General function to parse json string to kdb table?

Question

What would be the best way to parse the "result" of a JSON string in q and build a table out of its structure?

for example, if returned a json order book:

{
  "success":true,
  "message":"",
  "result":{
    "buy":[
      {"Quantity":19999,"Rate":0.73},
      {"Quantity":138877,"Rate":0.72}
    ],
    "sell":[
      {"Quantity":1999,"Rate":0.74},
      {"Quantity":7756,"Rate":0.75}
    ]
  }
}

what is a function that would convert this to:

x        Quantity  Rate
"buy"    19999     0.73
"buy"    138877    0.72
"sell"   1999      0.74
"sell"   7756      0.75

and work on arbitrary levels of nesting in the JSON?

score 3 · Accepted Answer · edited Nov 28 '17 at 16:28

3

Have you tried Arthur's implementation?

http://code.kx.com/q/cookbook/websockets/#json

Pretty straightforward.

q)\l json.k // get it from http://kx.com/q/e/json.k
q) // create some table t
q) .j.j t
q) .j.k .j.j t // recreate the json

edited Nov 28 '17 at 16:28

Thomas Smyth - Treliant

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answered Jul 21 '14 at 14:19

Manish Patel

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.j.k on the result gives `success`message`result!(1b;"";`Bid`Ask`Last!0.0000005 0.0000005 0.0000005), so getting what i need is trivial from here. thanks – nightTrevors Jul 23 '14 at 00:39
i am having issues with nested arrays like the one in my example. when i do .j.k on it, it gives a noupdate – nightTrevors Jul 23 '14 at 00:53
Are you doing this is a child thread+peach? Usually why you would get `noupdate` – Manish Patel Jul 23 '14 at 08:46

General function to parse json string to kdb table?

1 Answers1