redux-saga-requests

Redux-Saga addon to simplify handling of AJAX requests. It supports Axios and Fetch API, but different integrations could be added, as they are implemented in a plugin fashion.

Table of content

• Motivation
• Installation
• Usage
• Actions
• Reducers
• Interceptors
• FSA
• Promise middleware
• Usage with Fetch API
• Mocking
• Multiple drivers
• Examples

Motivation :arrow_up:

With redux-saga-requests, assuming you use axios you could refactor a code in the following way:

  import axios from 'axios';
- import { takeEvery, put, call } from 'redux-saga/effects';
+ import { createRequestInstance, watchRequests, requestsReducer } from 'redux-saga-requests';
+ import { createDriver } from 'redux-saga-requests-axios';

  const FETCH_BOOKS = 'FETCH_BOOKS';
- const FETCH_BOOKS_SUCCESS = 'FETCH_BOOKS_SUCCESS';
- const FETCH_BOOKS_ERROR = 'FETCH_BOOKS_ERROR';

- const fetchBooks = () => ({ type: FETCH_BOOKS });
- const fetchBooksSuccess = data => ({ type: FETCH_BOOKS_SUCCESS, data });
- const fetchBooksError = error => ({ type: FETCH_BOOKS_ERROR, error });
+ const fetchBooks = () => ({
+   type: FETCH_BOOKS,
+   request: {
+     url: '/books',
+     // you can put here other Axios config attributes, like method, data, headers etc.
+   },
+ });

- const defaultState = {
-   data: null,
-   pending: 0, // number of pending FETCH_BOOKS requests
-   error: null,
- };
-
- const booksReducer = (state = defaultState, action) => {
-   switch (action.type) {
-     case FETCH_BOOKS:
-       return { ...defaultState, pending: state.pending + 1 };
-     case FETCH_BOOKS_SUCCESS:
-       return { ...defaultState, data: action.data, pending: state.pending - 1 };
-     case FETCH_BOOKS_ERROR:
-       return { ...defaultState, error: action.error, pending: state.pending - 1 };
-     default:
-       return state;
-   }
- };
+ const booksReducer = requestsReducer({ actionType: FETCH_BOOKS });

- const fetchBooksApi = () => axios.get('/books');
-
- function* fetchBooksSaga() {
-   try {
-     const response = yield call(fetchBooksApi);
-     yield put(fetchBooksSuccess(response.data));
-   } catch (e) {
-     yield put(fetchBooksError(e));
-   }
- }
-
  function* rootSaga() {
-   yield takeEvery(FETCH_BOOKS, fetchBooksSaga);
+   yield createRequestInstance({ driver: createDriver(axios) });
+   yield watchRequests();
  }

With redux-saga-requests, you no longer need to define error and success actions to do things like error handling or showing loading spinners. You don't need to write requests related repetitive sagas and reducers either.

Here you can see the list of features this library provides:

• you define your AJAX requests as simple actions, like { type: FETCH_BOOKS, request: { url: '/books' } } and success, error (abort is also supported, see below) actions will be dispatched automatically for you
• success, error and abort functions, which add correct and consistent suffixes to your request action types (check low-level-reducers example to see how to use those functions in your reducers)
• requestsReducer higher order reducer, which takes requests related state management burden from your shoulders
• automatic request abort - when a saga is cancelled, a request made by it is automatically aborted and an abort action is dispatched (especially handy with takeLatest and race Redux-Saga effects)
• sending multiple requests in one action - { type: FETCH_BOOKS_AND_AUTHORS, request: [{ url: '/books' }, { url: '/authors}'] } will send two requests and wrap them in Promise.all
• flexibility - you can use "auto mode" watchRequests (see basic example), or lower level sendRequest (see advanced example), or... you could even access your request instance with getRequestInstance
• support for Axios and Fetch API - additional clients could be added, you could even write your own client integration as a driver (see ./packages/redux-saga-requests-axios/src/axios-driver.js for the example)
• mocking - mock driver, which use can use for test purposes or when you would like to integrate with API not yet implemented (and once API is finished, you could just change driver to Axios or Fetch and magicaly everything will work!)
• multiple driver support - for example you can use Axios for one part of your requests and Fetch Api for another part
• compatible with FSA, redux-act and redux-actions libraries (see redux-act example)
• simple to use with server side rendering - for example you could pass Axios instance to createRequestInstance and you don't need to worry that Axios interceptors would be shared across multiple requests
• onRequest, onSuccess, onError and onAbort interceptors, you can attach your sagas (or simple functions) to them to define a global behaviour for a given event type
• optional requestsPromiseMiddleware, which promisifies requests actions dispatch, so you can wait in your react components to get request response, the same way like you can do this with redux-thunk

