How to avoid sending multiple duplicate AJAX requests in axios - javascript

Is it possible to automatically throttle all requests going to a particular list of endpoints using axios? Perhaps using axios interceptor?
Currently I throttle the user action that sends the axios request, but the problem with that is that I have to write this everywhere I have a user action that results in some AJAX request. Like this
const throttledDismissNotification = throttle(dismissNotification, 1000)
const dismiss = (event: any) => {
throttledDismissNotification();
};
render() {
return (
<Button onClick={dismiss}>Dismiss Notification</Button>
)
}
This results in a lot of clutter and I was wondering if this could be automated.
Something like:
if(request.url in listOfEndpointsToThrottle && request.params in cacheOfPreviousRequestsToThisEndpoint) {
StopRequest();
}
Obviously this is pseudocode but you get the idea.

Perhaps you could try to use the Cancellation feature that axios provides.
With it, you can ensure that you don't have any two (or more, depending on your implementation) similar requests in a pending state.
Below, you will find a small simplified example of how to ensure that only the latest request is processed. You can adjust it a bit to make it function like a pool of requests
import axios, { CancelToken } from 'axios';
const pendingRequests = {};
const makeCancellable = (headers, requestId) => {
if (!requestId) {
return headers;
}
if (pendingRequests[requestId]) {
// cancel an existing request
pendingRequests[requestId].cancel();
}
const source = CancelToken.source();
const newHeaders = {
...headers,
cancelToken: source.token
};
pendingRequests[requestId] = source;
return newHeaders;
};
const request = ({
url,
method = 'GET',
headers,
id
}) => {
const requestConfig = {
url,
method,
headers: makeCancellable(headers || {}, id)
};
return axios.request(requestConfig)
.then((res) => {
delete pendingRequests[id];
return ({ data: res.data });
})
.catch((error) => {
delete pendingRequests[id];
if (axios.isCancel(error)) {
console.log(`A request to url ${url} was cancelled`); // cancelled
} else {
return handleReject(error);
}
});
};
export default request;

It's quite easy to throttle an axios request itself. The real headache is how to handle the promises that are returned from nullified requests. What is considered sane behavior when dealing with promises that are returned from a nullified axios request? Should they stay pending forever?
I don't see any perfect solution to this problem. But then I come to a solution that is kind of cheating:
What if we don't throttle the axios call, instead we throttle the actual XMLHttpRequest?
This makes things way easier, because it avoids the promise problem, and it's easier to implement. The idea is to implement a cache for recent requests, and if a new request matches a recent one, you just pull the result from cache and skip the XMLHttpRequest.
Because of the way axios interceptors work, the following snippet can be used to skip a certain XHR call conditionally:
// This should be the *last* request interceptor to add
axios.interceptors.request.use(function (config) {
/* check the cache, if hit, then intentionally throw
* this will cause the XHR call to be skipped
* but the error is still handled by response interceptor
* we can then recover from error to the cached response
**/
if (requestCache.isCached(config)) {
const skipXHRError = new Error('skip')
skipXHRError.isSkipXHR = true
skipXHRError.request = config
throw skipXHRError
} else {
/* if not cached yet
* check if request should be throttled
* then open up the cache to wait for a response
**/
if (requestCache.shouldThrottle(config)) {
requestCache.waitForResponse(config)
}
return config;
}
});
// This should be the *first* response interceptor to add
axios.interceptors.response.use(function (response) {
requestCache.setCachedResponse(response.config, response)
return response;
}, function (error) {
/* recover from error back to normality
* but this time we use an cached response result
**/
if (error.isSkipXHR) {
return requestCache.getCachedResponse(error.request)
}
return Promise.reject(error);
});

I have a similar problem, thru my research it seems to lack a good solution. All I saw were some ad hoc solutions so I open an issue for axios, hoping someone can answer my question https://github.com/axios/axios/issues/2118
I also find this article Throttling Axios requests but I did not try the solution he suggested.
And I have a discussion related to this My implementation of debounce axios request left the promise in pending state forever, is there a better way?

