":"nice"},  
      {"name":"ickes","score":6,"comment":"nice"}  
    ]  
})  

參考實例：

db.blog.find({"comments":{  
   "$elemMatch":{"name":"ickes","score":{"$gt":5}}}},  
   {"comments.$":1}--第二個參數(shù)是限制返回數(shù)據(jù)的哄褒，別看錯了，這是第二個參數(shù)  
)  

返回結(jié)果如下：僅返回與當前查詢條件相匹配的那個內(nèi)嵌文檔煌张。

{  
  "_id" : "B001",   
  "comments" : [ { "name" : "ickes", "score" : 6, "comment" : "nice" } ]   
}  

如果當前查詢有多個內(nèi)嵌文檔匹配呐赡，只會返回第一個

六、按照正則表達式查詢內(nèi)嵌文檔某個字段包含某個字符串

舉例：

{ 
    "_id" : "U08G7H48Y_2016-07-08", 
    "user_id" : "U08G7H48Y", 
    "date" : "2016-07-08", 
    "update_time" : NumberLong(1467978750), 
    "goals" : [
        {
            "status" : "unsure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "價值目標：確保IA項目組盈利指標達標", 
            "assigner" : "", 
            "tool" : "", 
            "method_ok" : true, 
            "id" : NumberInt(1363999581), 
            "done_time" : NumberInt(0), 
            "reason" : "短期目標不能確保：找不到更好的拿新用戶的方法", 
            "create_time" : NumberLong(1466508766869), 
            "criterion" : "確保每天收入達到5w骏融，力爭6w\nFollow：1w\nLike：1.5w\nTracker：0.5w\nPrivacy：1.5w\nMemoryBoost：1.5w", 
            "expire_time" : NumberInt(0), 
            "execution" : NumberInt(2), 
            "method" : "已經(jīng)入思維導圖链嘀。\n確保7月30日收入達到1.5w", 
            "planh" : ""
        }, 
        {
            "status" : "ensure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "價值目標：確保給組員制造W-W局面", 
            "assigner" : "", 
            "tool" : "Wunderlist", 
            "method_ok" : true, 
            "id" : NumberLong(2633899071), 
            "done_time" : NumberInt(0), 
            "reason" : "", 
            "create_time" : NumberLong(1465283369329), 
            "criterion" : "幫助管理者（李丁，時遷档玻，賈博怀泊，盧燕濤，孟友陽）盯住他的組員", 
            "expire_time" : NumberInt(0), 
            "execution" : NumberInt(1), 
            "method" : "確保增加項目負責人的管理組員能力：\n李丁每兩周跟我Review一下他的組員：需要設置李丁的ToDo\n時遷每兩周跟我Review一下他的組員：需要設置時遷的ToDo\n盧燕濤每兩周跟我Review一下他的組員：需要設置盧燕濤的ToDo\n孟友陽每周跟我Review一下他的組員：需要設置孟友陽的ToDo\n\n確保跟每個PM每個季度至少聊天一次: 已設置Review聊天記錄的todo", 
            "planh" : ""
        }, 
        {
            "status" : "unsure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "價值目標：確保PM可以流動起來", 
            "assigner" : "", 
            "tool" : "", 
            "method_ok" : true, 
            "id" : NumberInt(602193464), 
            "done_time" : NumberInt(0), 
            "reason" : "最近入職PM比較難误趴，感覺流動這個目標會看不住", 
            "create_time" : NumberLong(1465284005711), 
            "criterion" : "確保組內(nèi)PM新老搭配合理\n確保組內(nèi)新PM快速培訓", 
            "expire_time" : NumberInt(0), 
            "execution" : 1.5, 
            "method" : "確保7月底之前輸入兩個pm", 
            "planh" : ""
        }, 
        {
            "status" : "ensure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "價值目標：確保項目組流程完善", 
            "assigner" : "", 
            "tool" : "", 
            "method_ok" : true, 
            "id" : NumberInt(1616685108), 
            "done_time" : NumberInt(0), 
            "reason" : "", 
            "create_time" : NumberLong(1465284199829), 
            "criterion" : "確保項目組DEV流程完善", 
            "expire_time" : NumberInt(0), 
            "execution" : 1.5, 
            "method" : "確保項目組DEV流程完善", 
            "planh" : ""
        }, 
        {
            "status" : "unsure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "價值目標：確保項目組執(zhí)行力達到1X", 
            "assigner" : "", 
            "tool" : "", 
            "method_ok" : false, 
            "id" : NumberLong(4283629091), 
            "done_time" : NumberInt(0), 
            "reason" : "暫時沒有找到好的方法確保這個目標", 
            "create_time" : NumberLong(1465284143431), 
            "criterion" : "MB每周提交一個版本\nPM每周提交一個版本\niOS每兩完成一個Feature", 
            "expire_time" : NumberInt(0), 
            "execution" : NumberInt(2), 
            "method" : "每個單子Archive的時候要想一些是否需要rethink", 
            "planh" : ""
        }, 
        {
            "status" : "ensure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "價值目標：確保盯住競爭對手的程序", 
            "assigner" : "", 
            "tool" : "Wunderlist", 
            "method_ok" : true, 
            "id" : NumberLong(3852562557), 
            "done_time" : NumberInt(0), 
            "reason" : "", 
            "create_time" : NumberLong(1465283982245), 
            "criterion" : "確迸恚看榜單，Like凉当，Tracker等競品", 
            "expire_time" : NumberInt(0), 
            "execution" : 1.5, 
            "method" : "確保每", 
            "planh" : ""
        }, 
        {
            "status" : "ensure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "焦點目標", 
            "assigner" : "", 
            "tool" : "Wunderlist", 
            "method_ok" : true, 
            "id" : NumberInt(1973727620), 
            "done_time" : NumberInt(0), 
            "reason" : "", 
            "create_time" : NumberLong(1465284255588), 
            "criterion" : "確保關鍵字推廣在持續(xù)推進", 
            "expire_time" : NumberInt(1469808000), 
            "execution" : 1.5, 
            "method" : "推廣ROI", 
            "planh" : ""
        }, 
        {
            "status" : "unsure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "焦點目標：確保", 
            "assigner" : "", 
            "tool" : "", 
            "method_ok" : true, 
            "id" : NumberInt(123662851), 
            "done_time" : NumberInt(0), 
            "reason" : "這周上線的時候枣申。", 
            "create_time" : NumberLong(1465278975537), 
            "criterion" : "交叉", 
            "expire_time" : NumberInt(1467216000), 
            "execution" : NumberInt(2), 
            "method" : "詳見思維導圖", 
            "planh" : ""
        }, 
        {
            "status" : "ensure", 
            "user_id" : "U08G7H48Y", 
            "goal" : "焦點目標：確保跟進產(chǎn)品需求，多跟PM討論各種產(chǎn)品需求", 
            "assigner" : "", 
            "tool" : "", 
            "method_ok" : true, 
            "id" : NumberLong(3918152115), 
            "done_time" : NumberInt(0), 
            "reason" : "", 
            "create_time" : NumberLong(1467335980569), 
            "criterion" : "確保每天至少找一個PM討論需求15分鐘\n確保每次產(chǎn)品需求評審會都參加", 
            "expire_time" : NumberInt(0), 
            "execution" : NumberInt(2), 
            "method" : "每天至少找一個PM討論需求15分鐘看杭，已經(jīng)入todo\n", 
            "planh" : ""
        }
    ], 
    "leader_id" : "U06UGFL12", 
    "comment" : "個人產(chǎn)品能力和", 
    "check_time" : NumberLong(1468158420)
}

