解组json时处理不同类型 [英] Handling different types when unmarshalling a json

问题描述

我正在使用一个端点(我不拥有并且无法修复)，并且该端点返回JSON.

I'm consuming an endpoint (which I don't own and I cannot fix) and this endpoint returns JSON.

问题在于此JSON可以采用不同的格式:

The problem is this JSON can come in different formats:

格式1:

{
  "message": "Message"
}

或

{
  "message": ["ERROR_CODE"]
}

取决于发生的事情.

我希望有一个结构来保存此响应，因此以后我可以检查message是字符串还是数组，并正确地遵循流程.

I'd like to have one struct to hold this response so later I can check if the message is a string or array, and properly follow a flow.

可以在Go中做到吗?我认为的第一种方法是具有两个结构，并尝试使用string解码为一个，如果发生错误，请尝试使用array解码为一个.

Is it possible to do it in Go? The first approach I thought was to have two structs and try to decode to the one with string, and if an error happens, try to decode to the one with array.

有没有更优雅的方法?

推荐答案

将其解组为interface{}类型的值，并使用类型断言或类型开关以检查类型价值最终.请注意，默认情况下，JSON数组未编组为[]interface{}类型的值，因此您必须检查该值以检测错误响应.

Unmarshal it into a value of interface{} type, and use a type assertion or type switch to inspect the type of value it ends up. Note that by default JSON arrays are unmarshaled into a value of type []interface{}, so you have to check for that to detect the error response.

例如:

type Response struct {
    Message interface{} `json:"message"`
}

func main() {
    inputs := []string{
        `{"message":"Message"}`,
        `{"message":["ERROR_CODE"]}`,
    }

    for _, input := range inputs {
        var r Response
        if err := json.Unmarshal([]byte(input), &r); err != nil {
            panic(err)
        }
        switch x := r.Message.(type) {
        case string:
            fmt.Println("Success, message:", x)
        case []interface{}:
            fmt.Println("Error, code:", x)
        default:
            fmt.Println("Something else:", x)
        }
    }
}

输出(在游乐场上尝试):

Success, message: Message
Error, code: [ERROR_CODE]

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