英文:
Golang/mgo: How can I ask MongoDB to use current time in a field?
问题
我有一个与我正在使用的MongoDB集合的类型匹配的结构体：
type AppInstance struct {Id bson.ObjectId "_id,omitempty"Url stringPriority intLastSeen string}
我希望LastSeen字段保存与该特定应用程序的最后交互的时间。因此，该应用程序在设置当前时间（作为字符串）时会注册自己。
我想要的是Mongo在插入时动态地将自己的当前时间设置到该字段中，就像MySQL的NOW()函数一样。
我有这个辅助函数：
func mongoNow() bson.JavaScript {return bson.JavaScript{Code:"return (new Date()).ISODate('YYYY-MM-DD hh:mm:ss');"}}
我尝试了这个：
c := mongoSession.DB("myapp").C("instances")rand.Seed(time.Now().UnixNano())err := c.Insert(struct{Id, Serial, Priority, Url, LastSeen interface{}}{Id: bson.NewObjectId(),Url: getInformedHost() + ":" + getRunningPortString(),Priority: rand.Int(),LastSeen: mongoNow() })checkError(err, "Could not register on MongoDB server.", 3)
LastSeen字段被存储为脚本而不是被评估：
[_id] => MongoId Object ([$id] => 502d6f984eaead30a134fa10)[id] => MongoId Object ([$id] => 502d6f98aa443e0ffd000001)[priority] => 1694546828=> 127.0.0.1:8080[lastseen] => MongoCode Object ([code] => (new Date()).ISODate('YYYY-MM-DD hh:mm:ss')[scope] => Array ())
所以，我认为有两个问题：
首先，如何插入当前时间？
其次，如何获取一些JavaScript代码的评估结果而不是插入？
对第二个问题的答案可能足以回答第一个问题，但也可能不足够。
英文:
I have this struct that matches the types of a MongoDB collection I'm using:
type AppInstance struct {Id bson.ObjectId "_id,omitempty"Url stringPriority intLastSeen string}
I want the LastSeen field to hold the time of the last interaction with that particular app. So, the app registers itself setting current time (as a string).
What I would like is Mongo to dynamically set its own current time into that field when it inserts, just like MySQL's NOW() function would do.
I have this helper function:
func mongoNow() bson.JavaScript {return bson.JavaScript{Code:"return (new Date()).ISODate('YYYY-MM-DD hh:mm:ss');"}}
And I tried this:
c := mongoSession.DB("myapp").C("instances")rand.Seed(time.Now().UnixNano())err := c.Insert(struct{Id, Serial, Priority, Url, LastSeen interface{}}{Id: bson.NewObjectId(),Url: getInformedHost() + ":" + getRunningPortString(),Priority: rand.Int(),LastSeen: mongoNow() })checkError(err, "Could not register on MongoDB server.", 3)
the LastSeen field gets stored as a script instead of evaluated:
[_id] => MongoId Object ([$id] => 502d6f984eaead30a134fa10)[id] => MongoId Object ([$id] => 502d6f98aa443e0ffd000001)[priority] => 1694546828=> 127.0.0.1:8080[lastseen] => MongoCode Object ([code] => (new Date()).ISODate('YYYY-MM-DD hh:mm:ss')[scope] => Array ())
So, I think there are to questions:
First, how can I insert the current time?
Second, how can I get some javascript evaluated instead of inserted?
The answer to the second one could be enough to answer the first one, but it might as well not be.
答案1
得分: 44
不要将时间存储为字符串。mgo支持time.Time，它类似于Javascript中的Date对象：
type Event struct {Id bson.ObjectId "_id,omitempty"Which stringDate time.Time}
插入一个当前发生的事件：
e := Event{Which: "第一个事件",Date: time.Now(),}c.Insert(e)
英文:
Don't store time as string. mgo supports time.Time which is like a Date object in Javascript:
type Event struct {Id bson.ObjectId "_id,omitempty"Which stringDate time.Time}
Insert an event that happened now:
e := Event{Which: "first event",Date: time.Now(),}c.Insert(e)
答案2
得分: 5
在Mongo 2.6中，您可以使用$currentDate运算符来实现。
db.users.update( { _id: 1 }, {$currentDate: {lastModified: true,lastModifiedTS: { $type: "timestamp" }},$set: { status: "D" }})
英文:
In Mongo 2.6 you can do it natively with $currentDate operator.
db.users.update( { _id: 1 }, {$currentDate: {lastModified: true,lastModifiedTS: { $type: "timestamp" }},$set: { status: "D" }})
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