I finish one, #hackape thank you for you answer, the code is as follows:
const pendings = {}
const caches = {}
const cacheUtils = {
getUniqueUrl: function (config) {
// you can set the rule based on your own requirement
return config.url + '&' + config.method
},
isCached: function (config) {
let uniqueUrl = this.getUniqueUrl(config)
return caches[uniqueUrl] !== undefined
},
isPending: function (config) {
let uniqueUrl = this.getUniqueUrl(config)
if (!pendings[uniqueUrl]) {
pendings[uniqueUrl] = [config]
return false
} else {
console.log(`cache url: ${uniqueUrl}`)
pendings[uniqueUrl].push(config)
return true
}
},
setCachedResponse: function (config, response) {
let uniqueUrl = this.getUniqueUrl(config)
caches[uniqueUrl] = response
if (pendings[uniqueUrl]) {
pendings[uniqueUrl].forEach(configItem => {
configItem.isFinished = true
})
}
},
getError: function(config) {
const skipXHRError = new Error('skip')
skipXHRError.isSkipXHR = true
skipXHRError.requestConfig = config
return skipXHRError
},
getCachedResponse: function (config) {
let uniqueUrl = this.getUniqueUrl(config)
return caches[uniqueUrl]
}
}
// This should be the *last* request interceptor to add
axios.interceptors.request.use(function (config) {
// to avoid careless bug, only the request that explicitly declares *canCache* parameter can use cache
if (config.canCache) {
if (cacheUtils.isCached(config)) {
let error = cacheUtils.getError(config)
throw error
}
if (cacheUtils.isPending(config)) {
return new Promise((resolve, reject) => {
let interval = setInterval(() => {
if(config.isFinished) {
clearInterval(interval)
let error = cacheUtils.getError(config)
reject(error)
}
}, 200)
});
} else {
// the head of cacheable requests queue, get the response by http request
return config
}
} else {
return config
}
});

Related

fetch calls in react world: ReactJS

There is a requirement of cancelling the request calls when navigating away from the page or when the same api call is made multiple calls ( keeping the last one active).
This is how the API is extracted out( just a high level)
AJAX.ts
export async function customAjax(options){
let options = {};
options.headers = { ...options.headers, ...obj.headers };
const response = await fetch(url, options);
await response.json()
}
GET and POST calls are being extracted as
API.ts
const get = (url, extra = {}) => request({ url, type: "GET", ...extra });
const post = (url, payload, extra = {}) => request({ url, data: payload ,type: "POST",
}, ...extra });
In the react component I call these utilities as follows:
function MyComponent(){
useEffect(() => {
makeCall();
}, []);
async function makeCall(){
const { response, error } = await API.post(URL, payload);
// Handling code is not added here
// In the similar fashion GET calls are also made
}
}
I have come across Abortcontroller to cancel request where we could use abort method during unmounting of the component.
Is there a way to do this at a utililty level, may be inside customAjax so that I could avoid writing abort controller code everywhere?
From my understanding... What you describe is no different than a memory leak issue. And the current method for avoiding memory leaks is with the AbortController().
As far as handling this at the "utility level", I don't think this is feasible, and indeed would go against the preferred notion of an api being unaware of what's going on at the React component level; i.e separation of concerns..
So, in order to accomplish your requirement, you'll need to use AbortController(), or a custom implementation using a boolean flag that reflects whether the component is mounted, on a per component basis.
Using the boolean flag, you may be able to accept an argument in your api, passing the flag as a parameter; but again, I think this would be considered an anti-pattern.
I understand you're looking for a minimal implementation; but standard practice is fairly minimal:
useEffect(() => {
let abortController = new AbortController();
// Async code
return () => { abortController.abort(); }
}, []);
Using a boolean flag would be more verbose, and would entail something like this in your case:
useEffect(() => {
let isMounted = true;
customAjax(isMounted);
return () => {
isMounted = false;
}
}, []);
To handle out-of-order ajax responses, you can use a local variable inside the effect. For example,
useEffect(() => {
let ignore = false;
async function fetchProduct() {
const response = await fetch('http://myapi/product/' + productId);
const json = await response.json();
if (!ignore) setProduct(json);
}
fetchProduct();
return () => { ignore = true };
}, [productId]);
The ignore variable will ensure that only the latest request's response is updated to state. Reference - https://reactjs.org/docs/hooks-faq.html#performance-optimizations
Regarding memory leak concerns, please see this discussion - https://github.com/reactwg/react-18/discussions/82

