英文:
Golang - How do you decode json array and get the root property
问题
我无法解码这个Go中的JSON。映射返回nil。虽然Unmarshal可以从内存中工作，但最终我可能需要一个流。此外，我需要获取Foo、Bar和Baz键名。对此不太确定。
JSON:
{
"Foo" : {"Message" : "Hello World 1", "Count" : 1},
"Bar" : {"Message" : "Hello World 2", "Count" : 0},
"Baz" : {"Message" : "Hello World 3", "Count" : 1}
}
代码:
package main
import (
"encoding/json"
"fmt"
"os"
)
type Collection struct {
FooBar map[string]Data
}
type Data struct {
Message string `json:"Message"`
Count int `json:"Count"`
}
func main() {
//将会是http请求
file, err := os.Open("stream.json")
if err != nil {
panic(err)
}
decoder := json.NewDecoder(file)
var c Collection
err = decoder.Decode(&c)
if err != nil {
panic(err)
}
for key, value := range c.FooBar {
fmt.Println("Key:", key, "Value:", value)
}
//返回空映射
fmt.Println(c.FooBar)
}
英文:
I can't figure out how to decode this JSON in Go. The map returns nil. Unmarshal works from memory, but eventually I might need a stream. Also, I need to get Foo, Bar and Baz key names. Not sure about that one.
JSON:
{
"Foo" : {"Message" : "Hello World 1", "Count" : 1},
"Bar" : {"Message" : "Hello World 2", "Count" : 0},
"Baz" : {"Message" : "Hello World 3", "Count" : 1}
}
Code:
package main
import (
"encoding/json"
"fmt"
"os"
)
type Collection struct {
FooBar map[string]Data
}
type Data struct {
Message string `json:"Message"`
Count int `json:"Count"`
}
func main() {
//will be http
file, err := os.Open("stream.json")
if err != nil {
panic(err)
}
decoder := json.NewDecoder(file)
var c Collection
err = decoder.Decode(&c)
if err != nil {
panic(err)
}
for key, value := range c.FooBar {
fmt.Println("Key:", key, "Value:", value)
}
//returns empty map
fmt.Println(c.FooBar)
}
答案1
得分: 3
你不需要一个顶层的结构体，可以直接解码到一个map中：
err = decoder.Decode(&c.FooBar)
或者，直接移除结构体：
type Collection map[string]Data
对于你的顶层结构体，隐含的格式是：
{
"FooBar": {
"Foo" : {"Message" : "Hello World 1", "Count" : 1},
"Bar" : {"Message" : "Hello World 2", "Count" : 0},
"Baz" : {"Message" : "Hello World 3", "Count" : 1}
}
}
英文:
You don't need a top-level struct, decode directly into a map:
err = decoder.Decode(&c.FooBar)
Or, just remove the struct:
type Collection map[string]Data
With your top-level struct, the implied format is:
{
"FooBar": {
"Foo" : {"Message" : "Hello World 1", "Count" : 1},
"Bar" : {"Message" : "Hello World 2", "Count" : 0},
"Baz" : {"Message" : "Hello World 3", "Count" : 1}
}
}
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