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Cannot render and map POST request array promise

I have an API called getQuote and a component called QuoteCard. Inside QuoteCard I'm trying to render an array of users that liked a quote. The API works fine, I have tested it, and the code below for getting the users works fine too.
const Post = async (url, body) => {
let res = await fetch(url, {
method: "POST",
headers: {
"Content-Type": "application/json",
"accept": "*/*"
},
body: JSON.stringify(body)
}).then(r => r.json());
return res;
}
const getAllLikes = async () => {
let users = await Post('api/getQuote', {
id: "639e3aff914d4c4f65418a1b"
})
return users
}
console.log(getAllLikes())
The result is working as expected :
However, when trying to map this promise result array to render it onto the page is where I have problems. I try to render like this:
<div>
{getAllLikes().map((user) => (
<p>{user}</p>
))}
</div>
However, I get an error that states:
getAllLikes(...).map is not a function
I don't understand why this is happening. Why can't I map the array? Is it because it's a promise or something?
And if anyone needs to see the getQuote API, here it is:
//Look ma I wrote an API by myself! :D
import clientPromise from "../../lib/mongodb";
const ObjectId = require('mongodb').ObjectId;
import nc from "next-connect";
const app = nc()
app.post(async function getQuote(req, res) {
const client = await clientPromise;
const db = client.db("the-quotes-place");
try {
let quote = await db.collection('quotes').findOne({
_id: new ObjectId(req.body.id)
})
res.status(200).json(JSON.parse(JSON.stringify(quote.likes.by)));
} catch (e) {
res.status(500).json({
message: "Error getting quote",
success: false
})
console.error(e);
}
})
export default app
Thanks for any help!

It is due to the fact that getAllLikes is an async function and thus it returns promise which does not have a map function.
You can either save it in a state variable before using await Or chain it with .then.
Minimal reproducible example which works
const getAllLikes = async () => {
return ['a', 'b']
}
getAllLikes().then((r) => r.map((g) => { console.log(g) }))
Edit: The above code won't work if directly used with jsx since the return of getAllLikes will still be a promise. Solution would be to save it in a state variable and then using it.

I am from Angular and I believe we call pipe on Observables (or Promises). Map can then be called inside the pipe function
observable$ = getAllLikes().pipe(map( user => <p>{user}</p>))
If there is no pipe, I can only think of manually subscribing (which is not a good practice)
sub$ = getAllLikes().subscribe( user => <p>{user}</p>)
// unsub from sub$ appropriately
// We do this from ngOnDestroy in angular
ngOnDestroy() {
this.sub$?.unsubscribe()
}

Avoid multiple time api calls when user clicks on button accidently multiple times in javascript/React.js [duplicate]

I use axios for ajax requests and reactJS + flux for render UI. In my app there is third side timeline (reactJS component). Timeline can be managed by mouse's scroll. App sends ajax request for the actual data after any scroll event. Problem that processing of request at server can be more slow than next scroll event. In this case app can have several (2-3 usually) requests that already is deprecated because user scrolls further. it is a problem because every time at receiving of new data timeline begins redraw. (Because it's reactJS + flux) Because of this, the user sees the movement of the timeline back and forth several times. The easiest way to solve this problem, it just abort previous ajax request as in jQuery. For example:
$(document).ready(
var xhr;
var fn = function(){
if(xhr && xhr.readyState != 4){
xhr.abort();
}
xhr = $.ajax({
url: 'ajax/progress.ftl',
success: function(data) {
//do something
}
});
};
var interval = setInterval(fn, 500);
);
How to cancel/abort requests in axios?

Axios does not support canceling requests at the moment. Please see this issue for details.
UPDATE: Cancellation support was added in axios v0.15.
EDIT: The axios cancel token API is based on the withdrawn cancelable promises proposal.
UPDATE 2022: Starting from v0.22.0 Axios supports AbortController to cancel requests in fetch API way:
Example:
const controller = new AbortController();
axios.get('/foo/bar', {
signal: controller.signal
}).then(function(response) {
//...
});
// cancel the request
controller.abort()

Using useEffect hook:
useEffect(() => {
const ourRequest = Axios.CancelToken.source() // <-- 1st step
const fetchPost = async () => {
try {
const response = await Axios.get(`endpointURL`, {
cancelToken: ourRequest.token, // <-- 2nd step
})
console.log(response.data)
setPost(response.data)
setIsLoading(false)
} catch (err) {
console.log('There was a problem or request was cancelled.')
}
}
fetchPost()
return () => {
ourRequest.cancel() // <-- 3rd step
}
}, [])
Note: For POST request, pass cancelToken as 3rd argument
Axios.post(`endpointURL`, {data}, {
cancelToken: ourRequest.token, // 2nd step
})

