[Recompose] Stream Props to React Children with RxJS

Posted 2020-10-18 Answer1215

You can decouple the parent stream Component from the mapped React Component by using props.children instead. This process involves mapping the stream to React’s cloneElement with the children then passing the props in manually.

 

We have the code below:

import React from "react"
import { render } from "react-dom"
import { Observable } from "rxjs"
import config from "recompose/rxjsObservableConfig"
import {
  setObservableConfig,
  componentFromStream,
  createEventHandler
} from "recompose"

setObservableConfig(config)

const Counter = ({ value, onInc, onDec }) => (
  <div>
    <button onClick={onInc}>+</button>
    <h2>{value}</h2>
    <button onClick={onDec}>-</button>
  </div>
)

const CounterStream = componentFromStream(
  props$ => {

    const { stream: onInc$, handler: onInc } = createEventHandler();
    const { stream: onDec$, handler: onDec } = createEventHandler();

    return props$
      .switchMap(
      propos => Observable.merge(
        onInc$.mapTo(1),
        onDec$.mapTo(-1)
      )
        .startWith(propos.value)
        .scan((acc, curr) => acc + curr)
        .map((value) => ({ value, onInc, onDec })))
      .map(
      Counter
      )
  }
);


const App = () => (
  <div>
    <CounterStream value={3} />
  </div>
)

render(<App />, document.getElementById("root"))

 

Now inside we use:

<CounterStream value={4} />

We want pass child into it:

const App = () => (
  <div>
    <CounterStream value={3}>
      <Counter />
    </CounterStream>
  </div>
)

 

So now, instead we map to Counter map in the JXS, we want to clone the child elemenet and pass down new props:

const CounterStream = componentFromStream(
  props$ => {

    const { stream: onInc$, handler: onInc } = createEventHandler();
    const { stream: onDec$, handler: onDec } = createEventHandler();

    return props$
      .switchMap(
      props => Observable.merge(
        onInc$.mapTo(1),
        onDec$.mapTo(-1)
      )
        .startWith(props.value)
        .scan((acc, curr) => acc + curr)
        .map((value) => ({ ...props, value, onInc, onDec }))
      ).map(props =>
        cloneElement(props.children, props)
      )
  }
);