MongoDB通過值匹配更新數組元素

Question

我有一個'位置'集合，我想用'united + states'替換'usa'。數據庫的當前狀態爲：

> db.locations.find({'country':'usa'}) 
{ "_id" : "boston", "country" : [ "usa" ], "server" : "", "ts" : 1369642586.077319, "type" : [ "city" ] } 
{ "_id" : "chicago", "country" : [ "usa" ], "server" : "", "ts" : 1369642589.226037, "type" : [ "city" ] } 
{ "_id" : "las+vegas", "country" : [ "usa" ], "server" : "", "ts" : 1369642591.688284, "type" : [ "city" ] } 
{ "_id" : "los+angeles", "country" : [ "usa" ], "server" : "", "ts" : 1369642601.672113, "type" : [ "city" ] } 
{ "_id" : "miami", "country" : [ "usa" ], "server" : "", "ts" : 1369642606.281971, "type" : [ "city" ] } 
{ "_id" : "new+york", "country" : [ "usa" ], "server" : "", "ts" : 1369642611.884712, "type" : [ "city" ] } 
{ "_id" : "portland", "country" : [ "usa" ], "server" : "", "ts" : 1369642615.59296, "type" : [ "city" ] } 
{ "_id" : "san+francisco", "country" : [ "usa" ], "server" : "2", "ts" : 1369642619.255885, "type" : [ "city" ] } 
{ "_id" : "san+jose", "country" : [ "usa" ], "server" : "", "ts" : 1369642622.74329, "type" : [ "city" ] } 
{ "_id" : "seattle", "country" : [ "usa" ], "server" : "", "ts" : 1369642625.195549, "type" : [ "city" ] } 
{ "_id" : "washington+dc", "country" : [ "usa" ], "server" : "", "ts" : 1369642628.37334, "type" : [ "city" ] } 
{ "_id" : "cleveland", "country" : [ "usa" ], "server" : "2", "ts" : 1369642634.523065, "type" : [ "city" ] } 
{ "_id" : "columbus", "country" : [ "usa" ], "server" : "2", "ts" : 1369642636.874618, "type" : [ "city" ] } 
{ "_id" : "dallas", "country" : [ "usa" ], "server" : "2", "ts" : 1369642639.080141, "type" : [ "city" ] } 
{ "_id" : "denver", "country" : [ "usa" ], "server" : "2", "ts" : 1369642642.236581, "type" : [ "city" ] } 
{ "_id" : "houston", "country" : [ "usa" ], "server" : "2", "ts" : 1369642644.783804, "type" : [ "city" ] } 
{ "_id" : "minneapolis", "country" : [ "usa" ], "server" : "2", "ts" : 1369642647.153817, "type" : [ "city" ] } 
{ "_id" : "nashville", "country" : [ "usa" ], "server" : "2", "ts" : 1369642650.497276, "type" : [ "city" ] } 
{ "_id" : "new+orleans", "country" : [ "usa" ], "server" : "2", "ts" : 1369642653.584663, "type" : [ "city" ] } 
{ "_id" : "philadelphia", "country" : [ "usa" ], "server" : "2", "ts" : 1369642656.524054, "type" : [ "city" ] } 

我跑到下面的MongoDB的查詢，它應該做的伎倆：

db.locations.update({'country':'usa'}, {'$set': {'country.$': 'united+states'}}, multi=true) 

不過，這並沒有達到預期的影響和集合文件仍然有「美國」而不是「統一+國家」。

Answer 1

它看起來像你有你的更新調用一個錯字，而不是嘗試以下：

db.locations.update({'country':'usa'}, {'$set': {'country.$': 'united+states'}}, {multi:true}) 

注：選擇現在{multi:true}而非multi=true（或只是true）

Answer 2

更新多個數組元素是不可能的，請在此回答MongoDB update multiple records of array，如果他們是正確的，可能是這會工作

db.locations.find().forEach(function(doc) { 
    do { 
     db.locations.update({'country' : 'usa'}, 
     { $set : {'country.$' : 'united states'}}, true); 
    } while(db.getPrevError().n != 0); 
});