Typically you want to cancel the previous ajax request and ignore it's coming response, only when a new ajax request of that instance is started, for this purpose, do the following:
Example: getting some comments from API:
// declare an ajax request's cancelToken (globally)
let ajaxRequest = null;
function getComments() {
// cancel previous ajax if exists
if (ajaxRequest ) {
ajaxRequest.cancel();
}
// creates a new token for upcomming ajax (overwrite the previous one)
ajaxRequest = axios.CancelToken.source();
return axios.get('/api/get-comments', { cancelToken: ajaxRequest.token }).then((response) => {
console.log(response.data)
}).catch(function(err) {
if (axios.isCancel(err)) {
console.log('Previous request canceled, new request is send', err.message);
} else {
// handle error
}
});
}

import React, { Component } from "react";
import axios from "axios";
const CancelToken = axios.CancelToken;
let cancel;
class Abc extends Component {
componentDidMount() {
this.Api();
}
Api() {
// Cancel previous request
if (cancel !== undefined) {
cancel();
}
axios.post(URL, reqBody, {
cancelToken: new CancelToken(function executor(c) {
cancel = c;
}),
})
.then((response) => {
//responce Body
})
.catch((error) => {
if (axios.isCancel(error)) {
console.log("post Request canceled");
}
});
}
render() {
return <h2>cancel Axios Request</h2>;
}
}
export default Abc;

There is really nice package with few examples of usage called axios-cancel.
I've found it very helpful.
Here is the link: https://www.npmjs.com/package/axios-cancel

https://github.com/axios/axios#cancellation
const CancelToken = axios.CancelToken;
const source = CancelToken.source();
let url = 'www.url.com'
axios.get(url, {
progress: false,
cancelToken: source.token
})
.then(resp => {
alert('done')
})
setTimeout(() => {
source.cancel('Operation canceled by the user.');
},'1000')

This is how I did it using promises in node. Pollings stop after making the first request.
var axios = require('axios');
var CancelToken = axios.CancelToken;
var cancel;
axios.get('www.url.com',
{
cancelToken: new CancelToken(
function executor(c) {
cancel = c;
})
}
).then((response) =>{
cancel();
})

Using cp-axios wrapper you able to abort your requests with three diffent types of the cancellation API:
1. Promise cancallation API (CPromise):
Live browser example
const cpAxios= require('cp-axios');
const url= 'https://run.mocky.io/v3/753aa609-65ae-4109-8f83-9cfe365290f0?mocky-delay=5s';
const chain = cpAxios(url)
.timeout(5000)
.then(response=> {
console.log(`Done: ${JSON.stringify(response.data)}`)
}, err => {
console.warn(`Request failed: ${err}`)
});
setTimeout(() => {
chain.cancel();
}, 500);
2. Using AbortController signal API:
const cpAxios= require('cp-axios');
const CPromise= require('c-promise2');
const url= 'https://run.mocky.io/v3/753aa609-65ae-4109-8f83-9cfe365290f0?mocky-delay=5s';
const abortController = new CPromise.AbortController();
const {signal} = abortController;
const chain = cpAxios(url, {signal})
.timeout(5000)
.then(response=> {
console.log(`Done: ${JSON.stringify(response.data)}`)
}, err => {
console.warn(`Request failed: ${err}`)
});
setTimeout(() => {
abortController.abort();
}, 500);
3. Using a plain axios cancelToken:
const cpAxios= require('cp-axios');
const url= 'https://run.mocky.io/v3/753aa609-65ae-4109-8f83-9cfe365290f0?mocky-delay=5s';
const source = cpAxios.CancelToken.source();
cpAxios(url, {cancelToken: source.token})
.timeout(5000)
.then(response=> {
console.log(`Done: ${JSON.stringify(response.data)}`)
}, err => {
console.warn(`Request failed: ${err}`)
});
setTimeout(() => {
source.cancel();
}, 500);
4. Usage in a custom React hook (Live Demo):
import React from "react";
import { useAsyncEffect } from "use-async-effect2";
import cpAxios from "cp-axios";
/*
Note: the related network request will be aborted as well
Check out your network console
*/
function TestComponent({ url, timeout }) {
const [cancel, done, result, err] = useAsyncEffect(
function* () {
return (yield cpAxios(url).timeout(timeout)).data;
},
{ states: true, deps: [url] }
);
return (
<div>
{done ? (err ? err.toString() : JSON.stringify(result)) : "loading..."}
<button onClick={cancel} disabled={done}>
Cancel async effect (abort request)
</button>
</div>
);
}
Update
Axios v0.22.0+ supports AbortController natively:
const controller = new AbortController();
axios.get('/foo/bar', {
signal: controller.signal
}).then(function(response) {
//...
});
// cancel the request
controller.abort()