How to synchronously serialize api calls in react?

I have a task that requires fetching api data, with the constraint of only one outstanding api request at a time. Must receive a response, or time out, before issuing the next one. Since fetch (or axios) returns a promise, I can’t figure out how to wait for each promise to fulfill before issuing the next fetch.
I'm handed a large array of api url's that must all be resolved in this one-at-a-time manner before continuing.
I’m using create-react-app’s bundled dev server, and Chrome browser.
Curiously, accomplishing this via a node script is easy, because ‘await fetch’ actually waits. Not so in my browser environment, where all the fetch requests blast out at once, returning promises along the way.
Here’s a simple loop that results in the desired behavior as a node script. My question is how to achieve this one-outstanding-request-at-a-time synchronous serialization in the browser environment?
const fetchOne = async (fetchUrl) => {
try {
const response = await fetch(fetchUrl, { // Or axios instead
"headers": {
'accept': 'application/json',
'X-API-Key': 'topSecret'
},
'method': 'GET'
})
const data = await response.json();
if (response.status == 200) {
return (data);
} else {
// error handling
}
} catch(error) {
// different error handling
}
}
const fetchAllData = async (fetchUrlArray) => {
let fetchResponseDataArray = new Array();
let fetchResponseDataObject = new Object(/*object details*/);
for (var j=0; j<fetchUrlArray.length; j++) { // or forEach or map instead
// Node actually synchronously waits between fetchOne calls,
// but react browser environment doesn't wait, instead blasts them all out at once.
// Question is how to achieve the one-outstanding-request-at-a-time synchronous
// serialization in the browser environment?
fetchResponseDataObject = await fetchOne(fetchUrlArray[j]);
fetchResponseDataArray.push(fetchResponseDataObject);
}
return(fetchResponseDataArray);
}
If there's a problem, it's with code you haven't shown (perhaps in one of your components, or maybe in your project configuration).
Here's an runnable example derived from the problem you described, which mocks fetch and an API, showing you how to iterate each network request synchronously (and handle potential errors along the way):
Note, handling potential errors at the boundaries where they might occur is a better practice than only having a top level try/catch: by doing so, you can make finer-grained decisions about what to do in response to each kind of problem. Here, each failed request is stored as [url, error] in a separate array so that you can programmatically make decisions if one or more requests failed. (Maybe you want to retry them in a subsequent step, or maybe you want to show something different in the UI, etc.). Note, there's also Promise.allSettled(), which might be useful to you now or in the future.
<div id="root"></div><script src="https://unpkg.com/react#17.0.2/umd/react.development.js"></script><script src="https://unpkg.com/react-dom#17.0.2/umd/react-dom.development.js"></script><script src="https://unpkg.com/#babel/standalone#7.16.4/babel.min.js"></script>
<script type="text/babel" data-type="module" data-presets="env,react">
const {useEffect, useState} = React;
const successChance = {
fetch: 0.95,
server: 0.95,
};
function mockApi (url, chance = successChance.server) {
// Simulate random internal server issue
const responseArgs = Math.random() < chance
? [JSON.stringify({time: performance.now()}), {status: 200}]
: ['Oops', {status: 500}];
return new Response(...responseArgs);
}
function mockFetch (requestInfo, _, chance = successChance.fetch) {
return new Promise((resolve, reject) => {
// Simulate random network issue
if (Math.random() > chance) {
reject(new Error('Network error'));
return;
}
const url = typeof requestInfo === 'string' ? requestInfo : requestInfo.url;
setTimeout(() => resolve(mockApi(url)), 100);
});
}
// Return an object containing the response if successful (else an Error instance)
async function fetchOne (url) {
try {
const response = await mockFetch(url);
if (!response.ok) throw new Error('Response not OK');
const data = await response.json();
return {data, error: undefined};
}
catch (ex) {
const error = ex instanceof Error ? ex : new Error(String(ex));
return {data: undefined, error};
}
}
async function fetchAll (urls) {
const data = [];
const errors = [];
for (const url of urls) {
const result = await fetchOne(url);
if (result.data) data.push([url, result.data]);
else if (result.error) {
// Handle this however you want
errors.push([url, result.error]);
}
}
return {data, errors};
}
function Example () {
const [data, setData] = useState([]);
const [loading, setLoading] = useState(false);
useEffect(() => {
const fetchData = async () => {
setLoading(true);
try {
const {data, errors} = await fetchAll([
'https://my.url/api/0',
'https://my.url/api/1',
'https://my.url/api/2',
'https://my.url/api/3',
'https://my.url/api/4',
'https://my.url/api/5',
'https://my.url/api/6',
'https://my.url/api/7',
'https://my.url/api/8',
'https://my.url/api/9',
]);
setData(data);
}
catch (ex) {
console.error(ex);
}
setLoading(false);
};
fetchData();
}, []);
return (
<div>
<div>Loading: {loading ? '...' : 'done'}</div>
<ul>
{
data.map(([url, {time}]) => (<li
key={url}
style={{fontFamily: 'monospace'}}
>{url} - {time}</li>))
}
</ul>
</div>
);
}
ReactDOM.render(<Example />, document.getElementById('root'));
</script>

