MongoDB更新文件

MongoDB · 發表 2019-03-03 07:00:39

摘要：本文命令都是在mongo shell下實戰的，到了真實的web專案中這些命令對應的實現都是有封裝的，所以不用被嚇到先貼上官方正統文件英文文件 ,下面的連結都是中文社群的 :joy: MongoDB更新文件的方法很多，尤...

本文命令都是在mongo shell下實戰的，到了真實的web專案中這些命令對應的實現都是有封裝的，所以不用被嚇到

先貼上官方正統文件 英文文件 ,下面的連結都是中文社群的 :joy:

MongoDB更新文件的方法很多，尤其是在3.2以後，主要的方法有以下幾種.

db.collection.updateOne() 即使可能有多個文件通過過濾條件匹配到，但是也最多也只更新一個文件。3.2 新版功能.

db.collection.updateMany() 更新所有通過過濾條件匹配到的文件.3.2 新版功能.

db.collection.replaceOne() 即使可能有多個文件通過過濾條件匹配到，但是也最多也只替換一個文件。3.2 新版功能.

db.collection.update() 即使可能有多個文件通過過濾條件匹配到，但是也最多也只更新或者替換一個文件。預設情況下只更新一個文件。要更新多個文件，請使用 multi 選項

db.collection.save() 通過傳入的文件來替換已有文件。

本文只對update()方法做說明，其餘幾個放發內建了連結可以去看官方文件

update()語法

db.collection.update(
<filter>,
<update>,
{
upsert: <boolean>,
writeConcern: <document>,
collation: <document>
}
)

引數說明：

query : update的查詢條件，類似sql update查詢內where條件。
update : update的物件和一些更新的操作符（如$set ,$inc ...）等，也可以理解為sql update查詢內set後面的
upsert : 可選，這個引數的意思是，如果不存在update的記錄，是否插入一條新的文件,true為插入，預設是false，不插入。
multi : 可選，mongodb 預設是false,只更新找到的第一條記錄，如果這個引數為true,就把按條件查出來多條記錄全部更新。
writeConcern :可選，丟擲異常的級別。

update過濾文件語法

1.相等查詢

{ <field1>: <value1>, <field2>: <value2>...}

表示式指定相等 條件,查詢滿足<field> 等於<value> 的所有文件，可以指定多組條件

2.查詢操作符來指定查詢條件

{ <field1>: { <operator1>: <value1> }, ... }

指定操作符查詢條件需要巢狀{},如查詢age欄位大於20的

{"age" : {$gt: 20}}

我們接著上一篇文章來測試，首先檢視users文件的記錄

> db.users.find().pretty()
{
"_id" : ObjectId("5c77461437955b945af7321f"),
"name" : "緣來是你",
"age" : 27,
"gender" : "male"
}
{
"_id" : ObjectId("5c77499137955b945af73220"),
"name" : "tom",
"age" : 22,
"gender" : "male"
}
{
"_id" : ObjectId("5c77499137955b945af73221"),
"name" : "Linda",
"age" : 18,
"gender" : "female"
}
{
"_id" : ObjectId("5c77731d37955b945af73222"),
"name" : "Hanmeimei",
"age" : 17,
"gender" : "female"
}
{
"_id" : ObjectId("5c7774b736397a1c0aa425ea"),
"name" : "Jack",
"age" : 42,
"gender" : "male"
}
{
"_id" : ObjectId("5c7774b736397a1c0aa425eb"),
"name" : "Lucy",
"age" : 23,
"gender" : "female"
}

pretty()方法可以在終端美化輸出結果

我們將tom的age改為20

> db.users.update({"name" : "tom"}, {$set : {"age" : 20}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find()
{ "_id" : ObjectId("5c77461437955b945af7321f"), "name" : "緣來是你", "age" : 27, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73220"), "name" : "tom", "age" : 20, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73221"), "name" : "Linda", "age" : 18, "gender" : "female" }
{ "_id" : ObjectId("5c77731d37955b945af73222"), "name" : "Hanmeimei", "age" : 17, "gender" : "female" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425ea"), "name" : "Jack", "age" : 42, "gender" : "male" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425eb"), "name" : "Lucy", "age" : 23, "gender" : "female" }

這裡就不用pretty()方法美化了，篇幅太長:joy:

看第二條文件，tom的年齡被改為了20

將Jack和Lucy的年齡改為25該怎麼做呢，先來個錯誤命令

> db.users.update({"name" : {$in : ["Jack", "Lucy"]}}, {$set: {"age" : 25}})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.users.find()
{ "_id" : ObjectId("5c77461437955b945af7321f"), "name" : "緣來是你", "age" : 27, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73220"), "name" : "tom", "age" : 20, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73221"), "name" : "Linda", "age" : 18, "gender" : "female" }
{ "_id" : ObjectId("5c77731d37955b945af73222"), "name" : "Hanmeimei", "age" : 17, "gender" : "female" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425ea"), "name" : "Jack", "age" : 25, "gender" : "male" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425eb"), "name" : "Lucy", "age" : 23, "gender" : "female" }

問題:只有Jack的年齡被更新為25而Lucy的沒有，前面說了update() 只更新匹配到的第一條記錄，要想更新多條需要設定multi 引數。來看下一條命令

> db.users.update({"name" : {$in : ["Jack", "Lucy"]}}, {$set: {"age" : 28}}, {multi : true})
WriteResult({ "nMatched" : 2, "nUpserted" : 0, "nModified" : 2 })
> db.users.find()
{ "_id" : ObjectId("5c77461437955b945af7321f"), "name" : "緣來是你", "age" : 27, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73220"), "name" : "tom", "age" : 20, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73221"), "name" : "Linda", "age" : 18, "gender" : "female" }
{ "_id" : ObjectId("5c77731d37955b945af73222"), "name" : "Hanmeimei", "age" : 17, "gender" : "female" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425ea"), "name" : "Jack", "age" : 28, "gender" : "male" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425eb"), "name" : "Lucy", "age" : 28, "gender" : "female" }

這裡加了{multi: true} 引數，所以Jack和Lucy的age都被設定成了28。如果更新的文件不存在呢？我們嘗試一下將upsert 設定為true，來看下一條命令

> db.users.update({"name":"Lucys"}, {$set : {"is_active": 0}}, {upsert: true})
WriteResult({
"nMatched" : 0,
"nUpserted" : 1,
"nModified" : 0,
"_id" : ObjectId("5c77946b96c95d22dfe8b411")
})
> db.users.find()
{ "_id" : ObjectId("5c77461437955b945af7321f"), "name" : "緣來是你", "age" : 27, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73220"), "name" : "tom", "age" : 20, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73221"), "name" : "Linda", "age" : 18, "gender" : "female" }
{ "_id" : ObjectId("5c77731d37955b945af73222"), "name" : "Hanmeimei", "age" : 17, "gender" : "female" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425ea"), "name" : "Jack", "age" : 28, "gender" : "male" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425eb"), "name" : "Lucy", "age" : 28, "gender" : "female" }
{ "_id" : ObjectId("5c77946b96c95d22dfe8b411"), "name" : "Lucys", "is_active" : 0 }

可以看到這裡mongodb新增了一條文件，而且除了_id 欄位外，其餘的欄位都出現在了更新語句中，沒出現的在文件中沒有.對於upsert 和multi 引數你也可以這麼設定

> db.users.update({"age": {$gt: 25}}, {$set: {"is_active": 1}}, false, true)
WriteResult({ "nMatched" : 3, "nUpserted" : 0, "nModified" : 3 })
> db.users.find()
{ "_id" : ObjectId("5c77461437955b945af7321f"), "name" : "緣來是你", "age" : 27, "gender" : "male", "is_active" : 1 }
{ "_id" : ObjectId("5c77499137955b945af73220"), "name" : "tom", "age" : 20, "gender" : "male" }
{ "_id" : ObjectId("5c77499137955b945af73221"), "name" : "Linda", "age" : 18, "gender" : "female" }
{ "_id" : ObjectId("5c77731d37955b945af73222"), "name" : "Hanmeimei", "age" : 17, "gender" : "female" }
{ "_id" : ObjectId("5c7774b736397a1c0aa425ea"), "name" : "Jack", "age" : 28, "gender" : "male", "is_active" : 1 }
{ "_id" : ObjectId("5c7774b736397a1c0aa425eb"), "name" : "Lucy", "age" : 28, "gender" : "female", "is_active" : 1 }
{ "_id" : ObjectId("5c77946b96c95d22dfe8b411"), "name" : "Lucys", "is_active" : 0 }

第一個引數false 是upsert 的值，第二個true 是multi 的值