Starting from v0.22.0 Axios supports AbortController to cancel requests in fetch API way:
const controller = new AbortController();
axios.get('/foo/bar', {
signal: controller.signal
}).then(function(response) {
//...
});
// cancel the request
controller.abort()
CancelToken deprecated
You can also cancel a request using a CancelToken.
The axios cancel token API is based on the withdrawn cancelable promises proposal.
This API is deprecated since v0.22.0 and shouldn't be used in new projects
You can create a cancel token using the CancelToken.source factory as shown below:

import {useState, useEffect} from 'react'
export function useProfileInformation({accessToken}) {
const [profileInfo, setProfileInfo] = useState(null)
useEffect(() => {
const abortController = new AbortController()
window
.fetch('https://api.example.com/v1/me', {
headers: {Authorization: `Bearer ${accessToken}`},
method: 'GET',
mode: 'cors',
signal: abortController.signal,
})
.then(res => res.json())
.then(res => setProfileInfo(res.profileInfo))
return function cancel() {
abortController.abort()
}
}, [accessToken])
return profileInfo
}
// src/app.jsx
import React from 'react'
import {useProfileInformation} from './hooks/useProfileInformation'
export function App({accessToken}) {
try {
const profileInfo = useProfileInformation({accessToken})
if (profileInfo) {
return <h1>Hey, ${profileInfo.name}!</h1>
} else {
return <h1>Loading Profile Information</h1>
}
} catch (err) {
return <h1>Failed to load profile. Error: {err.message}</h1>
}
}

How to Redirect if API call fails in React Js?

I'm trying to implement Redirect in my react js App so if API call returns status other that 200, I can redirect users to according pages. The problem is that Redirect doesn't work. My code so far:
function catchErr(res) {
try {
if (res.status === 200) {
return res.json();
} else if (res.status === 404) {
<Redirect to="/404" // doesn't redirect to this route
console.log("404") // prints 404
throw Error(res.status);
}
else {
if (res.ok) {
return res.data;
}
}
} catch (err) {
console.log(err);
}
}
export async function getData() {
let getParams = {
method: "GET",
headers: {
Accept: "application/json",
"Content-Type": "application/json",
},
};
const data = await fetch(url, obj)
.then((res) => catchErr(res))
.then((res) => {
return res.data;
});
return data;
}
My api call is a function in separate file, it's not react functional component so I can't use useState hook to store state or use useHistory(history.push) inside getData() function. At the moment api call works great, catchErr() console.loges 404 if res.status === 404 but doesn't redirect to "/404" as I need to. I can't figure out why Redirect wouldn't work in this case, please help.

You can't call JSX like that in the middle of a function. You'll need to refactor your code to handle the failures in a React component and either set some state to conditionally render a Redirect component into the DOM or access the history object to do an imperative redirect, i.e. history.replace.
Here's an example component using history.replace.
import { useHistory } from 'react-router-dom';
const MyComponent = () => {
const history = useHistory();
...
useEffect(() => {
const fetchData = async () => {
// set any loading state
try {
const response = await fetch(url, options);
// process response, throw error if STATUS 404
} catch(error) {
// handle any error responses and redirect
history.replace("/404");
} finally {
// clear any loading state
}
}
fetchData();
}, []);
...
return (
<div>My JSX</div>
)
};

Use function as react hook?

I wanted to use a function as a react hook to wrap fetch requests to an API.
My current hook:
export function useAPI(url, options={}) {
const [auth, setAuth] = useGlobal('auth');
const [call, setCall] = useState(undefined);
const apiFetch = async () => {
const res = await fetch(url, {
...options,
});
if (!res.ok)
throw await res.json();
return await res.json();
};
function fetchFunction() {
fetch(url, {
...options,
});
}
useEffect(() => {
// Only set function if undefined, to prevent setting unnecessarily
if (call === undefined) {
setCall(fetchFunction);
//setCall(apiFetch);
}
}, [auth]);
return call
}
That way, in a react function, I could do the following...
export default function LayoutDash(props) {
const fetchData = useAPI('/api/groups/mine/'); // should return a function
useEffect(() => {
fetchData(); // call API on mount
}, []);
render(...stuff);
}
But it seems react isn't able to use functions in hooks like that. If I set call to fetchFunction, it returns undefined. If I set it to apiFetch, it executes and returns a promise instead of a function that I can call when I want to in the other component.
I initially went for react hooks because I can't use useGlobal outside react components/hooks. And I would need to have access to the reactn global variable auth to check if the access token is expired.
So what would be the best way to go about this? The end goal is being able to pass (url, options) to a function that will be a wrapper to a fetch request. (It checks if auth.access is expired, and if so, obtains a new access token first, then does the api call, otherwise it just does the API call). If there's another way I should go about this other than react hooks, I'd like to know.

