I'm having a hard time passing Data (in this case userInfo-Token) from inside a beforeEach(to, from, next) Vue-Router middleware to the coressponding Vue-Component. I'm working on Vue-SinglePage components files as following:
App.js (entry Point)
<template>
<div id="app">
<Navigation/>
<router-view/>
<Footer/>
</div>
</template>
Router.js (router-view)
routes: [
{
path: '/',
meta: {requiresAuth: true}
}
]
router.beforeEach((to, from, next) => {
if(to.meta.requiresAuth){
// getting token form local storage
const token = localStorage.getItem('id_token');
// retrieving User Information
axios.defaults.headers.common['Authorization'] = "Bearer "+ token;
axios.post('http://localhost:4000/auth').then((result) => {
next(); // <-- how will the following component be able to work with the result?
}
}
}
Dashboard.js ('./' Component)
export default {
computed: {
welcomMsg: () => 'Hello ' + result.userName
}
}
What i did so far:
I tried a passing the userInfo from Entry-Point -> Router -> Component as properties. However it didnt work due to the information being asynchronos.
I tried to attach the data inside the beforeEach to the meta-Object. But I find myself unable to access the meta-Object inside the Component.
Maybe my approach is totally wrong. In this case: Is there a better way to pass the recieved UserData to Vue Components and make them avaliable there?
Thank you in advance.
I would handle this by using Vuex, which is a state management library.
You'd need to use create a Vuex module and add it to your root Vue instance like so:
const store = new Vuex.Store({
state: { userData: {} },
mutations: {
SET_USER_DATA: (state, data) => state.userData = data,
}
});
new Vue({ // your root Vue instance
el: '#app', // or whatever you've bound to root instance to
store, // the reference to the Vuex store
... // the rest of the root Vue definition
})
Now, the root Vue instance and all of its internal components will have a reference to the Vuex store via the $store property.
Then you can set the userData in you axios callback by calling store.commit, which will subsequently call the specified mutation in the Vuex Store (this would require that you also have the reference to the Vuex store object in this scope):
axios.post('http://localhost:4000/auth').then((result) => {
store.commit('SET_USER_DATA', result);
next();
});
And you can access the userData from any component via the $store object:
export default {
computed: {
welcomeMsg() {
let { userName } = this.$store.state.userData || {};
return (userName) ? 'Hello ' + userName : '';
}
}
}
notice I also updated the welcomeMsg computed to fix the spelling and to not use an arrow function
Related
I have some queries from an API-Server that returns a json object that will be static over a user session, but not static forever.
It's a one-pager with Vue router.
How can I achieve that I:
can access this.myGlobals (or similar eg window.myGlobals) in all components, where my prefetched json-data from API-Server is stored.
My approach that is already working is to embed help.js via a mixin.
Oddly enough, I get hundreds of calls to this query. At first I thought that it only happened in the frontend and is chached, but the requests are actually sent hundreds of times to the server. I think it is a mistake of my thinking, or a systematic mistake.
i think the problem is, that the helper.js is not static living on the vue instance
main.js:
import helpers from './helpers'
Vue.mixin(helpers)
helpers.js:
export default {
data: function () {
return {
globals: {},
}
}, methods: {
//some global helper funktions
},
}, mounted() {
let url1 = window.datahost + "/myDataToStore"
this.$http.get(url1).then(response => {
console.log("call")
this.globals.myData = response.data
});
}
}
log in console:
call
SomeOtherStuff
(31) call
SomeOtherStuff
(2) call
....
log on server:
call
call
call (pew pew)
My next idea would be to learn vuex, but since its a easy problem, im not sure if i really need that bomb ?
You can use plugin to achieve this.
// my-plugin.js
export default {
install (Vue, options) {
// start fetching data right after install
let url1 = window.datahost + "/myDataToStore"
let myData
Vue.$http.get(url1).then(response => {
console.log("call")
myData = response.data
})
// inject via global mixin
Vue.mixin({
computed: {
myData () {
return myData
}
}
})
// or inject via instance property
Vue.prototype.$myData = myData
// or if you want to wait until myData is available
Vue.prototype.$myData = Vue.$http.get(url1)
.then(response => {
console.log("call")
myData = response.data
})
}
}
and use it:
Vue.use(VueResource)
Vue.use(myPlugin)
I'm starting with Next.js and after going through docs, I cannot figure out how to get the route param code inside getStaticPaths method as shown below!?. code is not known before hand by any means and it can be anything.
I don't want to call api and get the data using useEffect inside the component.
