英文:
Custom JSON mapping function in Go
问题
所以我正在制作一个调用restful API的Go服务，我无法控制我所调用的API。
我知道Go有一个很好的内置反序列化器NewDecoder->Decode，但它只适用于以大写字母开头的结构字段（即公共字段）。这会带来一个问题，因为我要消费的JSON看起来像这样：
{"_next": "someValue","data": [{/*一组对象*/}],"message": "success"}
我该如何映射"_next"这个字段？
英文:
So I'm making a Go service that makes a call to a restful API, I have no control over the API I'm calling.
I know that Go has a nice built in deserializer in NewDecoder->Decode, but it only works for struct fields that start with capital letters (aka public fields). Which poses a problem because the JSON I'm trying to consume looks like this:
{"_next": "someValue","data": [{/*a collection of objects*/}],"message": "success"}
How the heck would I map "_next"?
答案1
得分: 5
使用标签（tags）来指定JSON中的字段名。你上面发布的JSON对象可以像这样建模：
type Something struct {Next string `json:"_next"`Data []interface{} `json:"data"`Message string `json:"message"`}
进行测试：
func main() {var sg Somethingif err := json.Unmarshal([]byte(s), &sg); err != nil {panic(err)}fmt.Printf("%+v", sg)}
常量s的值为：
const s = `{"_next": "someValue","data": ["one", 2],"message": "success"}`
输出结果（在Go Playground上尝试）：
{Next:someValue Data:[one 2] Message:success}
还要注意，你也可以将JSON解组成map或interface{}值，这样你甚至不需要创建结构体，但是使用结构体会更方便：
func main() {var m map[string]interface{}if err := json.Unmarshal([]byte(s), &m); err != nil {panic(err)}fmt.Printf("%+v", m)}
常量s的值为：
const s = `{"_next": "someValue","data": ["one", 2],"message": "success"}`
输出结果（在Go Playground上尝试）：
map[_next:someValue data:[one 2] message:success]
只返回翻译好的部分，不要有别的内容。<details><summary>英文:</summary>Use [tags][1] to specify the field name in JSON. The JSON object you posted above can be modeled like this:type Something struct {Next string `json:"_next"`Data []interface{} `json:"data"`Message string `json:"message"`}Testing it:func main() {var sg Somethingif err := json.Unmarshal([]byte(s), &sg); err != nil {panic(err)}fmt.Printf("%+v", sg)}const s = `{"_next": "someValue","data": ["one", 2],"message": "success"}`Output (try it on the [Go Playground][2]):{Next:someValue Data:[one 2] Message:success}Also note that you may also unmarshal into maps or `interface{}` values, so you don't even have to create structs, but it won't be as convenient using it as the structs:func main() {var m map[string]interface{}if err := json.Unmarshal([]byte(s), &m); err != nil {panic(err)}fmt.Printf("%+v", m)}const s = `{"_next": "someValue","data": ["one", 2],"message": "success"}`Output (try it on the [Go Playground][3]):map[_next:someValue data:[one 2] message:success][1]: https://stackoverflow.com/questions/10858787/what-are-the-uses-for-tags-in-go/30889373#30889373[2]: https://play.golang.org/p/NJCkBpzdfn[3]: https://play.golang.org/p/cuKkKmlp5a</details># 答案2**得分**: 0标签将解决你的问题。希望这对其他来到这里的人有所帮助，你可以使用https://mholt.github.io/json-to-go/来生成Go结构体。将JSON结构粘贴到左侧，相应的Go类型将生成在右侧，你可以将其粘贴到你的程序中。<details><summary>英文:</summary>Tags will solve your problem.Hoping it may help others who come here, you can make use of https://mholt.github.io/json-to-go/ to generate Go structs. Paste a JSON structure on the left and the equivalent Go type will be generated to the right, which you can paste into your program.</details>
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