golang断言：一个蛋疼的处理场景

发表于 更新于 分类于 ，

这一切都来源于一个蛋疼的需求场景处理：

因为历史原因，一个需要用到的JSON数据被整个缓存进Redis的一个key中，大概如下：

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127.0.0.1:6379> get dt
"{\"address\":[{\"duration\":90,\"format\":\"mp4\",\"url\":\"xxx.mp4\",\"ext\":\"{\\\"key\\\":\\\"val\\\"}\"},{\"duration\":90,\"format\":\"mp4\",\"url\":\"xxx.mp4\",\"ext\":\"{\\\"key\\\":\\\"val\\\"}\"}],\"value\":\"web\"}"
127.0.0.1:6379>

这里还是做了脱敏处理，实际的情形JSON的层级更深…
格式化显示的JSON结构大概是这样： 

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{
    "address": [
        {
            "duration": 90,
            "format": "mp4",
            "url": "xxx.mp4",
            "ext": "{\"key\":\"val\"}"
        },
        {
            "duration": 90,
            "format": "mp4",
            "url": "xxx.mp4",
            "ext": "{\"key\":\"val\"}"
        }
    ],
    "value": "web"
}

现在要做的是： address 里的每个元素的 url 字段需要更新。

现在知道的是：address 的值 是一个数组，数组的每个元素是一个map[string]interface{} 类型，map里的元素除了 “url”: “xxx.mp4”, 其他的数量不确定

实现代码大概如下（方便展示，省略了Redis读写的步骤）：

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detailByte := []byte(`{"address":[{"duration":90,"format":"mp4","url":"xxx.mp4","ext":"{\"key\":\"val\"}"},{"duration":90,"format":"mp4","url":"xxx.mp4","ext":"{\"key\":\"val\"}"}],"value":"web"}`)
detail := make(map[string]interface{}, 0)
json.Unmarshal(detailByte, &detail)
formatJson, _ := json.MarshalIndent(detail, "", "    ")
fmt.Println("before: ", string(formatJson))
if address, ok := detail["address"]; ok {
if item, ok2 := address.([]interface{}); ok2 {
for index, value := range item {
if vMap, ok3 := value.(map[string]interface{}); ok3 {
if _, ok4 := vMap["url"];ok4 {
vMap["url"] = "wtf.mp4"
}
item[index] = vMap
}
}
detail["address"] = item
}
}
formatJson, _ = json.MarshalIndent(detail, "", "    ")
fmt.Println("after: ", string(formatJson))

运行结果：

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before:  {
    "address": [
        {
            "duration": 90,
            "ext": "{\"key\":\"val\"}",
            "format": "mp4",
            "url": "xxx.mp4"
        },
        {
            "duration": 90,
            "ext": "{\"key\":\"val\"}",
            "format": "mp4",
            "url": "xxx.mp4"
        }
    ],
    "value": "web"
}
after:  {
    "address": [
        {
            "duration": 90,
            "ext": "{\"key\":\"val\"}",
            "format": "mp4",
            "url": "wtf.mp4"
        },
        {
            "duration": 90,
            "ext": "{\"key\":\"val\"}",
            "format": "mp4",
            "url": "wtf.mp4"
        }
    ],
    "value": "web"
}

怎么说呢，实现了感觉又没有真正实现…

哎，蛋疼。