Installation :arrow_up:

To install the package, just run:

$ yarn add redux-saga-requests

or...

$ npm install redux-saga-requests

or you can just use CDN: https://unpkg.com/redux-saga-requests.

Also, you need to install a driver:

• if you use Axios, install axios and redux-saga-requests-axios:

  $ yarn add axios redux-saga-requests-axios
  

  or...

  $ npm install axios redux-saga-requests-axios
  

  or CDN: https://unpkg.com/redux-saga-requests-axios.

• if you use Fetch API, install isomorphic-fetch (or a different Fetch polyfill) and redux-saga-requests-fetch:

  $ yarn add isomorphic-fetch redux-saga-requests-fetch
  

  or...

  $ npm install isomorphic-fetch redux-saga-requests-fetch
  

  or CDN: https://unpkg.com/redux-saga-requests-fetch.

Of course, because this is Redux-Saga addon, you also need to install Redux-Saga.

Usage :arrow_up:

For a basic usage, see Motivation paragraph.

watchRequests

As you probably guessed, the most job is done by watchRequests, which is like a manager to your request actions - it sends requests you define in your actions and dispatches success, error and abort actions, depending on the outcome. It can also automatically abort requests. Aborting requests is a very important, but often neglected topic. Lets say you have a paginated list and a user asked for 1st page, then 2nd and lets assume response for 1st one will come later. Or... lets say a private data are being fetched and before this request is finished a user logged out. You could introduce many race condition bugs like this, without even realizing - they won't happen on your local machine (without throthling in your browser), but they could happen on a production system, especially on a slow mobile internet, with a high latency. Because aborting is so important, you can pass a config to watchRequests to adjust, how different actions will be aborted. This config has following attributes:

• abortOn: string | string[] | action => boolean: allows you to define actions, on which requests should be aborted, has the same form which you can pass to redux-saga take effect, for example 'LOGOUT', ['LOGOUT'], action => action.type === 'LOGOUT', default is null
• takeLatest: boolean | action => boolean: if true, when a new request will be dispatched while a pending of the same type is still running, the previous one will be automatically aborted, default is true for GET requests and false for the rest ones
• getLastActionKey: action => string: a key generator to match actions of the same type, typically you won't need to adjust it, but it might come in handy when you want some actions with the same type to be treated as a different one, default is action => action.type.

So, for instance, you could do this:

yield watchRequests({
  takeLatest: false,
  abortOn: 'LOGOUT',
});

Above defines a global behaviour, but what if you want to have different settings for different actions? Just define takeLatest or abortOn in action meta, for example:

const fetchBooks = () => ({
  type: FETCH_BOOKS,
  request: {
    url: '/books',
  },
  meta: {
    takeLatest: false,
    abortOn: 'LOGOUT',
  },
});

Moreover, remember that watchRequests is a blocking effect, so if you have more sagas, use yield fork(watchRequests), or wrap it with something else in all:

import { all, takeLatest, put } from 'redux-saga/effects';
import { createRequestInstance, watchRequests, success } from 'redux-saga-requests';
import { createDriver } from 'redux-saga-requests-axios';

function* fetchBooksSuccessSaga() {
  yield put(addMessage('Books have been loaded');
}

function* rootSaga() {
  yield createRequestInstance({ driver: createDriver(axios) });
  yield all([
    // put it before other sagas which handle requests, otherwise watchRequests might miss some requests...
    // or your sagas might miss requests actions, like success
    watchRequests(),
    takeLatest(success('FETCH_BOOK'), fetchBooksSuccessSaga),
  ]);
}

