Response a JSON format string for Angular frontend to consume using GSON, Springboot

Question

Let say I have a JSON format string to provide as the response for Angular/AmChart to consume. How can I put and parse the response under SpringBoot2? I tried to put the sample response into a hashmap, but the postman shows that the JSON string did not append to the response.

Code goes here:

    @GetMapping("/candlestick")
    public HashMap<String, Object> getAllPlot(String json) { 

        HashMap<String, Object> map = new HashMap<>();

        json = json.substring(0, json.length() - 1);
        json = "[" + json+" whatever here";
        json = json + "]";

        map.put("data", json);

        return map;
    }

Postman result:

{
    "timestamp": "May 5, 2020 3:50:49 PM",
    "details": "uri=/api/candlestick"
}

Answer 1

Seems "String json" is null because there is no "@Param Sting json". if json not null it will be work