英文:
Using []struct with Json
问题
我正在尝试将JSON解析为[]struct，该JSON是从https://api.github.com/events获取的。然而，当我尝试访问数组中的每个struct时，出现错误：
类型GITHUB_EVENT不支持索引
我如何能够访问数组中的每个struct？
func httpGetEvents() {eventDataRAW := httpPageGet("https://api.github.com/events", true)eventDataJSON := new(GITHUB_EVENT)_ = json.Unmarshal([]byte(eventDataRAW), &eventDataJSON)fmt.Println(eventDataJSON[0].Id)}
type GITHUB_EVENT []struct {Id string `json:"id"`Type string `json:"type"`Actor struct {Id int `json:"id"`Login string `json:"login"`GravatarId string `json:"gravatar_id"`Url string `json:"url"`AvatarUrl string `json:"avatar_url"`} `json:"actor"`Repo struct {Id int `json:"id"`Name string `json:"name"`Url string `json:"url"`} `json:"repo"`Payload struct {PushId int `json:"push_id"`Size int `json:"size"`DistinctSize int `json:"distinct_size"`Ref string `json:"ref"`Head string `json:"head"`Before string `json:"before"`Commits []struct {Sha string `json:"sha"`Author struct {Email string `json:"email"`Name string `json:"name"`} `json:"author"`Message string `json:"message"`Distinct bool `json:"distinct"`Url string `json:"url"`} `json:"commits"`} `json:"payload"`Public bool `json:"public"`CreatedAt string `json:"created_at"`}
英文:
I'm trying to parse JSON to a []struct, the JSON is retrieved from https://api.github.com/events
However when I try to access each struct within the array I get an error:
type GITHUB_EVENT does not support indexing
How am I able to access each struct within the array?
func httpGetEvents() {eventDataRAW := httpPageGet("https://api.github.com/events", true)eventDataJSON := new(GITHUB_EVENT)_ = json.Unmarshal([]byte(eventDataRAW), &eventDataJSON)fmt.Println(eventDataJSON[0].Id)}//--------------------------------------------------------------------------------------//type GITHUB_EVENT []struct {Id string `json:"id"`Type string `json:"type"`Actor struct {Id int `json:"id"`Login string `json:"login"`GravatarId string `json:"gravatar_id"`Url string `json:"url"`AvatarUrl string `json:"avatar_url"`} `json:"actor"`Repo struct {Id int `json:"id"`Name string `json:"name"`Url string `json:"url"`} `json:"repo"`Payload struct {PushId int `json:"push_id"`Size int `json:"size"`DistinctSize int `json:"distinct_size"`Ref string `json:"ref"`Head string `json:"head"`Before string `json:"before"`Commits []struct {Sha string `json:"sha"`Author struct {Email string `json:"email"`Name string `json:"name"`} `json:"author"`Message string `json:"message"`Distinct bool `json:"distinct"`Url string `json:"url"`} `json:"commits"`} `json:"payload"`Public bool `json:"public"`CreatedAt string `json:"created_at"`}
答案1
得分: 1
这个语句：
eventDataJSON := new(GITHUB_EVENT)
声明了eventDataJSON为*GITHUB_EVENT（一个指向切片的指针），并将其初始化为nil指针。在解组后，你可以通过在索引之前显式解引用指针来访问第一个事件：
(*eventDataJSON)[0].Id
然而，更常规的方法是使用make：
eventDataJSON := make(GITHUB_EVENT, 0)
它将eventDataJSON声明为GITHUB_EVENT，并将其初始化为空切片。（记住，make用于特殊的内置类型，如切片、映射和通道）。
你可以将这个切片的指针传递给json.Unmarshal：
_ = json.Unmarshal([]byte(eventDataRAW), &eventDataJSON)
然后直接对切片进行索引：
fmt.Println(eventDataJSON[0].Id)
此外，json.Marshal会负责分配输出值，所以你可以声明eventDataJSON并跳过任何显式初始化：
var eventDataJSON GITHUB_EVENT
示例：http://play.golang.org/p/zaELDgnpB2
英文:
This statement:
eventDataJSON := new(GITHUB_EVENT)
declares eventDataJSON as *GITHUB_EVENT (a pointer to a slice), and initializes it as a nil pointer. After unmarshaling, you could access the first event by explicitly deref-ing the pointer before indexing:
(*eventDataJSON)[0].Id
However, the more conventional approach is to use make:
eventDataJSON := make(GITHUB_EVENT, 0)
which declares eventDataJSON as a GITHUB_EVENT, and initializes it as an empty slice. (Remember that make is for special built-in types such as slices, maps, and channels).
You could pass a pointer to this slice to json.Unmarshal:
_ = json.Unmarshal([]byte(eventDataRAW), &eventDataJSON)
...and then index the slice directly:
fmt.Println(eventDataJSON[0].Id)
Additionally, json.Marshal will take care of allocating the output value, so you could declare eventDataJSON and skip any explicit initialization:
var eventDataJSON GITHUB_EVENT
Example: http://play.golang.org/p/zaELDgnpB2
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