How reflection works? Why serialization during reflection was removed in 0.21.1-next.2?

[gustawdaniel]

I asked question:

https://stackoverflow.com/questions/62233427/nexus-dev-command-runs-app-twice-how-to-fix-this-behavior

This is connected with commit:

graphql-nexus/nexus@ce1d453

@Weakky can you explain why you added these changes? I am interested in fixing this problem, but do not want to broke nothing from your code. Can I please for adding documentation of reflection in:

https://www.nexusjs.org/#/architecture?id=reflection

[gustawdaniel]

I modified code from my example to this:

import app from 'nexus'


const uid = require('uid')

let i = 0;

const sleep = async (ms: number) => {
    return new Promise((resolve, reject) => {
        setTimeout(resolve, ms)
    })
}

const recurrenceFunction = async (id: string): Promise<void> => {
    i++;
    console.log(xid, id, i, app.private.state.running);

    await sleep(2000);
    return recurrenceFunction(id)
}

const startQueue = () => {
    const id: string = uid();
    console.log("START",xid, id, app.private.state.running);
    return recurrenceFunction(id)
}

const xid = uid();
let limit=10;
const onApplicationStart = async (cb: () => any):Promise<any> => {
    console.log("can i start?", xid, limit, app.private.state.running);
    if(app.private.state.running) {
        await cb()
        return;
    }
    limit--;
    if(limit <= 0) return ;
    await sleep(100)
    return onApplicationStart(cb);
}

(async () => {

    return onApplicationStart(async () => {
        return startQueue()
    })

})()

It would be nice if handler on application start that is running single time would be added or documented.

[jasonkuhrt]

Eager module code relying on side-effects is not supported by Nexus.

See:

• https://www.nexusjs.org/#/tutorial/chapter-2-writing-your-first-schema?id=reflection
• custom input with create or connect field for relation child graphql-nexus/nexus#758

For a workaround for now wrap your code like this:

// app.ts
if (!process.env.NEXUS_REFLECTION) {
  yourHeavyAsyncCode()
}

Reference graphql-nexus/nexus#732 (comment)