getState for all action creators

[itrelease]

So suppose we create dispatcher with promise middleware:

import { createDispatcher, composeStores, createRedux } from 'redux';
import { Provider } from 'redux/react';
import * as stores from './stores/index';
import { thunkMiddleware, promiseMiddleware } from './middlewares';

const dispatcher = createDispatcher(
  composeStores(stores),
  getState => [promiseMiddleware, thunkMiddleware(getState)]
);
const redux = createRedux(dispatcher);

and we have some action:

function fetchTodoItem(todoItemId) {
  return {
    types: [FETCH_TODO_ITEM, FETCH_TODO_ITEM_OK, FETCH_TODO_ITEM_FAIL],
    promise: apiFetchTodoItem(todoItemId),
    todoItemId
  }
}

but in this action I want to check local state on presence this todo item to eliminate request, like this:

function fetchTodoItem(todoItemId, getState) {
  const { todos } = getState();

  if (todos[todoItemId]) {
    return;
  }

  return {
    types: [FETCH_TODO_ITEM, FETCH_TODO_ITEM_OK, FETCH_TODO_ITEM_FAIL],
    promise: apiFetchTodoItem(todoItemId),
    todoItemId
  }
}

The problem that I have no access to getState function.

One of the solutions is to pass to bindActionCreators optional argument getState function:

export default function bindActionCreators(actionCreators, dispatch, getState) {
 return mapValues(actionCreators, actionCreator =>
   (...args) => dispatch(actionCreator(...args, getState))
 );
}

so all actions can get state if they need it.

@gaearon @acdlite

[itrelease]

Or we can rewrite promise middleware like this:

export default function promiseMiddleware(getState) {
  return (next) => {
    const recurse = (action) => {
      if (typeof action === 'function') {
        return action(recurse, getState);
      }

      const { promise, types, ...rest } = action;

      if (!promise) {
        return next(action);
      }

      const [REQUEST, SUCCESS, FAILURE] = types;

      next({ ...rest, type: REQUEST });

      return promise.then(
        (result) => next({ ...rest, result, type: SUCCESS }),
        (error) => next({ ...rest, error, type: FAILURE })
      );
    };

    return recurse;
  };
}

and action will look something like this:

function fetchTodoItem(todoItemId) {
  return (dispatch, getState) => {
    const { todos } = getState();

    if (todos[todoItemId]) {
      return;
    }

    return dispatch({
      types: [FETCH_TODO_ITEM, FETCH_TODO_ITEM_OK, FETCH_TODO_ITEM_FAIL],
      promise: apiFetchTodoItem(todoItemId),
      todoItemId
    });
  };
}