Go的范围不能超过< my var>(类型接口{}) [英] Go cannot range over <my var> (type interface {})

问题描述

我正处于起步阶段，试图将自己的想法笼罩在Go周围.目前，我正在模拟一个API请求，该请求返回一个包含对象数组的JSON格式的字符串.我正在尝试找出最合适的方法来遍历每个记录并访问每个字段.最终，每个字段都将写入Excel电子表格，但现在我只想打印每个字段的键&值.

I'm in the infant stages of trying to wrap my mind around Go. At the moment, I'm simulating an API request that returns a JSON-formatted string containing an array of objects. I'm trying to figure out the most appropriate way to iterate over each record and access each field. Ultimately, each field will be written to an Excel spreadsheet, but for now I just want to print each field's key & value.

这就是我所拥有的(我会在Go Playground中提供它，但不支持HTTP请求):

Here's what I have (I'd provide it in the Go Playground, but HTTP requests aren't supported):

    response, err := http.Get("http://go-proto.robwilkerson.org/demo.json")
    failOnError(err, "Uh oh")
    defer response.Body.Close()

    var view []interface{}
    json.NewDecoder(response.Body).Decode(&view)
    log.Printf(" [x] Pulled JSON: %s", view)
    for _, record := range view {
        log.Printf(" [===>] Record: %s", record)

        for key, val := range record {
            log.Printf(" [========>] %s = %s", key, val)
        }
    }

一切正常，直到尝试迭代保存每个记录属性的 map 的嵌套循环为止:

Everything works fine until the nested loop that attempts to iterate over the map that holds the properties of each record:

cannot range over record (type interface {})

我猜有两个问题:

1. 嵌套循环是访问每个记录的每个属性的最有效/最有效的方法吗?
2. 该如何解决该错误?

更新

当我将解码后的数据转储到 view 变量中时，这是记录的结果:

When I dump the data that is decoded into the view variable, this is the logged result:

[
    map[id:ef14912f-8031-42b3-8c50-7aa612287534 avatar:http://placehold.it/32x32 name:Vilma Hobbs email:[e-mail] phone:[phone] address:471 Dahill Road, Jacksonwald, Alabama, 6026] 
    map[id:1b7bf182-2482-4b8b-8210-9dc9ee51069e avatar:http://placehold.it/32x32 name:Anne Dalton email:[e-mail] phone:[phone] address:660 Macdougal Street, Ticonderoga, Alaska, 7942] 
    map[id:f8027852-f52e-4bbb-bc9d-fb5e34929b40 avatar:http://placehold.it/32x32 name:Amie Ray email:[e-mail] phone:[phone] address:878 Kane Street, Derwood, Minnesota, 3826] 
    map[id:b9842ab7-5053-48b4-a991-f5c63af8fb7e avatar:http://placehold.it/32x32 name:Hope Benton email:[e-mail] phone:[phone] address:396 Osborn Street, Rowe, Massachusetts, 702] 
    map[id:8f9f6d8d-d14e-4ddc-acb2-eb96d3c3d7a8 avatar:http://placehold.it/32x32 name:Janine Kidd email:[e-mail] phone:[phone] address:173 Manhattan Court, Hall, Virginia, 7376] 
    map[avatar:http://placehold.it/32x32 name:Kristen Yang email:[e-mail] phone:[phone] address:203 Doughty Street, Westmoreland, Rhode Island, 849 id:210a6ae6-8227-4f26-a47c-448c400f26e9] 
    map[name:Murray Sosa email:[e-mail] phone:[phone] address:811 Kingsland Avenue, Shepardsville, Hawaii, 9117 id:05f4f6af-19af-4b76-9aa8-9352281cf7d9 avatar:http://placehold.it/32x32] 
    map[phone:[phone] address:176 Underhill Avenue, Ebro, Washington, 8099 id:9d21268d-067c-4b16-a6cd-42d184c4c059 avatar:http://placehold.it/32x32 name:Paige Stanton email:[e-mail]] 
    map[id:9946c19f-c226-4ff3-b578-57a249f8d0c7 avatar:http://placehold.it/32x32 name:Melisa Oconnor email:[e-mail] phone:[phone] address:768 Wallabout Street, Cotopaxi, Florida, 3388] 
    map[id:ee0b82cb-4990-428b-ba36-088287a404ba avatar:http://placehold.it/32x32 name:Monique Poole email:[e-mail] phone:[phone] address:232 Hubbard Place, Islandia, Michigan, 3722]
]

推荐答案

未声明类型时json包将解码为的默认值是:

The defaults that the json package will decode into when the type isn't declared are:

bool, for JSON booleans
float64, for JSON numbers
string, for JSON strings
[]interface{}, for JSON arrays
map[string]interface{}, for JSON objects
nil for JSON null

由于每个 record (在您的示例中)都是一个json对象，因此您可以像下面这样声明每个对象为 map [string] interface {} :

Since each record is (in your example) a json object, you can assert each one as a map[string]interface{} like so:

for _, record := range view {
    log.Printf(" [===>] Record: %s", record)

    if rec, ok := record.(map[string]interface{}); ok {
        for key, val := range rec {
            log.Printf(" [========>] %s = %s", key, val)
        }
    } else {
        fmt.Printf("record not a map[string]interface{}: %v\n", record)
    }
}

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