Last, but not least, if for some reason you don't want your request action to be handled by watchRequests, you can use meta.runByWatcher: like:

const fetchBooks = () => ({
  type: FETCH_BOOKS,
  request: {
    url: '/books',
  },
  meta: {
    runByWatcher: false,
  },
});

sendRequest

Under the hood, watchRequests uses a lower level sendRequest. watchRequests should be flexible enough, so you won't need to worry about sendRequest, but it is useful to know about it, it is handy in Interceptors. Also, if you don't like the magic of watchRequests, you might use it everywhere, or... you could write your own watchRequests!. This is how it works:

import axios from 'axios';
import { takeLatest } from 'redux-saga/effects';
import { createRequestInstance, sendRequest } from 'redux-saga-requests';
import { createDriver } from 'redux-saga-requests-axios'; // or a different driver

const FETCH_BOOKS = 'FETCH_BOOKS';

const fetchBooks = () => ({
  type: FETCH_BOOKS,
  request: { url: '/books' },
});

function* rootSaga() {
  yield createRequestInstance({ driver: createDriver(axios) });
  yield takeLatest(FETCH_BOOKS, sendRequest);
}

Now, if /books request is pending and another fetchBooks action is triggered, the previous request will be aborted and FETCH_BOOKS_ABORT will be dispatched.

You could also use race effect:

import axios from 'axios';
import { call, race, take, takeLatest } from 'redux-saga/effects';
import { createRequestInstance, sendRequest } from 'redux-saga-requests';
import { createDriver } from 'redux-saga-requests-axios'; // or a different driver

const FETCH_BOOKS = 'FETCH_BOOKS';
const CANCEL_REQUEST = 'CANCEL_REQUEST';

const fetchBooks = () => ({
  type: FETCH_BOOKS,
  request: { url: '/books' },
});

const cancelRequest = () => ({ type: CANCEL_REQUEST });

function* fetchBookSaga(fetchBookAction) {
  yield race([
    call(sendRequest, fetchBookAction),
    take(CANCEL_REQUEST),
  ]);
}

function* rootSaga() {
  yield createRequestInstance({ driver: createDriver(axios) });
  yield takeLatest(FETCH_BOOKS, fetchBookSaga);
}

In above case, not only the last /books request could be successful, but also it could be aborted with cancelRequest action, as sendRequest would be aborted as it would lose with take(CANCEL_REQUEST) effect.

Of course, you can send requests directly also from your sagas:

function* fetchBookSaga() {
  const { response, error } = yield call(
    sendRequest,
    fetchBooks(),
    { dispatchRequestAction: true },
  );

  if (response) {
    // do sth with response
  } else {
    // do sth with error
  }
}

The key here is, that you need to pass { dispatchRequestAction: true } as second argument to sendRequest, so that fetchBooks action will be dispatched - usually it is already dispatched somewhere else (from your React components onClick for instance), but here not, so we must explicitely tell sendRequest to dispatch it. Also, setting dispatchRequestAction as true will set your request action meta runByWatcher as false, so if you happen to use watchRequests, you won't end up with duplicated requests.

getRequestInstance

Also, it is possible to get access to your request instance (like Axios) in your Saga:

import { getRequestInstance } from 'redux-saga-requests';

function* fetchBookSaga() {
  const requestInstance = yield getRequestInstance();
  /* now you can do whatever you want, for example, if u use axios:
  const response = yield call(requestInstance.get, '/some-url') */
}

You can do whatever you want with it, which gives you maximum flexibility. Typically it is useful in Interceptors, when you want to make some request directly, without using redux action - for redux action you would use sendRequest.

