k6 SharedArray support json values?

Question

So im trying to load a .json file into a SharedArray according to the docs here: https://k6.io/docs/javascript-api/k6-data/sharedarray/

Right now my "load" function looks like this:

export function loadData(dataFile) {
  const data = new SharedArray('dataFile', function () {
    const obj = JSON.parse(open(dataFile));
    return obj; 
  })
  return data
}

Which I then load in my test file via:

const data = loadData("/resources/api/cloud-pos-check/cloud-post-check.json");
const body = data[0];

(data[0] above is the JSON object in the JSON file, it is the only object there in that .json file)

It was failing until I realized that what I am sending via the payload was a JavaScript Object/String and NOT actual JSON.

So I have to do JSON.stringify(body) for the payload. Which seems silly because I am opening a JSON file, parsing it to a string then re-converting it to JSON. I guess what I want to know is this necessary?

Can SharedArray HOLD an actual .json value? Or do I need to do what I am doing everytime I need to send an actual .json payload. FWIW If I try to read directly the object that open returns it shows as blank in the console.

Thanks

Answer 1

SharedArray can only store a single array (as the name implies). But nothing stops you from wrapping arbitrarily-complex objects or literals in a single-element array:

const shared = new SharedArray('dataFile', function () {
  const myobj = { "a":42, "nested": { "list": [ 1, 3, 3, 7 ] } };
  return [ myobj ]; 
});

And then access your object with shared[0]:

const myobj = shared[0];
console.log(myobj.nested.list[1]); // 3

For your specific use case:

export function loadData(dataFile) {
  const data = new SharedArray('dataFile', function() {
    return [ JSON.parse(open(dataFile)) ];
  })
  return data;
}

or even:

export function loadData(dataFile) {
  const data = new SharedArray('dataFile', function() {
    return [ JSON.parse(open(dataFile)) ];
  })
  return data[0];
}

Note that SharedArray instances can only be constructed in the init context.