Streaming Examples

[BeBoRE]

I find this to be a pretty interesting and promising project. Especially the streaming aspect of this. I am however failing to understand how to turn the result of toCrossJSONStream, back into an object on the other end. I already tried giving them separate refs and stuff. Maybe it would be handy if a few example projects are given to show-case how to make use of Seroval and it's streaming capabilities.

My current code:

import { toCrossJSONStream, fromCrossJSON } from "seroval";

const delay = <T>(delay : number, value : T) => new Promise<T>((resolve) => {
  setTimeout(() => resolve(value), delay)
})

const bla = {
  a: 'Hello',
  b: delay(1000, "World"),
  c: delay(2000, "Bla"),
  d: delay(3000, {
    e: 2500
  })
}

toCrossJSONStream(bla, {
  onParse(node, initial) {
      try {
        console.log(fromCrossJSON(node, {}))
      } catch (err : unknown) {
        if(err instanceof Error){
          console.log(err.cause)
        }
      }
  }
});

I get the errors:

$ node --experimental-strip-types index.ts
(node:37028) ExperimentalWarning: Type Stripping is an experimental feature and might change at any time
(Use `node --trace-warnings ...` to show where the warning was created)
{
  a: 'Hello',
  b: Promise { <pending> },
  c: Promise { <pending> },
  d: Promise { <pending> }
}
P [Error]: Missing "Promise" instance.
    at te.deserializePromiseResolve (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:12678)    
    at te.deserialize (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:14510)
    at ho (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:35797)
    at G.onParse [as onParseCallback] (file:///C:/Users/AfstOntw2/seroval/index.ts:21:21)
    at G.onParseInternal (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:31913)
    at G.onParse (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:32098)
    at G.handlePromiseSuccess (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:32993)
P [Error]: Missing "Promise" instance.
    at te.deserializePromiseResolve (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:12678)    
    at te.deserialize (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:14510)
    at ho (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:35797)
    at G.onParse [as onParseCallback] (file:///C:/Users/AfstOntw2/seroval/index.ts:21:21)
    at G.onParseInternal (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:31913)
    at G.onParse (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:32098)
    at G.handlePromiseSuccess (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:32993)
P [Error]: Missing "Promise" instance.
    at te.deserializePromiseResolve (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:12678)    
    at te.deserialize (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:14510)
    at ho (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:35797)
    at G.onParse [as onParseCallback] (file:///C:/Users/AfstOntw2/seroval/index.ts:21:21)
    at G.onParseInternal (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:31913)
    at G.onParse (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:32098)
    at G.handlePromiseSuccess (file:///C:/Users/AfstOntw2/seroval/node_modules/.pnpm/seroval@1.3.1/node_modules/seroval/dist/esm/production/index.mjs:17:32993)

[lxsmnsyc]

Thanks, might be an issue with the deserializer.

edit:
I just realized that you are missing that refs option for the fromCrossJSON which keeps track of object references across deserialization calls.

// Somewhere
const refs = new Map();

toCrossJSONStream(bla, {
  onParse(node, initial) {
    fromCrossJSON(node, { refs })
  },
  onDone() {
    refs.clear();
  },
});

[BeBoRE]

Yeah I tried adding refs to both, but that didn't fix the errors :/

[lxsmnsyc]

@BeBoRE please update Seroval since there's an issue with promise deserialization. But still, you need to the refs map in fromCrossJSON to map values correctly.

[BeBoRE]

Oh wait, I lied, after updating it does works! I was doing dumb stuff with the console log.

import { toCrossJSONStream, fromCrossJSON } from "seroval";

const delay = <T>(delay : number, value : T) => new Promise<T>((resolve) => {
  setTimeout(() => resolve(value), delay)
})

const bla = {
  a: 'Hello',
  b: delay(1000, "World"),
  c: delay(2000, "Bla"),
  d: delay(3000, {
    e: delay(4000, {
      f: "Foo"
    })
  })
}

const toCrossRefs = new Map();
const fromCrossRefs = new Map();

toCrossJSONStream(bla, {
  onParse(node, initial) {
      try {
        const result = fromCrossJSON<typeof bla>(node, { refs: fromCrossRefs });

        if (initial) {
          (async () => {
            console.log(result);
            console.log(await result.a);
            console.log(await result.b);
            console.log(await result.c);
            console.log(await result.d);
            console.log(await (await result.d).e);
          })()
        }
      } catch (err : unknown) {
        if(err instanceof Error){
          console.log(err.cause)
        }
      }
  },
  refs: toCrossRefs
});