Actions :arrow_up:

No matter whether you use watchRequests or sendRequest, you only need to define request actions, which will trigger AJAX calls for you, as well as dispatch success, error or abort actions. Lets say you defined a following request action:

const deleteBook = id => ({
  type: 'DELETE_BOOK',
  request: {
    url: `/books/${id}`,
    method: 'delete'
  },
  meta: { // meta is optional, it will be added to success, error or abort action when defined
    id,
  },
});

With this request action, assuming id = 1, following actions will be dispatched, depending on the request outcome:

Successful response

{
  type: 'DELETE_BOOK_SUCCESS',
  data: 'a server response',
  meta: {
    id: 1, // got from request action meta
    requestAction: {
      type: 'DELETE_BOOK',
      request: {
        url: '/books/1',
        method: 'delete'
      },
      meta: {
        id: 1,
      },
    },
  },
}

Error response

{
  type: 'DELETE_BOOK_ERROR',
  error: 'a server error',
  meta: {
    id: 1, // got from request action meta
    requestAction: {
      type: 'DELETE_BOOK',
      request: {
        url: '/books/1',
        method: 'delete'
      },
      meta: {
        id: 1,
      },
    },
  },
}

Aborted request

{
  type: 'DELETE_BOOK_ABORT',
  meta: {
    id: 1, // got from request action meta
    requestAction: {
      type: 'DELETE_BOOK',
      request: {
        url: '/books/1',
        method: 'delete'
      },
      meta: {
        id: 1,
      },
    },
  },
}

Reducers :arrow_up:

Except for watchRequests and sendRequest, which can simplify your actions and sagas a lot, you can also use requestsReducer, a higher order reducer, which is responsible for a portion of your state related to a given request type. For a general idea how it works, see Motivation paragraph. This is just a minimal example, where with simple:

const reducer = requestsReducer({ actionType: `FETCH_SOMETHING` });

you already have a working reducer which will handle FETCH_SOMETHING, FETCH_SOMETHING_SUCCESS, FETCH_SOMETHING_ERROR and FETCH_SOMETHING_ABORT actions, updating a following state attributes for you:

• data: here a data from your API will be kept, updated after FETCH_SOMETHING_SUCCESS is dispatched, initially set to null (default) or [], depending on multiple config attribute (see below)
• error: initially null, updated to a HTTP error after FETCH_SOMETHING_ERROR is dispatched
• pending: number of pending FETCH_SOMETHING requests, initially 0, incremented by 1 for each FETCH_SOMETHING, and decremented by 1 for each of FETCH_SOMETHING_SUCCESS, FETCH_SOMETHING_ERROR, FETCH_SOMETHING_ABORT (implemeted as integer, not boolean due to possibility of multiple pending requests of the same type - for example in a sequence FETCH_SOMETHING, FETCH_SOMETHING, FETCH_SOMETHING_SUCCESS we would set pending to false, despite the fact 2nd FETCH_SOMETHING is still running, with integer pending will be set to 1, which for example allows you to easily write a selector like showSpinner = pending => pending > 0)

In order to be flexible, apart from actionType passed in requestsReducer config, optionally you can pass any of following attributes:

• multiple: boolean: default to false, change it to true if you want your not loaded data to be stored as [] instead of null
• getData: (state, action, config) => data: describes how to get data from action object, by default returns action.data or action.payload.data when action is FSA compliant
• updateData: (state, action, config) => data: optional, useful together with operations to overwrite getData default, see more information in operations
• getError: (state, action, config) => data: describes how to get error from action object, by default returns action.error or action.payload when action is FSA compliant
• onRequest: (state, action, config) => nextState: here you can adjust how requestReducers handles request actions
• onSuccess: (state, action, config) => nextState: here you can adjust how requestReducers handles success actions
• onError: (state, action, config) => nextState: here you can adjust how requestReducers handles error actions
• onAbort: (state, action, config) => nextState: here you can adjust how requestReducers handles abort actions
• resetOn: action => boolean or string[]: callback or array of action types on which reducer will reset its state to initial one, for instance ['LOGOUT'] or action => action.type === 'LOGOUT', [] by default
• operations: optional object which you can use to map write actions like update/delete to data update, which also adds pending state and errors for each defined operation, see more details below

For example:

const reducer = requestsReducer({ actionType: `FETCH_SOMETHING`, multiple: true });

which will keep your empty data as [], not null.

