Develop Reference

React Prop returning Null as it relies on state

Hopefully a simply one.
I make an API call in my component which brings down some account information such as AccountUid, Category etc, i use state to set these.
useEffect(() => {
fetch(feed_url, {
headers: {
//Headers for avoiding CORS Error and Auth Token in a secure payload
"Access-Control-Allow-Origin": "*",
Authorization: process.env.REACT_APP_AUTH_TOKEN,
},
})
//Return JSON if the Response is recieved
.then((response) => {
if (response.ok) {
return response.json();
}
throw response;
})
//Set the Account Name state to the JSON data recieved
.then((accountDetails) => {
setAccountDetails(accountDetails);
console.log(accountDetails.accounts[0].accountUid);
console.log(accountDetails.accounts[0].defaultCategory);
})
//Log and Error Message if there is an issue in the Request
.catch((error) => {
console.error("Error fetching Transaction data: ", error);
});
}, [feed_url]);
This Works perfectly well and it Logs the correct values in my .then when testing it.
The issue however is that i want to pass these down as props. But i get an error that they are being returned as null (My default state).. i presume as they're jumping ahead.
<div className="App">
<GetAccountName
accountUID={accountDetails.accounts[0].accountUID}
defCategory={accountDetails.accounts[0].defaultCategory}
/>
</div>
How do i pass the the 2 details im logging as props?? I've tried setting default state to "" instead of null and just get that it is undefined.

If you dont want to use conditional render in your child component, so you should try optional chaining
<GetAccountName
accountUID={accountDetails?.accounts?.[0]?.accountUID}
defCategory={accountDetails?.accounts?.[0]?.defaultCategory}
/>

Since fetching is asyncronous, the most common way is to show some loading indicator (like a spinner) & once the data come in, show the component instead.
If you don't need an indicator, you might just return null.
The general idea is to manipulate some intermediary states (e.g. data, isError) based on the promise state.
Check out react-query library example or a lighter abstraction like useFetch hook to see how they manage it.
Here's a sample implementation of useFetch taken from this article:
const useFetch = (url, options) => {
const [response, setResponse] = React.useState(null);
const [error, setError] = React.useState(null);
const [abort, setAbort] = React.useState(() => {});
React.useEffect(() => {
const fetchData = async () => {
try {
const abortController = new AbortController();
const signal = abortController.signal;
setAbort(abortController.abort);
const res = await fetch(url, {...options, signal});
const json = await res.json();
setResponse(json);
} catch (error) {
setError(error);
}
};
fetchData();
return () => {
abort();
}
}, []);
return { response, error, abort };
};