Wait for axios response before doing anything else

I have the following function in my app.js:
window.SGN = require('./core/core');
SGN.importPermissions();
which comes from a home made package:
define('SGN',
['axios'],
function (axios) {
var SGN = {
importPermissions: () => {
axios
.get(`/admin/users/permissions`)
.then((response) => {
window.SGN.permissions = Object.values(response.data);
})
.catch((error) => {
console.log(error);
})
.then(() => {
});
}
}
return SGN;
}
);
However sometimes the rest of the application is run before that axios request is finished, how can I make it so that the application always waits for the request before everything else?
Although this looks like a duplicate question, I haven't found any answer that fixes this.
The rest of the application should get informed about when the asynchronous request has completed. For that to happen you should return the promise that you have created:
var SGN = {
importPermissions: () => {
return axios
// ^^^^^^
.get(`/admin/users/permissions`)
// ...etc
The rest of the application should be made dependent on the promise returned by SGN.importPermissions(), and so it could be like this:
SGN.importPermissions().then(() => {
// Anything that depends on the request should execute here,
// or be called from here
});

Crossdomain ServiceWorker load balancing

I'm trying to implement smth like crossdomain load balancing with ServiceWorker API.
My concept is:
After install on every request on fetch event I try to access main domain (https://example.com/)
If success I should return this to user with like event.respondWith(__response);
If failed (timed out or any other exception) I make CORS request to other server (https://balancer.com/) which returns other accessible domain (https://mirror1.example.com) and browser is redirected;
And I'm stucked on redirection step(((
So my current code is here
self.oninstall = function (event) {
event.waitUntil(self.skipWaiting());
};
self.onactivate = function (event) {
event.waitUntil(self.clients.claim());
};
self.initialUrl = false;
self.onfetch = async function (event) {
if (!self.initialUrl)
self.initialUrl = event.request.url;
if (self.initialUrl) {
event.respondWith(self.tryAccess(event))
} else {
event.respondWith(fetch(event.request));
}
};
self.tryAccess = async (event) => {
return new Promise(async (resolve, reject) => {
self.clients
.matchAll({type: 'window'})
.then(async (clients) => {
for (var i in clients) {
var _c = clients[0];
if (_c.url === event.request.url) {
try {
let __tryResponse = await fetch(event.request);
resolve(__tryResponse);
return;
} catch (e) {
let __json = await (await fetch("https://balancer.com/")).json();
return _c.navigate(__json.path).then(client => client.focus());
}
} else {
resolve();
}
}
});
});
};
Getting a reference to a WindowClient and forcibly changing its URL from inside of a fetch handler isn't the right way to redirect.
Instead, inside of your fetch handler, you can respond with a redirection response created by Response.redirect(). From the perspective of the browser, this will be treated just like any other redirection that might have originated from the server.
One thing to note is that if you initially request a subresource via a same-origin URL that results in a redirect to a cross-origin response, you might run into some issues. If your original requests are for cross-origin URLs and your potential redirects are also to cross-origin URLs, I think you'll be fine.
self.addEventListener('fetch', (event) => {