For inspiration how you could override any of those attributes, see default config source.

You might also want to adjust any configuration for all your requests reducers globally. Here is how you can do this:

import { createRequestsReducer } from 'redux-saga-requests';

const requestsReducer = createRequestsReducer({ multiple: true });

Now, instead of built-in requestsReducer, you can use your own one, and from now on all reducers will have multiple set as true by default.

If you need to have an additional state next to built-in state in requestsReducer, or additional actions you would like it to handle, you can pass an optional custom reducer as a 2nd pararameter to requestsReducer:

const activeReducer = (state = { active: false }, action) => {
  switch (action.type) {
    case `SET_ACTIVE`:
      return { ...state, active: true };
    case `SET_INACTIVE`:
      return { ...state, active: false };
    default:
      return state;
  }

const reducer = requestsReducer({ actionType }, activeReducer);

which effectively will merge activeReducer with requestsReducer, giving you initial state:

const state = {
  data: null,
  error: null,
  pending: 0,
  active: false,
};

Another big feature of reducers are operations. They allow you to add additional actions to update data, with extra information kept in state useful to render button spinners or error messages. For example, lets say you have following request actions:

const fetchBooks = () => ({
  type: 'FETCH_BOOKS',
  request: { url: '/books' },
})

const deleteAllBooks = () => ({
  type: 'DELETE_ALL_BOOKS',
  request: { url: '/books', method: 'delete' },
})

You can create a following reducer:

const booksReducer = requestsReducer({
  actionType: 'FETCH_BOOKS',
  multiple: true,
  operations: {
    DELETE_ALL_BOOKS: { updateData: (state, action) => [] } // or just (state, action) => []
  },
});

which will give you the following initial state:

{
  data: [],
  error: null,
  pending: 0,
  operations: {
    DELETE_ALL_BOOKS: {
      error: null,
      pending: 0,
    },
  },
};

Notice that operations structure resembles the one from config we just passed, giving you useful error and pending state per operation. You can use them for example to show spinner or to disable DELETE button or to show a request error. Also, after a successful delete operation, data will be set to [] as defined in updateData.

It is also good to know, that you can set updateData to false, which would disable data manipulation and such an operation would be responsible only for pending and error state. Moreover, you can set updateData as true, which is useful to avoid duplication, as often your server responses are the same for multiple operations. Setting to true will fallback to top level updateData defined in requestsReducer config, and if updateData is not defined, global getData will be used.

There is one more case to cover in operations. Imagine we need another action:

const deleteBook = id => ({
  type: 'DELETE_BOOK',
  request: { url: `/book/${id}`, method: 'delete' },
})

Now, lets say we have a view with multiple books on one page and we want to show independent spinners for each corresponding DELETE button. Can you see the problem? If we just add DELETE_BOOK operation like DELETE_ALL_BOOKS, pending counter would be aggregated and all buttons would spin. We need to divide DELETE_BOOK per id, here is how we can achieve this:

const deleteBook = id => ({
  type: 'DELETE_BOOK',
  request: { url: `/book/${id}`, method: 'delete' },
  meta: {
    id, // we will need this id in reducer
  },
})

const booksReducer = requestsReducer({
  actionType: 'FETCH_BOOKS',
  multiple: true,
  operations: {
    DELETE_ALL_BOOKS: (state, action) => []
    DELETE_BOOK: {
      updateData: (state, action) => state.data.filter(book => book.id !== action.meta.id),
      getRequestKey: requestAction => String(requestAction.meta.id), // you need to use string if id is an integer
    }
  }
});

which will give you the following initial state:

{
  data: [],
  error: null,
  pending: 0,
  operations: {
    DELETE_ALL_BOOKS: {
      error: null,
      pending: 0,
    },
    DELETE_BOOK: {},
  },
};

... and if a deleteBook with id 1 and 2 are running, state would be:

{
  data: [],
  error: null,
  pending: 0,
  operations: {
    DELETE_ALL_BOOKS: {
      error: null,
      pending: 0,
    },
    DELETE_BOOK: {
      1: {
        error: null,
        pending: 1,
      },
      2: {
        error: null,
        pending: 1,
      },
    },
  },
};

So, DELETE_BOOK state is one lever deeper, with state divided per id. Be careful though to always check whether object with a given id exists before reading pending or error state, even after successful response, as you will never see below state:

DELETE_BOOK: {
  1: {
    error: null,
    pending: 0,
  },
  2: {
    error: null,
    pending: 0,
  },
},

as instead of resetting pending to 0, a given object is just removed to release memory.

As you can see, you can use requestsReducer, which will handle requests related logic in a configurable way with any custom logic you need.

However, if requestsReducer seems too magical for you, this is totally fine, you can write your reducers in a standard way too, but you might consider using success, error and abort helpers, which can add proper suffixes for you:

import { success, error, abort } from 'redux-saga-requests';

const initialState = {
  data: null,
  fetching: false,
  error: false,
};

const FETCH_BOOKS = 'FETCH_BOOKS';

const booksReducer = (state = initialState, action) => {
  switch (action.type) {
    case FETCH_BOOKS:
      return { ...initialState, fetching: true };
    case success(FETCH_BOOKS):
      return {
        ...initialState,
        data: { ...action.data },
      };
    case error(FETCH_BOOKS):
      return { ...initialState, error: true };
    case abort(FETCH_BOOKS):
      return { ...initialState, fetching: false };
    default:
      return state;
  }
};

Interceptors :arrow_up:

You can add global handlers to onRequest, onSuccess, onError add onAbort, like so:

import { sendRequest, getRequestInstance } from 'redux-saga-requests';

function* onRequestSaga(request, action) {
  // do sth with you request, like add token to header, or dispatch some action etc.
  return request;
}

function* onSuccessSaga(response, action) {
  // do sth with the response, dispatch some action etc
  return response;
}

function* onErrorSaga(error, action) {
  // do sth here, like dispatch some action

  // you must return { error } in case you dont want to catch error
  // or { error: anotherError }
  // or { response: someRequestResponse } if you want to recover from error

  if (tokenExpired(error)) {
    // get driver instance, in our case Axios to make a request without Redux
    const requestInstance = yield getRequestInstance();

    try {
      // trying to get a new token
      const { data } = yield call(
        requestInstance.post,
        '/refreshToken',
      );

      saveNewToken(data.token); // for example to localStorage

      // we fire the same request again:
      // - with silent: true not to dispatch duplicated actions
      return yield call(sendRequest, action, { silent: true });

      /* above is a handy shortcut of doing
      const { response, error } = yield call(
        sendRequest,
        action,
        { silent: true },
      );

      if (response) {
        return { response };
      } else {
        return { error };
      } */
    } catch(e) {
      // we didnt manage to get a new token
      return { error: e }
    }
  }

  // not related token error, we pass it like nothing happened
  return { error };
}

function* onAbortSaga(action) {
  // do sth, for example an action dispatch
}

function* rootSaga() {
  yield createRequestInstance({
    driver: createDriver(axios),
    onRequest: onRequestSaga,
    onSuccess: onSuccessSaga,
    onError: onErrorSaga,
    onAbort: onAbortSaga,
  });
  yield watchRequest();
}

If you need to use sendRequest in an interceptor, be aware of an additional options you can pass to it:

  yield call(sendRequest, action, {
    silent: true,
    runOnRequest: false,
    runOnSuccess: false,
    runOnError: false,
    runOnAbort: false,
});