Canceling request of nuxt fetch hook

Since Nuxt's fetch hooks cannot run in parallel, I needed a way to cancel requests done in fetch hook when navigating to some other route so users don't have to wait for the first fetch to complete when landed on the homepage navigated to some other. So I found this approach: How to cancel all Axios requests on route change
So I've created these plugin files for Next:
router.js
export default ({ app, store }) => {
// Every time the route changes (fired on initialization too)
app.router.beforeEach((to, from, next) => {
store.dispatch('cancel/cancel_pending_requests')
next()
})
}
axios.js
export default function ({ $axios, redirect, store }) {
$axios.onRequest((config) => {
const source = $axios.CancelToken.source()
config.cancelToken = source.token
store.commit('cancel/ADD_CANCEL_TOKEN', source)
return config
}, function (error) {
return Promise.reject(error)
})
}
and a small vuex store for the cancel tokens:
export const state = () => ({
cancelTokens: []
})
export const mutations = {
ADD_CANCEL_TOKEN (state, token) {
state.cancelTokens.push(token)
},
CLEAR_CANCEL_TOKENS (state) {
state.cancelTokens = []
}
}
export const actions = {
cancel_pending_requests ({ state, commit }) {
state.cancelTokens.forEach((request, i) => {
if (request.cancel) {
request.cancel('Request canceled')
}
})
commit('CLEAR_CANCEL_TOKENS')
}
}
Now this approach works fine and I can see requests get canceled with 499 on route change, however, it is flooding my devtools console with "Error in fetch()" error. Is there some preferred/better way to do this?
Example of fetch hook here:
async fetch () {
await this.$store.dispatch('runs/getRunsOverview')
}
Example of dispatched action:
export const actions = {
async getRunsOverview ({ commit }) {
const data = await this.$axios.$get('api/frontend/runs')
commit('SET_RUNS', data)
}
}
Edit: I forgot to mention that I'm using fetch here with fetchOnServer set to False to display some loading placeholder to users.
The main problem is the flooded console with error, but I can also see that it also enters the $fetchState.error branch in my template, which displays div with "Something went wrong" text before route switches.
Edit 2:
Looked closer where this error comes from and it's mixin file fetch.client.js in .nuxt/mixins directory. Pasting the fetch function code below:
async function $_fetch() {
this.$nuxt.nbFetching++
this.$fetchState.pending = true
this.$fetchState.error = null
this._hydrated = false
let error = null
const startTime = Date.now()
try {
await this.$options.fetch.call(this)
} catch (err) {
if (process.dev) {
console.error('Error in fetch():', err)
}
error = normalizeError(err)
}
const delayLeft = this._fetchDelay - (Date.now() - startTime)
if (delayLeft > 0) {
await new Promise(resolve => setTimeout(resolve, delayLeft))
}
this.$fetchState.error = error
this.$fetchState.pending = false
this.$fetchState.timestamp = Date.now()
this.$nextTick(() => this.$nuxt.nbFetching--)
}
Have also tried to have everything using async/await as #kissu suggested in comments but with no luck :/

How to dispatch an action from within another action in another Vuex store module?

CONTEXT
I have two store modules : "Meetings" and "Demands".
Within store "Demands" I have "getDemands" action, and within store "Meetings" I have "getMeetings" action. Prior to access meetings's data in Firestore, I need to know demands's Id (ex.: demands[i].id), so "getDemands" action must run and complete before "getMeetings" is dispatched.
Vuex documentation dispatching-action is very complete, but still, I don't see how to fit it in my code. There are also somme other good answered questions on the topic here :
Vue - call async action only after first one has finished
Call an action from within another action
I would like to know the best way to implement what I'm trying to accomplish. From my perspective this could be done by triggering one action from another, or using async / await, but I'm having trouble implementing it.
dashboard.vue
computed: {
demands() {
return this.$store.state.demands.demands;
},
meetings() {
return this.$store.state.meetings.meetings;
}
},
created() {
this.$store.dispatch("demands/getDemands");
//this.$store.dispatch("meetings/getMeetings"); Try A : Didn't work, seems like "getMeetings" must be called once "getDemands" is completed
},
VUEX store
Module A – demands.js
export default {
namespaced: true,
state: {
demands:[], //demands is an array of objects
},
actions: {
// Get demands from firestore UPDATED
async getDemands({ rootState, commit, dispatch }) {
const { uid } = rootState.auth.user
if (!uid) return Promise.reject('User is not logged in!')
const userRef = db.collection('profiles').doc(uid)
db.collection('demands')
.where('toUser', "==", userRef)
.get()
.then(async snapshot => {
const demands = await Promise.all(
snapshot.docs.map(doc =>
extractDataFromDemand({ id: doc.id, demand: doc.data() })
)
)
commit('setDemands', { resource: 'demands', demands })
console.log(demands) //SECOND LOG
})
await dispatch("meetings/getMeetings", null, { root: true }) //UPDATE
},
...
mutations: {
setDemands(state, { resource, demands }) {
state[resource] = demands
},
...
Module B – meetings.js
export default {
namespaced: true,
state: {
meetings:[],
},
actions: {
// Get meeting from firestore UPDATED
getMeetings({ rootState, commit }) {
const { uid } = rootState.auth.user
if (!uid) return Promise.reject('User is not logged in!')
const userRef = db.collection('profiles').doc(uid)
const meetings = []
db.collection('demands')
.where('toUser', "==", userRef)
.get()
.then(async snapshot => {
await snapshot.forEach((document) => {
document.ref.collection("meetings").get()
.then(async snapshot => {
await snapshot.forEach((document) => {
console.log(document.id, " => ", document.data()) //LOG 3, 4
meetings.push(document.data())
})
})
})
})
console.log(meetings) // FIRST LOG
commit('setMeetings', { resource: 'meetings', meetings })
},
...
mutations: {
setMeetings(state, { resource, meetings }) {
state[resource] = meetings
},
...

