Idea: Batching actions

[danielkcz]

What about being able to dispatch more actions at once? Currently the dispatch accepts single object as a result from action creator. Could it perhaps accept an array? It would then process all the actions sequentially before invoking change.

I've come to the situation in my editor app, that on press of a key I have to split the text (updating text of a current line), create a new line (with remaining text) and set focus on that new line. As of now I have this logic within single reducer, but that makes reducers rather complex and not really reusable. To keep a logic out off reducers, it means I would have to dispatch three consecutive actions. That means the re-render after each one. Perhaps I am worried too much and it might be just fine like that?

I guess that another option could be having a single action that would be basically processed by three different reducers, but I would have to basically call some external functions from reducer to provide necessary changes. Some other time I just want to update text of line or just create a new line. That would mean a different set of actions.

[ForbesLindesay]

That last option sounds best, it's generally best to fire actions that describe what happened (e.g. User typed character) rather than what mutations you want (e.g. Update text of line)

[quirinpa]

I'm using this middleware i made:

export default function nextMiddleware({ dispatch }) {
    return (next) => (action) => {

        let ret = next(action);
        const { then } = action;

        if (then) {
            let nextActions = then;
            if (!Array.isArray(nextActions))
                nextActions = [nextActions];

            nextActions.map(item => dispatch((typeof item === 'function') ? item(dispatch) : item));
        }
        return ret;
    };
}

it's available on my profile as a repo idk if it's updated though.

I use it to dispatch notifications when the user tries to login or register

[danielkcz]

@ForbesLindesay I guess you are right, but it means I would need merge result from all interested action creators. The ogic about "what is happening" have to be combined at the time of dispatch and then split again in reducers. It's kinda tied together and it would be also harder to examine such dispatch seeing data from all action creators there.

@quirinpa I haven't though about middleware, that might be good way to go. Thanks !

[taylorhakes]

@quirinpa You can't do it with just middleware. Each call to dispatch triggers all the subscribers.

You need a higher order store that wraps the dispatcher and only calls the subscribers once.

[quirinpa]

@FredyC No problem man :)
@taylorhakes It is working for me. My subscribers are getting fired fine (i think). I'm actually not using this currently but i use something similar:

const SUCCESS = 'SUCCESS';
const FAILURE = 'FAILURE';

function bindPayloadOrNext(type, status, then, dispatch) {
    return payload => {
        if (then) dispatch({ type, status, payload, then: then(payload) });
        else dispatch({type, status, payload});
    };
}

export default function clientMiddleware(client) {
    return ({ dispatch/*, getState */}) => {
        return (next) => (action) => {

            const { type, promise, onSuccess, onFailure, ...rest } = action;
            if (!promise) {
                return next(action);
            }

            // console.log('MIDDLEWARE CLIENT ', action.type);
            // console.log(action);

            next({type, ...rest});
            return promise(client).then(
                bindPayloadOrNext(type, SUCCESS, onSuccess, dispatch),
                bindPayloadOrNext(type, FAILURE, onFailure, dispatch)
            );
        };
    };
}

which is an adaptation of the ClientMiddlewareCreator from erikras' react-redux-universal-hot-example.

I use it in my login action:

import { LOGIN, REGISTER } from './';
import { notify } from './notes'; // this is my other action

export function login(username, password) {
    return {
        type: LOGIN,
        promise: (client) => client.post('/login', {
            data: {
                username: username,
                password: password
            }
        }),
        onSuccess: () => notify('Login successful!', 'ok'),
        onFailure: notify
    };
}

it seems to be working properly. What am i missing? cheers.

[taylorhakes]

The original question was about batching actions. He wanted to call a bunch of actions and then trigger the subscribers only after all the actions. Your code takes an array of actions and calls the dispatch for each action. It doesn't batch the actions (at least the way he originally wanted).

If you take a look at the dispatch function https://github.com/rackt/redux/blob/master/src/createStore.js#L92, you will see that your example code calls the subscribers multiple times (once for each action in the array), not just once.

[tappleby]

I wrote a higher order store store enhancer: redux-batched-subscribe which will allow you to debounce the calls to subscribe handlers so they only happen once for consecutive actions.

[quirinpa]

@taylorhakes You can use only one next action though, and if you set the "next" of that action, it basically "batches them" consecutively. Well, to each their own xD

[johanneslumpe]

@quirinpa But it misses the point of the question ;)

[taylorhakes]

@tappleby Very cool. That is the point I was trying to get across.

[quirinpa]

I honestly didn't even read the array part. TL;DR lol you redux people confuse me

[taylorhakes]

@quirinpa I apologize if any of my responses sounded hostile. I want you to feel like a redux person! The more community involvement the better. I was only trying to bring up a point about how redux works.

Everyone is relatively new at using redux (it's only a few months old) and is trying to figure out the best ways to develop with it. Most times there is no definitive right or wrong answer.

[mindjuice]

There is also redux-batched-updates from @acdlite.

[quirinpa]

@taylorhakes :) nah, not hostile. Ofc i appreciate your input most of the times i ask stuff in order to learn more, but i know how i can sound :P ur awesome and the community aswell :D, i still have a lot to learn but ofc i want to be a part of it. xD cheers! And thanks!

[danielkcz]

Thank you guys. I guess that the approach of @tappleby sounds the most useful for my case. My reducers are synchronous, so I can easily use setImmediate and have it to invoke subscribers after all the actions are processed.

Using batchedUpdates sounds not that useful for this case or perhaps I am missing a point.