Generally, use silent if you don't want to dispatch actions for a given request. The rest options is to disable given interceptors for a given request. By default silent is false, which simply means that sendRequests will dispatch Redux actions. The rest is slightly more dynamic:

• if a request is sent by watchRequests or a sendRequests not from an interceptor, all interceptors will be run
• if you use sendRequest in onRequest interceptor, runOnRequest is set to false
• if you use sendRequest in onSuccess interceptor, runOnSuccess and runOnError are set to false
• if you use sendRequest in onError interceptor, runOnError is set to false
• if you use sendRequest in onAbort interceptor, runOnAbort is set to false

Those defaults are set to meet most use cases without the need to worry about disabling proper interceptors manually. For example, if you use sendRequest in onRequest interceptor, you might end up with inifinite loop when runOnRequest was true. If your use case vary though, you can always overwrite this behaviour by runOn... options.

FSA :arrow_up:

If you like your actions to be compatible with Flux Standard Action, that's totally fine, you can define your request actions like:

const fetchBooks = () => ({
  type: 'FETCH_BOOKS',
  payload: {
    request: {
      url: '/books',
    },
  },
  meta: { // optional
    someKey: 'someValue',
  },
});

Then, success, error and abort actions will also be FSA compliant. Moreover, requestsReducer will also correctly handle FSA actions. For details, see redux-act example.

Promise middleware :arrow_up:

One disadvantage of using sagas is that there is no way to dispatch an action which triggers a saga from React component and wait for this saga to complete. Because of this, integration with libraries like Formik are sometimes harder - for example you are forced to push some callbacks to Redux actions for a saga to execute later, which is not convenient. Thats why this library gives an optional requestsPromiseMiddleware:

import { createStore, applyMiddleware } from 'redux';
import createSagaMiddleware from 'redux-saga';
import { requestsPromiseMiddleware } from 'redux-saga-requests';

const sagaMiddleware = createSagaMiddleware();
const store = createStore(
  app,
  initialState,
  applyMiddleware(requestsPromiseMiddleware(), sagaMiddleware),
);

Now, lets say you defined an action:

const fetchBooks = () => ({
  type: FETCH_BOOKS,
  request: { url: '/books'},
  meta: {
    asPromise: true,
  },
});

You can dispatch the action from a component and wait for a response:

class Books extends Component {
  fetch = () => {
    this.props.fetchBooks().then(successAction => {
      // handle successful response
    }).catch(errorOrAbortAction => {
      // handle error or aborted request
    })
  }

  render() {
    // ...
  }
}

Also, you can pass an optional auto flag to requestsPromiseMiddleware:

requestsPromiseMiddleware({
  auto: true // if you with to promisify all request actions without explicit meta.asPromise true
})

Note auto mode true will NOT promisify action with explicit meta.asPromise: false.

Usage with Fetch API :arrow_up:

All of the above examples show Axios usage, in order to use Fetch API, use below snippet:

import 'isomorphic-fetch'; // or a different fetch polyfill
import { createRequestInstance, watchRequests } from 'redux-saga-requests';
import { createDriver } from 'redux-saga-requests-fetch';

function* rootSaga() {
  yield createRequestInstance({
    driver: createDriver(
      window.fetch,
      {
        baseURL: 'https://my-domain.com' // optional - it works like axios baseURL, prepending all relative urls
        AbortController: window.AbortController, // optional, if your browser supports AbortController or you use a polyfill like https://github.com/mo/abortcontroller-polyfill
      }
    ),
  });
  yield watchRequests();
}

And in order to create Fetch API requests, below:

fetch('/users', {
  method: 'POST',
  body: JSON.stringify(data),
  headers: {
    'Content-Type': 'application/json',
  },
});

should be translated to this:

const fetchUsers = () => ({
  type: 'FETCH_USERS',
  request: {
    url: '/users/',
    method: 'POST',
    body: JSON.stringify(data),
    headers: {
      'Content-Type': 'application/json',
    },
  }
});

The point is, you can use the same request config like you do with pure Fetch API, but you need to pass url in the config itself. Also, one additional parameter you could provide in the config is responseType, which is set as json as the default. Available response types are: 'arraybuffer', 'blob', 'formData', 'json', 'text', or null (if you don't want a response stream to be read for the given response).