const fetchWithRedirection = async () => {
try {
// Use fetch(), caches.match(), etc. to get a response.
const response = await ...;
// Optional: also check response.ok, but that
// will always be false for opaque responses.
if (response) {
return response;
}
// If we don't have a valid response, trigger catch().
throw new Error('Unable to get a response.');
} catch (error) {
// Use whatever logic you need to get the redirection URL.
const redirectionURL = await ...;
if (redirectionURL) {
// HTTP 302 indicates a temporary redirect.
return Response.redirect(redirectionURL, 302);
}
// If we get to this point, redirection isn't possible,
// so just trigger a NetworkError.
throw error;
}
};
// You will probably want to wrap this in an if() to ensure
// that it's a request that you want to handle with redirection.
if (/* some routing criteria */) {
event.respondWith(fetchWithRedirection());
} else {
// Optionally use different response generation logic.
// Or just don't call event.respondWith(), and the
// browser will proceed without service worker involvement.
}
});

Axios cancel token cancelling request before even called

So I am implementing axios call cancelation in the project. Right now looking at axios documentation it seems pretty straight forward https://github.com/axios/axios#cancellation
So I did define variables on the top of my Vue component like
const CancelToken = axios.CancelToken;
const source = CancelToken.source();
obviously on top of that is import axios from 'axios';
Then I have a method of fetching the API
On the top of the method I want to cancel out the request in case it is running so the last one cancels out if the user spams the filtering.
async fetchPartners(inputToClear) {
source.cancel();
...
try {
const response = await axios.get(`../partners?limit=1000${this.createRequestString()}`, {
cancelToken: source.token
});
// Here you can see I did add the cancelToken to the request
this.partners = response.data.data;
} catch (error) {
if (axios.isCancel(error)) {
console.log('Request canceled', error.message);
}
const fetchErrors = this.utilGlobalHandleErrorMessages(error);
this.utilGlobalDisplayMessage(fetchErrors.message, { type: 'error' });
return [];
} finally {
...
}
},
So it is pretty straight forward, just took the code from axios documentation I gave you above, it should be working by logic. But what is actually happening, it doesn't even allow me to fetch the call, it is already cancelled out before I can call it. On console it shows me
Request canceled undefined
It just catches the error as if I am cancelling the call, but how can it be, because I am source.cancel() before the call.
Anyone has any idea?
I hope you should throttle your requests instead of canceling the request.
Could you please try the following if throttle does not suit your requirement?
const CancelToken = axios.CancelToken;
let source;
async fetchPartners(inputToClear) {
if(source){
source.cancel();
}
...
source = CancelToken.source();
try {
const response = await axios.get(`../partners?limit=1000${this.createRequestString()}`, {
cancelToken: source.token
});
// Here you can see I did add the cancelToken to the request
this.partners = response.data.data;
} catch (error) {
if (axios.isCancel(error)) {
console.log('Request canceled', error.message);
}
const fetchErrors = this.utilGlobalHandleErrorMessages(error);
this.utilGlobalDisplayMessage(fetchErrors.message, {
type: 'error'
});
return [];
} finally {
...
}
}

Categories