Syntax:
dispatch(type: string, payload?: any, options?: Object): Promise<any
Make the call right
dispatch("meetings/getMeetings", null, {root:true})

How do I test axios in Jest?

I have this action in React:
export function fetchPosts() {
const request = axios.get(`${WORDPRESS_URL}`);
return {
type: FETCH_POSTS,
payload: request
}
}
How do I test Axios in this case?
Jest has this use case on their site for asynchronous code where they use a mock function, but can I do this with Axios?
Reference: An Async Example
I have done this so far to test that it is returning the correct type:
it('should dispatch actions with the correct type', () => {
store.dispatch(fetchPosts());
let action = store.getActions();
expect(action[0].type).toBe(FETCH_POSTS);
});
How can I pass in mock data and test that it returns?

Without using any other libraries:
import * as axios from "axios";
// Mock out all top level functions, such as get, put, delete and post:
jest.mock("axios");
// ...
test("good response", () => {
axios.get.mockImplementation(() => Promise.resolve({ data: {...} }));
// ...
});
test("bad response", () => {
axios.get.mockImplementation(() => Promise.reject({ ... }));
// ...
});
It is possible to specify the response code:
axios.get.mockImplementation(() => Promise.resolve({ status: 200, data: {...} }));
It is possible to change the mock based on the parameters:
axios.get.mockImplementation((url) => {
if (url === 'www.example.com') {
return Promise.resolve({ data: {...} });
} else {
//...
}
});
Jest v23 introduced some syntactic sugar for mocking Promises:
axios.get.mockImplementation(() => Promise.resolve({ data: {...} }));
It can be simplified to
axios.get.mockResolvedValue({ data: {...} });
There is also an equivalent for rejected promises: mockRejectedValue.
Further Reading:
Jest mocking documentation
A GitHub discussion that explains about the scope of the jest.mock("axios") line.
A related question which addresses applying the techniques above to Axios request interceptors.
Using jest functions like mockImplementation in TypeScript: Typescript and Jest: Avoiding type errors on mocked functions

I used axios-mock-adapter.
In this case the service is described in ./chatbot.
In the mock adapter you specify what to return when the API endpoint is consumed.
import axios from 'axios';
import MockAdapter from 'axios-mock-adapter';
import chatbot from './chatbot';
describe('Chatbot', () => {
it('returns data when sendMessage is called', done => {
var mock = new MockAdapter(axios);
const data = { response: true };
mock.onGet('https://us-central1-hutoma-backend.cloudfunctions.net/chat').reply(200, data);
chatbot.sendMessage(0, 'any').then(response => {
expect(response).toEqual(data);
done();
});
});
});
You can see it the whole example here:
Service:
https://github.com/lnolazco/hutoma-test/blob/master/src/services/chatbot.js
Test:
https://github.com/lnolazco/hutoma-test/blob/master/src/services/chatbot.test.js

I could do that following the steps:
Create a folder __mocks__/ (as pointed by #Januartha comment)
Implement an axios.js mock file
Use my implemented module on test
The mock will happen automatically
Example of the mock module:
module.exports = {
get: jest.fn((url) => {
if (url === '/something') {
return Promise.resolve({
data: 'data'
});
}
}),
post: jest.fn((url) => {
if (url === '/something') {
return Promise.resolve({
data: 'data'
});
}
if (url === '/something2') {
return Promise.resolve({
data: 'data2'
});
}
}),
create: jest.fn(function () {
return this;
})
};

