解析具有多个值类型和任意数量键的 JSON

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英文:

Unmarshall JSON with multiple value types and arbitrary number of keys

问题

我正在尝试读取以下形式的JSON:

{
  string: int,
  string: string,
  string: MyStruct,
  string: MyStruct,
  ...
  string: MyStruct,
}

例如:

{
  "status": 200,
  "message": "一些很酷的文本",
  "coolKeyA": {
    "name": "尤达",
    "age": 900
   },
  "CoolKeyB": {
    "name": "马哈拉勒勒",
    "age": 895
   },
   "CoolKeyC": {
    "name": "王子",
    "age": 57
   },
}

期望的结果是获得一个map[string]MyStruct的映射。其中"CoolKeyX"键的数量是弹性的或任意的,但其他键是静态的,例如status和message。

由于JSON中的值是不同类型的,我尝试将它们解析到一个空的map[string]interface{}中。然后目标是循环遍历键,并提取感兴趣的键,并将map[string]interface{string: string, string: int}的键转换为MyStruct。

scaryAcceptAll := map[string]interface{}{}
if err = json.Unmarshal(byteArray, &scaryAcceptAll); err != nil { 
  log.Printf("error: %v", err)
  return err 
} 

for k,v := range scaryAcceptAll { 
  if (k == "val0" ) || (k == "val1") {
      continue
  }   
  desiredMap[k] = models.MyStruct{Name: v["name"], Age: v["age"]}
}

这给我带来了以下错误:NonIndexableOperand: invalid operation: cannot index v (variable of type interface{})

我知道解组JSON的基本思想是创建一个与JSON类似的结构体并使用它,但由于我不知道确切的键的数量或"CoolKey"键实际上是什么(因为它是一个包含哈希值"000ab8f26d"的字符串),所以我不知道该怎么做。我知道接口有点像一个万能类型,但我不确定如何从中提取我想要的数据。

英文:

I'm attempting to read a JSON with the following form

{
  string: int,
  string: string,
  string: MyStruct,
  string: MyStruct,
  ...
  string: MyStruct,
}

For example

{
  "status": 200,
  "message": "some cool text",
  "coolKeyA": {
    "name": "yoda",
    "age": 900
   },
  "CoolKeyB": {
    "name": "Mahalalel",
    "age": 895
   },
   "CoolKeyC": {
    "name": "Prince",
    "age": 57
   },
}

The desired outcome is to get a map of map[string]MyStruct. There are an elastic or arbitrary number of "CoolKeyX" keys but the other keys are static, e.g., status and message.

Since the values in the JSON are different types I tried to reach them in to a blank map[string]interface{}. Then the goal is to loop through the keys and pluck out they keys of interest and convert the keys of map[string]inferface{string: string, string: int} to MyStruct.

scaryAcceptAll := map[string]interface{}{}
  if err = json.Unmarshal(byteArray, &scaryAcceptAll); err != nil { 
    log.Printf("error: %v", err)
    return err 
  } 
  
  for k,v := range scaryAcceptAll { 
    if (k == "val0" ) || (k == "val1") {
        continue
    }   
    desiredMap[k] = models.MyStruct{Name: v["name"], Age: v["age"]}
  }

Which gives me the following error: NonIndexableOperand: invalid operation: cannot index v (variable of type interface{})

I know the basic idea of unmarshalling JSONs is to create a struct that looks like the json and use that but since I don't know the exact number of keys or what the "CoolKey" key really is (because it's a string containing a hash "000ab8f26d") I didn't know how. I know interfaces are sort of a catch all but then I'm not sure how to pull my desired data out of it.

答案1

得分: 1

一种方法是实现一个自定义的json.Unmarshaler

type Obj struct {
	Status   int
	Message  string
	CoolKeys map[string]Person
}

type Person struct {
	Name string
	Age  int
}
func (o *Obj) UnmarshalJSON(data []byte) error {
    // 首先,将对象反序列化为原始 JSON 的映射
	var m map[string]json.RawMessage
	if err := json.Unmarshal(data, &m); err != nil {
		return err
	}

    // 接下来,反序列化状态和消息字段,以及不属于“CoolKey”组的任何其他字段
	if err := json.Unmarshal(m["status"], &o.Status); err != nil {
		return err
	}
	delete(m, "status") // 确保从映射中删除该字段
	if err := json.Unmarshal(m["message"], &o.Message); err != nil {
		return err
	}
	delete(m, "message") // 确保从映射中删除该字段

    // 最后,反序列化映射的其余内容
	o.CoolKeys = make(map[string]Person)
	for k, v := range m {
		var p Person
		if err := json.Unmarshal(v, &p); err != nil {
			return err
		}
		o.CoolKeys[k] = p
	}
	return nil
}

https://go.dev/play/p/s4YCmve-pnz

英文:

One approach would be implement a custom json.Unmarshaler:

type Obj struct {
	Status   int
	Message  string
	CoolKeys map[string]Person
}

type Person struct {
	Name string
	Age  int
}
func (o *Obj) UnmarshalJSON(data []byte) error {
    // first, unmarshal the object into a map of raw json
	var m map[string]json.RawMessage
	if err := json.Unmarshal(data, &m); err != nil {
		return err
	}

    // next, unmarshal the status and message fields, and any
    // other fields that don't belong to the "CoolKey" group
	if err := json.Unmarshal(m["status"], &o.Status); err != nil {
		return err
	}
	delete(m, "status") // make sure to delete it from the map
	if err := json.Unmarshal(m["message"], &o.Message); err != nil {
		return err
	}
	delete(m, "message") // make sure to delete it from the map

    // finally, unmarshal the rest of the map's content
	o.CoolKeys = make(map[string]Person)
	for k, v := range m {
		var p Person
		if err := json.Unmarshal(v, &p); err != nil {
			return err
		}
		o.CoolKeys[k] = p
	}
	return nil
}

https://go.dev/play/p/s4YCmve-pnz

huangapple
  • 本文由 发表于 2022年3月18日 01:31:53
  • 转载请务必保留本文链接:https://go.coder-hub.com/71516691.html
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