duanduo0520 2019-01-26 13:19
浏览 50
已采纳

在golang中动态创建嵌套地图

I'm trying to interpret JSONs in Golang. I'm searching for a specific attribute in an unknown JSON which I know the keys for but my JSON might be really nested. I do know how many 'layers' there are in my JSON.

For example, if my JSON is:

nestedJson = { key1: { key2: { key3: "Found data" } } } 

my keys are ["key1", "key2", "key3"] and there are 3 layers in this JSON so I can get the data back out by doing

var nestedJson = []map[string]map[string]map[string]interface{}
json.Unmarshal([]byte(nestedJon), &nestedJson)
data := nestedJson["key1]["key2"]["key3"]

What I want to be able to do is dynamically create that nestedJson object by specifying an integer value for the number of layers is should search through.

Can anyone help with this? Please let me know if I haven't been clear enough!

  • 写回答

1条回答 默认 最新

  • douqi4673 2019-01-26 13:52
    关注

    In general, for cases like this you'll have to use the generic unmarshaling capability of json.Unmarshal into an interface{}.

    b := []byte(`{ "key1": { "key2": { "key3": "Found data" } } } `)
    var f interface{}
    if err := json.Unmarshal(b, &f); err != nil {
        panic(err)
    }
    fmt.Println(f)
    

    And now you can use a bunch of type assertions to explore f, for example to find which keys it contains:

    m := f.(map[string]interface{})
    for k, v := range m {
        if k == "key3" {
            fmt.Println("found key3. maps to", v)
        }
    }
    

    If you don't find key3 at this level, use recursion to check all the values - are they maps with key3 keys, and so on... Something like

    func findNested(m map[string]interface{}, s string) (bool, interface{}) {
        // Try to find key s at this level
        for k, v := range m {
            if k == s {
                return true, v
            }
        }
        // Not found on this level, so try to find it nested
        for _, v := range m {
            nm := v.(map[string]interface{})
            found, val := findNested(nm, s)
            if found {
                return found, val
            }
        }
        // Not found recursively
        return false, nil
    }
    

    Note: this function was quickly hacked together and probably mishandles a bunch of corner cases. It's here to demonstrate the key idea - use it as a basis for your specific needs

    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论

报告相同问题?

悬赏问题

  • ¥15 python天天向上类似问题,但没有清零
  • ¥30 3天&7天&&15天&销量如何统计同一行
  • ¥30 帮我写一段可以读取LD2450数据并计算距离的Arduino代码
  • ¥15 C#调用python代码(python带有库)
  • ¥15 矩阵加法的规则是两个矩阵中对应位置的数的绝对值进行加和
  • ¥15 活动选择题。最多可以参加几个项目?
  • ¥15 飞机曲面部件如机翼,壁板等具体的孔位模型
  • ¥15 vs2019中数据导出问题
  • ¥20 云服务Linux系统TCP-MSS值修改?
  • ¥20 关于#单片机#的问题:项目:使用模拟iic与ov2640通讯环境:F407问题:读取的ID号总是0xff,自己调了调发现在读从机数据时,SDA线上并未有信号变化(语言-c语言)