I have weird results displayed in the web console:
fetch() is sending duplicated requests to the same url.
I thought it could be something related to fetch(), but also noticed that on reload of the app (quasar, based on webpack) also the requests to the http://localhost:8080/sockjs-node/info are duplicated.
By contrast, I noticed that requests handled by jQuery are NOT duplicated and works fine.
I cannot say if it is an error due to webpack configuration, fetch or they way I am using it i Vue components.
E.g. This article points out possible causes https://insights.daffodilsw.com/blog/how-to-avoid-duplicate-api-requests but in my case it is not due to user interaction : requests are triggered at time of relaunching the app (webpack), and particularly the stack trace shows that the requests are fired at time of creating the components, just multiple times.
Example of how I am using fetch():
// component -
methods : {
search(input) {
return new Promise(resolve => { // a new promise is request multiple times, in spite in created() it is called just once
var _base = 'myEndpoint/api'
const url = `${_base}fuzzyautocomplete?q=${encodeURI(input)}`
if (input.length < 3) {
return resolve([])
}
fetch(url) // so promises are actually different, and duplicated requests are fired by fetch
.then(response => response.json())
.then(data => {
console.log(data)
// resolve(data.query.search)
resolve(data)
})
})
},
....
// and it should be called just once at time of creation
created() {
this.search('init first query !!');
}
Could you advise?
Related
I'm making a simple API in express js. I've an end point where I'll make a call to GitHub api int turn. My Front-end application will utilize it. Here is my code:
api.js
const express = require('express');
const router = express.Router();
...
var http = require('http');
var https = require("https");
router.get('/github', function (req, res) {
// APPROACH 1: Failed : fetch is not defined
// fetch('https://api.github.com/users/tmtanzeel')
// .then(response => response.json())
// .then(json => console.log(json))
// APPROACH 2: Failed : throw er; // Unhandled 'error' event
/*try {
https.get('https://api.github.com/users/tmtanzeel',function (res) {
console.log(res);
})
} catch (error) {
...
}*/
});
Both my approaches are failing. I've almost no experience with Express. Please picth in
The second method is almost corrent. Add the error handler and send to the caller the data you just received.
https.get('https://api.github.com/users/tmtanzeel',function (apiRes) {
apiRes.pipe(res);
}).on('error', (e) => {
console.error(e);
res.status(500).send('Something went wrong');
});
Handling the response (stream) received from the API call can be done in two ways.
Using pipes which is automatic
Handle read events and manage the data writing manually
I have used the first approach.
However, it is very well recommended that you get sound knowledge in handling Streams if you use Node JS. Streams are the basis of Node JS requests and responses.
https://nodejs.dev/learn/nodejs-streams
You should use Express to handle incoming requests.
(for example if your webapp fetches data from your (express) server).
Read the docs: http://expressjs.com
Your first attempt failed because fetch is an implementation of the web-browser, not one of nodejs.
If you want to use fetch try: https://www.npmjs.com/package/node-fetch
its a well documented, easy to use fetch function.
From your examples, all seems fine except I can't see you sending the returned data to the client.
You can try something similar like adding res.send(data) to send the data and make it available on the /github route
I would like to make two api call's at once to a ReST API in my vue component. I have done research online and am using this logic:
// Multiple fetches
Promise.all([
fetch(
`https://api.covid19api.com/live/country/${this.selected}/status/confirmed/date/${this.yesterday}`
),
fetch(
`https://api.covid19api.com/live/country/south-africa/status/confirmed/date/2020-03-21T13:13:30Z`
)
])
.then(responses => {
// Get a JSON object from each of the responses
return responses.map(response => {
return response.json();
});
})
.then(data => {
// Log the data to the console
// You would do something with both sets of data here
this.coronaVirusStats1 = data[0];
console.log(this.coronaVirusStats1);
})
.catch(function(error) {
// if there's an error, log it
console.log(error);
});
}
The consoled value is a promise which I understand but when I look in the Vue devTools under my component I see that coronaVirusStats1 has a value of "Promise", not the array of objects I expect back. When I do a single fetch and consume the data variable there is no problem. However I am perplexed as to how one accesses the returned data from fetch calls to multiple endpoints. I tried all the solutions here fetching api's ,but none worked. If someone can elucidate on the proper way to access the data from the fetches I would be most appreciative.