Also, this driver reads response streams automatically for you (depending on responseType you choose) and sets it as response.data, so instead of doing response.json(), just read response.data.

Mocking :arrow_up:

Probably you are sometimes in a situation when you would like to start working on a feature which needs some integration with an API. What you can do then? Probably you just wait or start writing some prototype which then you will polish once API is finished. You can do better with redux-saga-requests-mock, especially with multi driver support, which you can read about in the next paragraph. With this driver, you can define expected responses and errors which you would get from server and write your app normally. Then, after API is finished, you will just need to replace the driver with a real one, like Axios or Fetch API, without any additional refactoring necessary, which could save you a lot of time!

You can use it like this:

import { createRequestInstance, watchRequests } from 'redux-saga-requests';
import { createDriver } from 'redux-saga-requests-mock';

const FETCH_PHOTO = 'FETCH_PHOTO';

const fetchPhoto = id => ({
  type: FETCH_PHOTO,
  request: { url: `/photos/${id}` },
});

function* rootSaga() {
  yield createRequestInstance({
    driver: createDriver(
      {
        [FETCH_PHOTO]: (requestConfig, requestAction) => {
          // mock normal response for id 1 and 404 error fot the rest
          const id = requestConfig.url.split('/')[2];

          if (id === '1') {
            return {
              data: {
                albumId: 1,
                id: 1,
                title: 'accusamus beatae ad facilis cum similique qui sunt',
              },
            };
          }

          throw { status: 404 };
        },
      },
      {
        timeout: 1000, // optional, in ms, defining how much time mock request would take, useful for testing spinners
        getDataFromResponse: response => response.data // optional, if you mock Axios or Fetch API, you dont need to worry about it
      },
    ),
  });
  yield watchRequests();
}

Multiple drivers :arrow_up:

You can use multiple drivers if you need it. For example, if you want to use Axios by default, but also Fetch API sometimes, you can do it like this:

import axios from 'axios';
import 'isomorphic-fetch';
import { createRequestInstance, watchRequests } from 'redux-saga-requests';
import { createDriver as createAxiosDriver } from 'redux-saga-requests-axios';
import { createDriver as createFetchDriver } from 'redux-saga-requests-fetch';

function* rootSaga() {
  yield createRequestInstance({
    driver: {
      default: createAxiosDriver(axios),
      fetch: createFetchDriver(
        window.fetch,
        {
          baseURL: 'https://my-domain.com',
          AbortController: window.AbortController,
        },
      ),
    },
  });
  yield watchRequests();
}

As you can see, the default driver is Axios, so how to mark a request to be run by Fetch driver? Just pass the key you assigned Fetch driver to (fetch in our case) in action.meta.driver, for instance:

const fetchUsers = () => ({
  type: 'FETCH_USERS',
  request: {
    url: '/users/',
    method: 'POST',
    body: JSON.stringify(data),
    headers: {
      'Content-Type': 'application/json',
    },
  },
  meta: {
    driver: 'fetch',
  },
});

Also, if you want to use getRequestInstance with Fetch driver, just pass a proper driver key to it:

import { getRequestInstance } from 'redux-saga-requests';

function* fetchBookSaga() {
  const requestInstance = yield getRequestInstance('fetch');
}

Examples :arrow_up:

I highly recommend to try examples how this package could be used in real applications. You could play with those demos and see what actions are being sent with redux-devtools.

There are following examples currently:

• basic
• advanced
• operations
• Fetch API
• redux-act integration
• low-level-reducers
• mock-and-multiple-drivers

Credits :arrow_up:

This library was inspired by redux-axios-middleware (I highly recommend this library if someone doesn't use Redux-Saga!) and issue in Redux-Saga, when it was recommended not to combine another async middleware with sagas.

Licence :arrow_up:

MIT