Unflatten from JSON problem

[pincpanter]

Hi all. I would like to extract the 'stdout' value from the following JSON string:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": [
       0,
       {
           "code": 0,
           "stdout": "{\"up\":true,\"pending\":false}}\n"
       }
   ]
}

This is a valid JSON string (checked with online validators), however I don't find a way to convert it to a LabVIEW cluster, probably because of the unnamed constant in the 'result' array.

This is what I tried:

Unflatten from JSON throws an error -375005: Type mismatch between JSON and LabVIEW.

Which is reasonable, because there is no 'unnamed' field. Honestly, I don't know what else to try.

[santo_13]

Oh wow, this is not a typical LV data structure, if you notice carefully, the "result" array is not of same type of elements, element 0 is numeric whereas element 1 is a dict.

You can use the https://www.vipm.io/package/jdp_science_jsontext/ to navigate to each element in that array and extract the value.

Which application conjured such an illogical data structure?

[cordm · Accepted solution]

The data structure is not representable in LabVIEW, but you can pick it apart using the path input.

JSONText also cannot handle the array as an array, although I am almost sure it could at one point in the past.

[pincpanter]

Thank you. Actually I tried with paths, but... in the wrong way. Honestly I did not realize that the "array" could contain heterogenous data, having in mind LabVIEW arrays.

[pincpanter]

---

@santo_13  ha scritto:
Oh wow, this is not a typical LV data structure, if you notice carefully, the "result" array is not of same type of elements, element 0 is numeric whereas element 1 is a dict.

You can use the https://www.vipm.io/package/jdp_science_jsontext/ to navigate to each element in that array and extract the value.

Which application conjured such an illogical data structure?

---

Thank for the answer. This is basically the output of a console application resident on a "smart" router, called via a json-rpc protocol. Actually I don't know what is the role of the 0 constant: I would think it's the return code of the command, but there is a seemingly more explicit "code" field.

[BertMcMahan]

---

@cordm wrote:

The data structure is not representable in LabVIEW, but you can pick it apart using the path input.

JSONText also cannot handle the array as an array, although I am almost sure it could at one point in the past.

---

 If you ask for the "Result" item and parse it into JSON array elements it works fine:

[cordm]

I misunderstood the JSONText documentation. What I thought was you could use an array of a cluster with all the expected data types and JSONText would automatically convert the array element to one of the data types, all other cluster elements having their default value. Might work, but very brittle and ambiguous.

So you can convert a JSON array with mixed types to a LabVIEW cluster. That way you lose the support for variable length input and have to go Berts route to keep it.

Here is a post on LAVA by JDP himself regarding this topic: https://lavag.org/topic/20236-cr-jsontext/page/7/#findComment-136699

> To handle mixed-type JSON Arrays, use a cluster with unnamed elements.