You're just about there. The issue is that your first then returns an array of promises. Unfortunately, promise chains only work with a Promise instance so there's nothing here that will wait for your promises to resolve.
The quick fix is to change the first then to
return Promise.all(responses.map(r => r.json()))
That being said, there's a little more to the fetch API, particularly for dealing with errors.
I would use something like the following for each fetch call to make sure network errors and non-successful HTTP requests are handled correctly.
This will also handle unwrapping the JSON response so you don't have to use the above
Promise.all([
fetch(url1).then(res => res.ok && res.json() || Promise.reject(res)),
fetch(url2).then(res => res.ok && res.json() || Promise.reject(res))
]).then(data => {
// handle data array here
})
See https://developer.mozilla.org/en-US/docs/Web/API/Response/ok
At work, we think about using Vuejs with Vuex for our frontend. I have already used it for private projects.
One of our big questions is the traffic. Our platform needs a lot of data, sometimes in large packages. Some of them are really big and it would be more expensive to load them more than once.
I've seen many examples of vue with vuex, but for me it looked like all the samples would request the same (already loaded) data every time they paged.
My real question is: Is there a way in vuejs or general to avoid or solve this problem? The only helpful thing I have found so far was this.
As far as I know, you can use this library https://github.com/kuitos/axios-extensions
An example here
import Axios from 'Axios';
import { throttleAdapterEnhancer } from 'axios-extensions';
const http = axios.create({
baseURL: '/',
headers: { 'Cache-Control': 'no-cache' },
adapter: throttleAdapterEnhancer(axios.defaults.adapter, { threshold: 2 * 1000 })
});
http.get('/users'); // make real http request
http.get('/users'); // responsed from the cache
http.get('/users'); // responsed from the cache
setTimeout(() => {
http.get('/users'); // after 2s, the real request makes again
}, 2 * 1000)
As you can see, you can create an adaptor and custom what you want. For example here, you keep the cache for only 2 seconds. So the first request to /users is a real one. The second and thirst request are cache, and the last one is after the two seconds, so it's a real one.
Can you be more specific about the context of how you will keep the cache. When do you need to reload the cache, after how many times, after which event, ...?
The strategy I use is to store the value on the Vuex state.
I write all my request in Vuex actions. In every action, I check if the data already exists on the Vuex state. If it does, I simply bypass the request and return the data from the state (saving requests from being called multiple times). If it doesn't exist, I'll make the request, then store the result on the Vuex state, and return the value.
Vuex Action:
getLists({ state, commit }) {
return new Promise((resolve, reject) => {
if (state.isSetLists === false) {
getListsFromServer((error, data) => {
if (error) {
reject(error);
} else {
console.log('call to getLists successful:', data);
commit('setLists', data.lists);
resolve(data.lists);
}
});
} else {
resolve(state.lists);
}
});
},
Then, the setLists mutation handles it like so:
setLists(state, lists) {
state.isSetLists = true;
state.lists = lists;
},
This way, the user can page around all they want, and only ever call each request once.
Im making a website with Nuxtjs, i want when i open any page of the website to get user information from the server using Axios, and i want to use these information to call another API's from the website.
For example: i will get the User id and Client id from the server and use them on the API URL, lets say i got User id = 5, Client id = 10
i will call another API's and use these informations
http://****/getItems?userid=5&clientid=10
Now my problem is the second API call before the first API finished so i didn't got the user informations yet.
Could you please help me with this issue, note that i want to get the user information on all pages. so if i reload the page in any page i want to get user informations.
So i call the user information API from a Layout and call the other API's from another components.
Thanks.
First you should use Axios module officially provided by Nuxt.js here, https://github.com/nuxt-community/axios-module. They have make the integration between Axios and Nuxt.js easier.
