goquest123 goquest123 - 3 months ago 14
JSON Question

golang Unmarshalling websocket-rails JSON response

[
[
"client_connected",
{
"id": null,
"channel": null,
"user_id": null,
"data": {
"connection_id": null
},
"success": null,
"result": null,
"server_token": null
}
]
]


Given this JSON response from a websocket-rails server, I was wondering what the best way to parse this as there is a string without any key?

Answer

This is not the best solution, but it is the simplest:

Since the JSON input is not the convenient key-value pairs (or arrays of that), we can't just use a simple struct (which would be desirable) to model the content.

Your JSON input is an array of arrays. Inside that there are mixed types, all which can be stored in the empty interface interface{} (which can hold a value of any type).

So you can represent your data structure with the type:

js := [][]interface{}{}

Here's the complete code to unmarshal it and print it:

js := [][]interface{}{}
err := json.Unmarshal([]byte(input), &js)
if err != nil {
    panic(err)
}
fmt.Printf("%q", js)

Output (wrapped):

[["client_connected" map["server_token":<nil> "id":<nil> "channel":<nil> 
  "user_id":<nil> "data":map["connection_id":<nil>] "success":<nil> "result":<nil>]]]

Try it on the Go Playground.

Notes:

Seemingly we could simplify it further by just using interface{} type for the js variable:

var js interface{}

And it works too, but in this case we would need Type assertions even to just get to the elements of the "wrapper" arrays which would be a step back.