golang无效操作：type interface {}不支持索引 [英] golang invalid operation: type interface {} does not support indexing

问题描述

我是golang的新手，在阅读嵌套的JSON响应时遇到问题。

I'm new to the golang and I have problem while reading the nested JSON response.

var d interface{}
json.NewDecoder(response.Body).Decode(&d)
test :=d["data"].(map[string]interface{})["type"]

response.Body 看起来像这样

{
    "links": {
      "self": "/domains/test.one"
    },
    "data": {
        "type": "domains",
        "id": "test.one",
        "attributes": {
            "product": " Website",
            "package": "Professional",
            "created_at": "2016-08-19T11:37:01Z"
        }
    }
}

我收到的错误是这样的：

The Error I'm getting is this:

invalid operation: d["data"] (type interface {} does not support indexing)

推荐答案

d 的类型是 interface {} ，所以你不能像 d [ data] ，你需要另一个类型断言：

d is of type interface{}, so you cannot index it like d["data"], you need another type assertion:

test := d.(map[string]interface{})["data"].(map[string]interface{})["type"]
fmt.Println(test)

然后它就会工作。输出将是域。请参阅 Go Playground 上的实例。

Then it will work. Output will be "domains". See a working example on the Go Playground.

还要注意，如果你声明 d 的类型为 map [string] interface {} ，那么你可以省去第一个类型断言：

Also note that if you declare d to be of type map[string]interface{}, you can spare the first type assertion:

var d map[string]interface{}
if err := json.NewDecoder(response.Body).Decode(&d); err != nil {
    panic(err)
}
test := d["data"].(map[string]interface{})["type"]
fmt.Println(test)

输出是一样的。试试去游乐场。

如果您需要多次执行这些操作和类似的操作，您可能会发现我的 github.com/icza/dyno 库有用（其主要目标是帮助使用动态对象）。

If you need to do these and similar operations many times, you may find my github.com/icza/dyno library useful (whose primary goal is to aid working with dynamic objects).

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