如何在golang中定义此类型的数据

Question

I have a data like '{"{\"hello\":\"world\"}"}', it's a array json in postgresql.

I don't know how to handle it in golang. I know I can define with string then use json.Unmarshal to slove, but I want to know if there is a way to get it in a struct

Answer 1

I assume you posted incorrect JSON and let's say it's '{"hello": "world"} A struct has a predefined fields, and with arbitrary JSON coming in it's impossible to know ahead. The possible solution would be to convert it into a map.

var data interface{}
b := []byte(`{"hello": "world"}`)
err := json.Unmarshal(b, &data)
if err != nil {
        panic(err)
}
fmt.Print(data)

As you print out the data, you'll probably get something like. map[hello:world]

Which is in the form of map[string]interface{}.

Then you can use type switch to loop into the map structure until you type assert all the interface{}.

for k, v := range data.(map[string]interface{}) {
        switch val := v.(type) {
        case string:
                v = val
        default:
                fmt.Println(k, "is unknown type")
        }
}

Map is an ideal data structure when dealing with arbitrary incoming JSON. However, if the JSON is generated from an SQL table with predefined schemas, you can use a struct with the same structure instead of a map.

type Hello struct {
        Hello string `json:"hello"`
}