CODEWITHSUNDEEP
javascriptjsonpuredata
garrettlynchirl
garrettlynchirl

Reputation: 910

Javascript JSON parser in PureData

I'm trying to create a JSON script with retrieve, parse, and get functions as an object in PureData using the pdjs external. The pdjs external uses Google's V8 JavaScript engine. I'm able to parse built in JSON just fine, but not when it's JSON retrieved from the web. Where am I going wrong? Is my async function not correct?

Here is my code - both files should be in the same folder and pdjs should be installed in PureData.

Javascript (saved as (js-jsonparser.js'):

// Number of inlets and outlets for the Puredata object
inlets = 1;
outlets = 1;


// JSON object
const obj = {};

// To test
const json = JSON.parse('{"name":"John", "age":30, "city":"New York"}');


async function getjson(url)
{
    // Wait on the fetching of the JSON
    obj = await (await fetch(url).json());

    // Return the JSON object
    return obj;
}

function load()
{
    // Retrieve the passed url
    let url = arguments[0];

    // Define result variable
    let result;

    // if an argument was passed
    if (url)
    {
        // Call the getjson async function to retrieve the json
        let g = getjson(url);

        // Send 'retrieved' out the outlet
        g.then(result = "retrieved");
        g.then(outlet(0, result));

    }
    else
    {
        // Send 'error' out the outlet
        result = "error";
        outlet(0, result)
    }

    // to test via the pd window
    //post(result);
}

function get()
{
    // Send retrieved value out the outlet
    outlet(0, json.name); // this works with my 'built in' JSON
    outlet(0, obj.url); // this does not work with the retrieved JSON
}

Puredata patch (saved as jsonparser.pd):

#N canvas 427 166 1255 567 12;
#X declare -lib pdjs;
#X obj 264 180 l2s;
#X msg 296 136 compile;
#X text 351 134 recompile source;
#X obj 264 115 t a b;
#X obj 262 212 print;
#X msg 117 36 load https://api.nasa.gov/planetary/apod?api_key=DEMO_KEY&date=2024-06-06
;
#X msg 294 86 get url;
#X obj 504 -5 declare -lib pdjs;
#X obj 264 159 js js-jsonparser.js;
#X connect 0 0 4 0;
#X connect 1 0 8 0;
#X connect 3 0 8 0;
#X connect 3 1 1 0;
#X connect 5 0 3 0;
#X connect 6 0 3 0;
#X connect 8 0 0 0;

Upvotes: 0

Views: 51

Answers (1)

Asleepace
Asleepace

Reputation: 3745

The way you are calling .json() looks wrong, you should either do

obj = await (await fetch(url)).json();

or

obj = await fetch(url).then((res) => res.json())

Update: even better split this into two lines, and also make sure the request was succesful.

const response = await fetch(url)

if (!response.ok) {
   console.warn("request failed: ", response.status)
   return
}

const json = await response.json()

Upvotes: 1

Related Questions