I have to create a json of structure :

```
{
 "user_id":"1",
"program_id":"2",
"test_id":["1","2","3","4"],
"answers":["a","c","d","b"]
}

```

I am unable to pass array of strings, when I pass the array of string it goes like:-

```
{
 "user_id":"1",
"program_id":"2",
"test_id":"[1,2,3,4]",
"answers":"[a,c,d,b]"
}

```

Can someone guide me how to create a json with required structure above?