Axios uses promise so you can easily chaining method to do it. Let say you wanna get information from /get/product with data gotten from the url you mention before http://****/getItems?userid=5&clientid=10, you can easily do that like this
this.$axios.$get('/getItems?userid=5&clientid=10')
.then(data => {
// You can use your data received from first request here.
return this.$axios.$post('/get/product', {
id: data.id,
clientId: data.clientId
})
})
.then(data => {
// You can use your data received from second request here.
console.log(data)
})
Explanation
This part,
this.$axios.$get('/getItems?userid=5&clientid=10')
the axios will get the data from the url provided, when the data is received, we can use it within then() block as it accept callback as a parameter.
.then(data => {
// You can use your data received from first url here.
...
})
After that, if you wanna use your data you can easily return the axios request again with proper parameter you wanna send.
return this.$axios.$post('/get/product', {
id: data.id,
clientId: data.clientId
})
And again you can use the data received from second axios request within then() block.
.then(data => {
// You can use your data received from second request here.
console.log(data)
})
Updated
Oke, based on the clarification on the comment section below. We can return the axios promise in first action and then on the second method we can dispatch the first action,
actions: {
callFirst ({ commit }) {
return this.$axios.$get('/get/first')
.then(firstResult => {
commit('SET_FIRST', firstResult)
return firstResult
})
},
callSecond ({ dispatch, commit }) {
return dispatch('callFirst').then(firstResult => {
return this.$axios.$post(`/get/${firstResult.userId}`)
.then(secondResult => {
commit('SET_SECOND', secondResult)
return secondResult
})
})
}
}
Using that way, you just need to put the callSecond() action whereever you want get the second data. And you also don't need to put the callFirst() action on default.vue.
I'm new to service workers, and I'm using Workbox to precache my app shell and cache my api data.
The precaching of assets is working correctly, with the cache being created and populated.
The runtime caching isn't creating a cache and populating it until I reload the page a second time.
I thought this might be a timing issue, so I set a page reload of the data in the javascript, however this still didn't cache the call.
I'm not doing anything specific to create the cache, app code is:
...
app.getData = function() {
var requestHeaders = new Headers({
Accept: "application/json"
});
fetch(app.dataUrl, { headers: requestHeaders })
.then(function(response) {
return response.json();
})
.then(function(json) {
app.updateCards(json);
})
.catch(function(error) {
console.log('There has been a problem with your fetch operation: ' + error.message);
});
}
...
if ('serviceWorker' in navigator) {
navigator.serviceWorker
.register('/my_sw.js')
.then(function() {
console.log('Service Worker Registered');
});
}
app.getData(); # fetch api data
then in the service worker:
...
const workboxSW = new self.WorkboxSW({clientsClaim: true});
// register data url to cache
workboxSW.router.registerRoute(
'/my_api/data',
workboxSW.strategies.staleWhileRevalidate()
);
// pre-cache assets
workboxSW.precache(fileManifest);
I am using the Chrome Dev tools to check the sw status and the cache created. The network calls to the data URL are as follows:
1st load of page:
2nd load of page:
I'd be grateful for any advice on what I'm doing wrong, or how to debug it.
Thanks in advance
Dan
To be safe, you might want to add skipWaitingto the Workbox constructor to ensure the service worker doesn't wait for the page to reload to start caching.
You would also want to wait on serviceWorker.ready in your page before making the API call. This way you know the service worker is active.
These changes together, in your service worker you would have:
...
const workboxSW = new self.WorkboxSW({skipWaiting: true, clientsClaim: true});
// register data url to cache
workboxSW.router.registerRoute(
'/my_api/data',
workboxSW.strategies.staleWhileRevalidate()
);
// pre-cache assets
workboxSW.precache(fileManifest);
Then in your web page
...
if ('serviceWorker' in navigator) {
navigator.serviceWorker
.register('/my_sw.js')
.then(function() {
return navigator.serviceWorker.ready;
})
.then(function() {
app.getData(); # fetch api data
});
}