Look at this
The function to test album.js
const fetchAlbum = function () {
return axios
.get("https://jsonplaceholder.typicode.com/albums/2")
.then((response) => {
return response.data;
});
};
The test album.test.js
const axios = require("axios");
const { fetchAlbum } = require("../utils.js");
jest.mock("axios");
test("mock axios get function", async () => {
expect.assertions(1);
const album = {
userId: 1,
id: 2,
title: "sunt qui excepturi placeat culpa",
};
const payload = { data: album };
// Now mock axios get method
axios.get = jest.fn().mockResolvedValue(payload);
await expect(fetchAlbum()).resolves.toEqual(album);
});

I've done this with nock, like so:
import nock from 'nock'
import axios from 'axios'
import httpAdapter from 'axios/lib/adapters/http'
axios.defaults.adapter = httpAdapter
describe('foo', () => {
it('bar', () => {
nock('https://example.com:443')
.get('/example')
.reply(200, 'some payload')
// test...
})
})

For those looking to use axios-mock-adapter in place of the mockfetch example in the Redux documentation for async testing, I successfully used the following:
File actions.test.js:
describe('SignInUser', () => {
var history = {
push: function(str) {
expect(str).toEqual('/feed');
}
}
it('Dispatches authorization', () => {
let mock = new MockAdapter(axios);
mock.onPost(`${ROOT_URL}/auth/signin`, {
email: 'test#test.com',
password: 'test'
}).reply(200, {token: 'testToken' });
const expectedActions = [ { type: types.AUTH_USER } ];
const store = mockStore({ auth: [] });
return store.dispatch(actions.signInUser({
email: 'test#test.com',
password: 'test',
}, history)).then(() => {
expect(store.getActions()).toEqual(expectedActions);
});
});
In order to test a successful case for signInUser in file actions/index.js:
export const signInUser = ({ email, password }, history) => async dispatch => {
const res = await axios.post(`${ROOT_URL}/auth/signin`, { email, password })
.catch(({ response: { data } }) => {
...
});
if (res) {
dispatch({ type: AUTH_USER }); // Test verified this
localStorage.setItem('token', res.data.token); // Test mocked this
history.push('/feed'); // Test mocked this
}
}
Given that this is being done with jest, the localstorage call had to be mocked. This was in file src/setupTests.js:
const localStorageMock = {
removeItem: jest.fn(),
getItem: jest.fn(),
setItem: jest.fn(),
clear: jest.fn()
};
global.localStorage = localStorageMock;

New tools for testing have been introduced since the question was initially answered.
The problem with mocking is that you often test the mock and not the real context of your code, leaving some areas of this context untested.
An improvement over telling axios what promise to return is intercepting http requests via Service Workers.
Service worker is a client-side programmable proxy between your web app and the outside world. So instead of mocking promise resolution it is a more broader solution to mock the proxy server itself, intercepting requests to be tested. Since the interception happens on the network level, your application knows nothing about the mocking.
You can use msw (Mock Service Worker) library to do just that. Here is a short video explaining how it works.
The most basic setup I can think of is this:
1️⃣ set up handlers, which are similar to express.js routing methods;
2️⃣ set up mock server and pass handlers as it’s arguments;
3️⃣ configure tests to so that mock server will intercept our requests;
4️⃣ perform tests;
5️⃣ close mock server.
Say you want to test the following feature:
import axios from "axios";
export const fetchPosts = async () => {
const request = await axios.get("/some/endpoint/");
return {
payload: request,
};
};
Then test could look like this:
import { rest } from "msw";
import { setupServer } from "msw/node";
import fetchPosts from "./somewhere";
// handlers are usually saved in separate file(s) in one destined place of the app,
// so that you don't have to search for them when the endpoints have changed
const handlers = [ 1️⃣
rest.get("/some/endpoint/", (req, res, ctx) =>
res(ctx.json({ message: "success" }))
),
];
const server = setupServer(...handlers); 2️⃣
beforeAll(() => {
server.listen(); 3️⃣
});
describe("fetchPosts", () => {
it("should return 'success' message", async () => {
const resp = await fetchPosts();
expect(resp.payload?.data?.message).toEqual("success"); 4️⃣
});
});
afterAll(() => {
server.close(); 5️⃣
});
The configuration may be different depending on framework you are using. Some general examples for, among others, React (both REST and GraphQL) and Angular can be found on MSW’ repo. A Vue example is provided by VueMastery.
You can also find examples on MSW' recipes page.

