英文:
Empty properties when serializing MongoDB data in Go
问题
这可能是一个非常愚蠢的问题，但是在搜索了两个小时之后，我决定在这里提问。
我尝试学习Go，并编写了一个非常简单的“Hello World”应用程序，其中使用Mongo作为数据源。我可以正常连接，可以获取数据，并且对象的数量也是正确的。
问题是，我将数据映射到的对象的属性为空，尽管Mongo中有数据。
我在Mongo中有一个非常简单的集合，名为"stations"，大约有12k条记录，如下所示：
{ "_id" : ObjectId("563c8d56819c3c91076b7c13"), "nm" : "00000BE8" }
{ "_id" : ObjectId("563c8d57819c3c91076b7c1a"), "nm" : "00000C01" }
{ "_id" : ObjectId("563c8d58819c3c91076b7c1d"), "nm" : "00000C02" }
{ "_id" : ObjectId("563c8d58819c3c91076b7c1f"), "nm" : "00000C31" }
{ "_id" : ObjectId("563c8d5d819c3c91076b86c1"), "nm" : "000013E0" }
{ "_id" : ObjectId("563c8d5d819c3c91076b86c5"), "nm" : "0000110B" }
整个Go程序如下所示：
package main
import (
"log"
"gopkg.in/mgo.v2"
)
type StationConfig struct {
id string `bson:"_id,omitempty"`
name string `bson:"nm"`
}
func main() {
session, err := mgo.Dial("192.168.1.41")
if err != nil {
panic(err)
}
defer session.Close()
c := session.DB("metos").C("stations")
var stationConfigs []StationConfig
err = c.Find(nil).Limit(100).All(&stationConfigs)
if err != nil {
log.Fatal(err)
}
log.Printf("Found document: %+v\n", stationConfigs)
}
但是当我运行程序时，_id和nm的值没有分配给相应的结构体属性，我得到以下输出：
Found document: [{id: name:} {id: name:} {id: name:} {id: name:}
{id: name:} {id: name:} {id: name:} {id: name:} {id: name:}
{id: name:} {id: name:} {id: name:} {id: name:} {id: name:}
{id: name:} {id: name:} {id: name:} {id: name:} {id: name:}
{id: name:} {id: name:} {id: name:} ... 以此类推 ... ]
我漏掉了什么？
英文:
This might be a very silly problem, but after two hours of searching the net I am posting the question here.
I tried learning Go and have a very simple "Hello World" application, which uses Mongo for the data source. I can connect normally, I can fetch the data, and the count of objects turns out ok.
The problem is, the object I map data to has empty properties, although there is data in Mongo.
I have a very simple collection in mongo, called stations with ~12k records like these:
{ "_id" : ObjectId("563c8d56819c3c91076b7c13"), "nm" : "00000BE8" }
{ "_id" : ObjectId("563c8d57819c3c91076b7c1a"), "nm" : "00000C01" }
{ "_id" : ObjectId("563c8d58819c3c91076b7c1d"), "nm" : "00000C02" }
{ "_id" : ObjectId("563c8d58819c3c91076b7c1f"), "nm" : "00000C31" }
{ "_id" : ObjectId("563c8d5d819c3c91076b86c1"), "nm" : "000013E0" }
{ "_id" : ObjectId("563c8d5d819c3c91076b86c5"), "nm" : "0000110B" }
The entire Go program looks like this:
package main
import (
"log"
"gopkg.in/mgo.v2"
)
type StationConfig struct {
id string `bson:"_id,omitempty"`
name string `bson:"nm"`
}
func main() {
session, err := mgo.Dial("192.168.1.41")
if err != nil {
panic(err)
}
defer session.Close()
c := session.DB("metos").C("stations")
var stationConfigs []StationConfig
err = c.Find(nil).Limit(100).All(&stationConfigs)
if err != nil {
log.Fatal(err)
}
log.Printf("Found document: %+v\n", stationConfigs)
}
But when I run the program, the values of _id and nm are not assigned to the respective struct properties and I get the following output:
Found document: [{id: name:} {id: name:} {id: name:} {id: name:}
{id: name:} {id: name:} {id: name:} {id: name:} {id: name:}
{id: name:} {id: name:} {id: name:} {id: name:} {id: name:}
{id: name:} {id: name:} {id: name:} {id: name:} {id: name:}
{id: name:} {id: name:} {id: name:} ... and so on ... ]
What am I missing?
答案1
得分: 1
我不熟悉MongoDB Go API，但我认为你的结构字段应该是公开的，以便MongoDB API能够填充它们。
尝试将你的字段设置为公开，看看是否有效：
type StationConfig struct {
ID string `bson:"_id,omitempty"`
Name string `bson:"nm"`
}
英文:
I'm not familiar with the MongoDB Go API but I think your struct fields should be public in order for the MongoDB API to be able to populate them.
Try making your fields public and see if it works:
type StationConfig struct {
ID string `bson:"_id,omitempty"`
Name string `bson:"nm"`
}
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