Instead of putting your function into useState, consider using useCallback. Your code would look something like this:
export function useAPI(url, options={}) {
const [auth, setAuth] = useGlobal('auth');
function fetchFunction() {
fetch(url, {
...options,
});
}
const call = useCallback(fetchFunction, [auth]);
const apiFetch = async () => {
const res = await fetch(url, {
...options,
});
if (!res.ok)
throw await res.json();
return await res.json();
};
return call
}
The returned function is recreated whenever auth changes, therefore somewhat mimicking what you tried to do with useEffect

Refactoring breaks initial state

React (from create-react-app) with MobX. Using axios for async backend API calls.
This code works. The initial state (array of issues) is populated, and the webpage presenting this component renders with initial content from state.
import { observable, computed, autorun, reaction } from 'mobx'
import axios from 'axios'
class IssuesStore {
#observable issues = []
constructor() {
autorun(() => console.log("Autorun:" + this.buildIssues))
reaction(
() => this.issues,
issues => console.log("Reaction: " + issues.join(", "))
)
}
getIssues(data) {
return data.map((issue) => ({title: issue.name, url: issue.url, labels: issue.labels}))
}
#computed get buildIssues() {
const authToken = 'token ' + process.env.REACT_APP_GH_OAUTH_TOKEN
axios.get(`https://api.github.com/repos/${process.env.REACT_APP_GH_USER}/gh-issues-app/issues`,
{ 'headers': {'Authorization': authToken} })
.then(response => {
console.log(response)
this.issues = this.getIssues(response.data)
return this.issues
})
.catch(function(response) {
console.log(response)
})
}
}
export default IssuesStore
In an attempt to separate API invocation promises from individual components and stores, I pulled out the axios call into a separate js file, as a collection of functions:
import axios from 'axios'
const authToken = 'token ' + process.env.REACT_APP_GH_OAUTH_TOKEN
export function loadIssues() {
return this.apiPromise(
`https://api.github.com/repos/${process.env.REACT_APP_GH_USER}/gh-issues-app/issues`,
{ 'headers': {'Authorization': authToken} }
)
}
export function apiPromise(endpoint, options) {
return axios.get(endpoint, options)
.then((response) => {
// console.log("response: " + JSON.stringify(response, null, 2))
return response.data.map((issue) => ({title: issue.name, url: issue.url, labels: issue.labels}))
})
.catch(function(response) {
console.log(response)
})
}
Now, my store looks like this:
import { observable, computed, autorun, reaction } from 'mobx'
import * as github from '../api/github'
class IssuesStore {
#observable issues = []
constructor() {
autorun(() => console.log("Autorun:" + this.buildIssues))
reaction(
() => this.issues,
issues => console.log("Reaction: " + issues.join(", "))
)
}
#computed get buildIssues() {
this.issues = github.loadIssues().data
return this.issues
}
}
export default IssuesStore
Much smaller... but the webpage now throws an error because it now sees the initial state of issues as undefined on first render.
Uncaught TypeError: Cannot read property 'map' of undefined
The promise completes successfully later on (as it should), but by then it's too late. Sure, I can set up a few null checks in my rendering components to not run .map or other such functions on empty or as-yet-undefined variables.
But why does the code work with no initial rendering errors before the refactoring, and not after? I thought the refactoring was effectively maintaining the same logic flow, but I must be missing something?

In your refactored version
github.loadIssues().data
Is always going to be undefined because the data property on that Promise will always be undefined.
In the original version, this.issues was only ever set once data returned from the api, so the only values that it was ever set to were the initial value [] and the filled array from the api response.
In yours, the three states are [] -> undefined -> and the filled array.
buildIssues should look something like this:
#computed get buildIssues() {
github.loadIssues().then((data) => {
this.issues = data
}).catch((err) => {
// handle err.
})
}