How to use Redux to refresh JWT token?

Our React Native Redux app uses JWT tokens for authentication. There are many actions that require such tokens and a lot of them are dispatched simultaneously e.g. when app loads.
E.g.
componentDidMount() {
dispath(loadProfile());
dispatch(loadAssets());
...
}
Both loadProfile and loadAssets require JWT. We save the token in the state and AsyncStorage. My question is how to handle token expiration.
Originally I was going to use middleware for handling token expiration
// jwt-middleware.js
export function refreshJWTToken({ dispatch, getState }) {
return (next) => (action) => {
if (isExpired(getState().auth.token)) {
return dispatch(refreshToken())
.then(() => next(action))
.catch(e => console.log('error refreshing token', e));
}
return next(action);
};
}
The problem that I ran into was that refreshing of the token will happen for both loadProfile and loadAssets actions because at the time when they are dispatch the token will be expired. Ideally I would like to "pause" actions that require authentication until the token is refreshed. Is there a way to do that with middleware?

I found a way to solve this. I am not sure if this is best practice approach and there are probably some improvements that could be made to it.
My original idea stays: JWT refresh is in the middleware. That middleware has to come before thunk if thunk is used.
...
const createStoreWithMiddleware = applyMiddleware(jwt, thunk)(createStore);
Then in the middleware code we check to see if token is expired before any async action. If it is expired we also check if we are already are refreshing the token -- to be able to have such check we add promise for fresh token to the state.
import { refreshToken } from '../actions/auth';
export function jwt({ dispatch, getState }) {
return (next) => (action) => {
// only worry about expiring token for async actions
if (typeof action === 'function') {
if (getState().auth && getState().auth.token) {
// decode jwt so that we know if and when it expires
var tokenExpiration = jwtDecode(getState().auth.token).<your field for expiration>;
if (tokenExpiration && (moment(tokenExpiration) - moment(Date.now()) < 5000)) {
// make sure we are not already refreshing the token
if (!getState().auth.freshTokenPromise) {
return refreshToken(dispatch).then(() => next(action));
} else {
return getState().auth.freshTokenPromise.then(() => next(action));
}
}
}
}
return next(action);
};
}
The most important part is refreshToken function. That function needs to dispatch action when token is being refreshed so that the state will contain the promise for the fresh token. That way if we dispatch multiple async actions that use token auth simultaneously the token gets refreshed only once.
export function refreshToken(dispatch) {
var freshTokenPromise = fetchJWTToken()
.then(t => {
dispatch({
type: DONE_REFRESHING_TOKEN
});
dispatch(saveAppToken(t.token));
return t.token ? Promise.resolve(t.token) : Promise.reject({
message: 'could not refresh token'
});
})
.catch(e => {
console.log('error refreshing token', e);
dispatch({
type: DONE_REFRESHING_TOKEN
});
return Promise.reject(e);
});
dispatch({
type: REFRESHING_TOKEN,
// we want to keep track of token promise in the state so that we don't try to refresh
// the token again while refreshing is in process
freshTokenPromise
});
return freshTokenPromise;
}
I realize that this is pretty complicated. I am also a bit worried about dispatching actions in refreshToken which is not an action itself. Please let me know of any other approach you know that handles expiring JWT token with redux.

