Connecting Sagas to external Input/Output

We saw that take Effects are resolved by waiting for actions to be dispatched to the Store. And that put Effects are resolved by dispatching the actions provided as argument.

When a Saga is started (either at startup or later dynamically), the middleware automatically connects its take/put to the store. The 2 Effects can be seen as a sort of Input/Output to the Saga.

redux-saga provides a way to run a Saga outside of the Redux middleware environment and connect it to a custom Input/Output.

import { runSaga, stdChannel } from 'redux-saga'

const emitter = new EventEmitter()
const channel = stdChannel()
emitter.on("action", channel.put)

const myIO = {
  // this will be used to orchestrate take and put Effects
  channel,
  // this will be used to resolve put Effects
  dispatch(output) {
    emitter.emit("action", output)
  },
  // this will be used to resolve select Effects
  getState() {
    return state
  }
}

runSaga(
  myIO,
  function* saga() { ... },
)

For more info, see the API docs, Channels, demo