通过id与mgo查找 [英] Find by id with mgo
问题描述
我想通过 _id
查找数据。我知道这个数据存在,并且存在这个 _id
(我用pymongo测试过它)。
但是下面的代码没有找到它:
type id_cookie struct {
IdCookie int
}
func get_id_mongo()int {
session,err:= mgo.Dial(127.0.0.1)
if err!= nil {
panic(err)
}
推迟session.Close()
//可选。将会话切换为单调行为。
session.SetMode(mgo.Monotonic,true)
c:= session.DB(id_bag)。C(id_cookie)
data:= id_cookie {} $ ($)
err2:= c.FindId(bson.M {_ id:bson.ObjectIdHex(58593d1d6aace357b32bb3a1)})。(& data)
if(err2!= nil){
Info.Println(error)
Info.Println(err2)
}
Info.Println(data)
返回data.IdCookie
}
它只是给我一个 0
。
但我可以使用pytmongo和python找到它。
导入请求
从pymongo导入pymongo
导入MongoClient
from bson.objectid import ObjectId
from pprint import pprint
client = MongoClient('127.0.0.1',27017)
导入base64
db = client.id_bag
pprint(db.collection_names())
result = db.id_cookie.insert_one(
{'IdCookie':1
})
print(result.inserted_id)
data = db.id_cook ie.find_one({_ id:ObjectId(58593d1d6aace357b32bb3a1)})
print(data)
这里是结果:
['id_cookie','system.indexes']
58593d2d6aace357b32bb3a3
{'IdCookie':1,'_id':ObjectId('58593d1d6aace357b32bb3a1')}
有没有人有任何想法?
编辑:
我试过:
err2:= c.FindId(bson.ObjectIdHex(58593d1d6aace357b32bb3a1))。(& data)
但我仍然有0:
信息:2016/12/20 15:42: 08 Cookie_Id.go:147:1
信息:2016/12/20 15:42:08 Cookie_Id.go:149:2
信息:2016/12/20 15:42:18 Cookie_Id.go :87:数据
信息:2016/12/20 15:42:18 Cookie_Id.go:88:{0}
信息:2016/12/20 15:42:18 Cookie_Id.go:89 :0
INFO:2016/12/20 15:42:18 Cookie_Id.go:118:0
INFO:2016/12/20 15:42:18 Cookie_Id.go:128:OK
您可以使用 Collection.FindId()
,然后只传递id值,或者使用 Collection.Find()
然后你必须指定一个字段名称的值:
err2:= c.FindId(bson.ObjectIdHex(58593d1d6aace357b32bb3a1))。(& data)
// OR
err2:= c.Find(bson.M {_ id:bson.ObjectIdHex(58593d1d6aace357b32bb3a1)})。
一个(&数据)
如果您没有错误,那意味着文档是找到。
如果您总是看到 0
打印出来(作为 id_cookie的值。 IdCookie
字段),这意味着持有此id的文档中的字段具有不同的名称。
使用建立标签,告诉它如何存储在你的MongoDB中。例如。如果在你的MongoDB中它被称为myid
,你可以像这样映射它:
type id_cookie struct {
IdCookie int`bson:myid`
}
还要注意,每次你想查询一些数据时,你不应该连接到MongoDB服务器,而应该连接一次,然后重新使用会话。有关详细信息,请参阅: mgo - 查询性能似乎一直很慢( 500-650ms)
I would like to find a data by _id
. I know that this data exists and that this _id
exist (I've tested it with pymongo).
But the code below doesn't find it:
type id_cookie struct {
IdCookie int
}
func get_id_mongo() int {
session, err := mgo.Dial("127.0.0.1")
if err != nil {
panic(err)
}
defer session.Close()
// Optional. Switch the session to a monotonic behavior.
session.SetMode(mgo.Monotonic, true)
c := session.DB("id_bag").C("id_cookie")
data := id_cookie{}
err2 := c.FindId(bson.M{"_id": bson.ObjectIdHex("58593d1d6aace357b32bb3a1")}).One(&data)
if (err2 != nil){
Info.Println("error")
Info.Println(err2)
}
Info.Println(data)
return data.IdCookie
}
It just returns me a 0
.
But I can find it using pytmongo and python.
import requests
import pymongo
from pymongo import MongoClient
from bson.objectid import ObjectId
from pprint import pprint
client = MongoClient('127.0.0.1', 27017)
import base64
db = client.id_bag
pprint(db.collection_names())
result = db.id_cookie.insert_one(
{ 'IdCookie': 1
})
print(result.inserted_id)
data = db.id_cookie.find_one({"_id": ObjectId("58593d1d6aace357b32bb3a1")})
print(data)
here are the result :
['id_cookie', 'system.indexes']
58593d2d6aace357b32bb3a3
{'IdCookie': 1, '_id': ObjectId('58593d1d6aace357b32bb3a1')}
Does anyone have any idea?
Edit : i've try with :
err2 := c.FindId(bson.ObjectIdHex("58593d1d6aace357b32bb3a1")).One(&data)
but i still have 0 :
INFO: 2016/12/20 15:42:08 Cookie_Id.go:147: 1
INFO: 2016/12/20 15:42:08 Cookie_Id.go:149: 2
INFO: 2016/12/20 15:42:18 Cookie_Id.go:87: data
INFO: 2016/12/20 15:42:18 Cookie_Id.go:88: {0}
INFO: 2016/12/20 15:42:18 Cookie_Id.go:89: 0
INFO: 2016/12/20 15:42:18 Cookie_Id.go:118: 0
INFO: 2016/12/20 15:42:18 Cookie_Id.go:128: OK
You either use Collection.FindId()
and then you pass only the id value, or you use Collection.Find()
and then you have to specify a value with the field name too:
err2 := c.FindId(bson.ObjectIdHex("58593d1d6aace357b32bb3a1")).One(&data)
// OR
err2 := c.Find(bson.M{"_id": bson.ObjectIdHex("58593d1d6aace357b32bb3a1")}).
One(&data)
If you get no errors, that means the document is found.
If you always see 0
printed (as the value of the id_cookie.IdCookie
field), that means the field in the document holding this id has a different name.
Use struct tags to tell how it is stored in your MongoDB. E.g. if in your MongoDB it is called "myid"
, you can map it like this:
type id_cookie struct {
IdCookie int `bson:"myid"`
}
Also note that you should not connect to the MongoDB server every time you want to query some data, instead connect once, and just reuse the session. for details see: mgo - query performance seems consistently slow (500-650ms)
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