Instead of "waiting" for an action to finish, you could instead keep a store variable to know if you're still fetching tokens:
Sample reducer
const initialState = {
fetching: false,
};
export function reducer(state = initialState, action) {
switch(action.type) {
case 'LOAD_FETCHING':
return {
...state,
fetching: action.fetching,
}
}
}
Now the action creator:
export function loadThings() {
return (dispatch, getState) => {
const { auth, isLoading } = getState();
if (!isExpired(auth.token)) {
dispatch({ type: 'LOAD_FETCHING', fetching: false })
dispatch(loadProfile());
dispatch(loadAssets());
} else {
dispatch({ type: 'LOAD_FETCHING', fetching: true })
dispatch(refreshToken());
}
};
}
This gets called when the component mounted. If the auth key is stale, it will dispatch an action to set fetching to true and also refresh the token. Notice that we aren't going to load the profile or assets yet.
New component:
componentDidMount() {
dispath(loadThings());
// ...
}
componentWillReceiveProps(newProps) {
const { fetching, token } = newProps; // bound from store
// assuming you have the current token stored somewhere
if (token === storedToken) {
return; // exit early
}
if (!fetching) {
loadThings()
}
}
Notice that now you attempt to load your things on mount but also under certain conditions when receiving props (this will get called when the store changes so we can keep fetching there) When the initial fetch fails, it will trigger the refreshToken. When that is done, it'll set the new token in the store, updating the component and hence calling componentWillReceiveProps. If it's not still fetching (not sure this check is necessary), it will load things.

I made a simple wrapper around redux-api-middleware to postpone actions and refresh access token.
middleware.js
import { isRSAA, apiMiddleware } from 'redux-api-middleware';
import { TOKEN_RECEIVED, refreshAccessToken } from './actions/auth'
import { refreshToken, isAccessTokenExpired } from './reducers'
export function createApiMiddleware() {
const postponedRSAAs = []
return ({ dispatch, getState }) => {
const rsaaMiddleware = apiMiddleware({dispatch, getState})
return (next) => (action) => {
const nextCheckPostponed = (nextAction) => {
// Run postponed actions after token refresh
if (nextAction.type === TOKEN_RECEIVED) {
next(nextAction);
postponedRSAAs.forEach((postponed) => {
rsaaMiddleware(next)(postponed)
})
} else {
next(nextAction)
}
}
if(isRSAA(action)) {
const state = getState(),
token = refreshToken(state)
if(token && isAccessTokenExpired(state)) {
postponedRSAAs.push(action)
if(postponedRSAAs.length === 1) {
return rsaaMiddleware(nextCheckPostponed)(refreshAccessToken(token))
} else {
return
}
}
return rsaaMiddleware(next)(action);
}
return next(action);
}
}
}
export default createApiMiddleware();
I keep tokens in the state, and use a simple helper to inject Acess token into a request headers
export function withAuth(headers={}) {
return (state) => ({
...headers,
'Authorization': `Bearer ${accessToken(state)}`
})
}
So redux-api-middleware actions stays almost unchanged
export const echo = (message) => ({
[RSAA]: {
endpoint: '/api/echo/',
method: 'POST',
body: JSON.stringify({message: message}),
headers: withAuth({ 'Content-Type': 'application/json' }),
types: [
ECHO_REQUEST, ECHO_SUCCESS, ECHO_FAILURE
]
}
})
I wrote the article and shared the project example, that shows JWT refresh token workflow in action

I think that redux is not the right tool for enforcing the atomicity of token refresh.
Instead I can offer you an atomic function that can be called from anywhere and ensures that you will always get a valid token:
/*
The non-atomic refresh function
*/
const refreshToken = async () => {
// Do whatever you need to do here ...
}
/*
Promise locking-queueing structure
*/
var promiesCallbacks = [];
const resolveQueue = value => {
promiesCallbacks.forEach(x => x.resolve(value));
promiesCallbacks = [];
};
const rejectQueue = value => {
promiesCallbacks.forEach(x => x.reject(value));
promiesCallbacks = [];
};
const enqueuePromise = () => {
return new Promise((resolve, reject) => {
promiesCallbacks.push({resolve, reject});
});
};
/*
The atomic function!
*/
var actionInProgress = false;
const refreshTokenAtomically = () => {
if (actionInProgress) {
return enqueuePromise();
}
actionInProgress = true;
return refreshToken()
.then(({ access }) => {
resolveQueue(access);
return access;
})
.catch((error) => {
rejectQueue(error);
throw error;
})
.finally(() => {
actionInProgress = false;
});
};
Posted also here: https://stackoverflow.com/a/68154638/683763