mongo 原生代碼查詢

db.getCollection("goal_report").find({"goals":{"$elemMatch":{"goal":{"$regex":/價值目標/}}}})

mongoengine 查詢

GoalReportMongoModel.objects(__raw__={"goals":{"$elemMatch":{"goal":{"$regex":'價值目標'}}}})

七忠藤、 查詢數(shù)組

數(shù)組元素模糊匹配

數(shù)組字段badges每個包含該元素black的文檔都將被返回

db.users.find({badges:"black"},{"_id":1,badges:1})
# 結(jié)果
        { "_id" : 1, "badges" : [ "blue", "black" ] }
        { "_id" : 4, "badges" : [ "red", "black" ] }
        { "_id" : 6, "badges" : [ "black", "blue" ] }

數(shù)組元素精確(全)匹配

數(shù)組字段badges的值為["black","blue"]的文檔才能被返回(數(shù)組元素值和元素順序全匹配)

 db.users.find({badges:["black","blue"]},{"_id":1,badges:1})
#結(jié)果
        { "_id" : 6, "badges" : [ "black", "blue" ] }

數(shù)組內(nèi)嵌文檔查詢

查詢數(shù)組points內(nèi)嵌文檔鍵points的值小于等于55的文檔，此處通過.成員的方式實現(xiàn)

db.users.find( { 'points.points': { $lte: 55}},{"_id":1,points:1})
# 結(jié)果
        { "_id" : 3, "points" : [ { "points" : 81, "bonus" : 8 }, { "points" : 55, "bonus" : 20 } ] }
        { "_id" : 4, "points" : [ { "points" : 53, "bonus" : 15 }, { "points" : 51, "bonus" : 15 } ] }