File: pages/post/[code].js
import React from 'react';
import apiCall from 'api/something';
export default ({post}) => {
return <>
render components here based on prop `post`
</>
}
export async function getStaticPaths() {
// How to get [code] from the route here, which can be used below?
return {
paths: // NEED [code] HERE from current route,
fallback: false
}
}
export async function getStaticProps(ctx) {
return {
props: {
// [ctx.code] resolved from current route with the help of getStaticPaths,
post: apiCall(ctx.code)
}
}
}
I've tried getServerSideProps which works for me:
export const getServerSideProps = async (ctx) => {
return {
props: {
post: await apiCall(ctx.query.code)
}
};
};
But it fails when I do next export stating:
pages with getServerSideProps can not be exported. See more info here: https://err.sh/next.js/gssp-export
After investigating further on this error I found this solution, which is not feasible for me as my app is hosted on Heroku.
I'm trying to server-side render the html along with the data based on the route param code. But not able to do so now.
The purpose of the function getStaticPaths is to generate a list of paths for which static HTML will be rendered at build time. For example, for a list of 10 posts, you can generate 10 posts/[id] routes ahead of time if you know the id of the posts.
How getStaticPaths works with dynamic routes in more details..
Suppose you have a dynamic route /posts/[postId] if you choose to use static-generation you have to generate a list of paths that will include the postId as a route param and for each path returned, the function getStaticProps will be called to query the data at build time. Example,
// for /post/[postId]
export const getStaticPaths = async () => {
// if you know all the postId ahead of time
const paths = [
{ params: { postId: '1234' } }, // keep in mind postId has to be a string
{ params: { postId: '3792' } },
{ params: { postId: '1749' } },
]
return {
paths,
fallback: false // we are disabling fallback because we know all the paths ahead of time
}
}
// for each path returned getStaticProps will be called at build time
export const getStaticProps = async (context) => {
// you have access to the postId params that you returns from
// getStaticPaths here
const postId = context.params.postId
// now you can query the data from postId and return as props
return {
props: // queried data
}
}
If fallback is set to false any for any route path that is not returned from the function getStaticPaths nextjs will simply show a 404 error page.
How to use fallback: true to generate static pages for route params not known ahead of time
If you know some postId of the posts and the data for the posts do not change very often, you can choose to generate the pages with fallback property set to true, which will display a fallback version of the page for the paths that are not returned from the function getStaticPaths. And on request for the page nextjs will call getStaticProps and send the data as JSON which will be used to render the page in the browser.
Example,
// for /post/[postId]
export const getStaticPaths = async () => {
// you can get how many ever postIds are know ahead of time
// and return as paths with fallback set to true
const posts = // queried data from db or fetched from remote API
const paths = posts.map(post => { params:{ postId: post.id.toString() }})
return {
paths,
fallback: true
}
}
// in your page Component check for fallback and render a loading indicator
import { useRouter } from 'next/router';
const MyPage = (props) => {
// before you do anything
const router = useRouter();
if (router.isFallback) {
return <div>Loading....</div>
}
// rest of your page logic
}
If your data is very dynamic, let's say changing every 30mins or an hour or so. You can choose to use server-side rendering which will fetch the data on per request basis, but TTFB(time to first byte) will be higher. For example,
// for /post/[postId]
export const getServerSideProps = async (context) => {
// you also have access to the param postId from the context
const postId = context.params.postId
// query the data based on the postId and return as props
return {
props: // queried data
}
}
Keep in mind if you choose to go with getServerSideProps the function will be called on per-request basis so time to first byte will be higher.
Depending on use-cases you can also use static generation with client-side data fetching using swr from nextjs team repo link.
As I understand, you want to statically generate dynamic routes at build time.
To do so you need to let Next.js know what pages to generate, by specifying all codes.
export async function getStaticPaths() {
// you don't need here a code from current route
// but you need to specify all known post codes
return {
paths: [
{ params: { code: '1' } },
{ params: { code: '2' } },
{ params: { code: '3' } },
]
fallback: false
}
}
You would need to re-build app every time you change the posts.
Use getServerSideProps if you don't want to re-build project every time. Then the data would be fetched at request time. You can't export it because it requires Node.js server.
I'm developing a Promise-based modal component which provides the possibility of specifing a component as body of the modal itself. To achieve that result, I thought that a good solution would be using a dynamic component inside the modal template.
However, inside a NUXT application, if the component refers to the Vuex instance (this.$store), it turns out to be undefined (or better there is no $store object attribute). In the same way, any injection done inside plugins results undefined (e.g. inject('api', api) create the attribute $api, but it results undefined).
If I just use the component in the 'standard' way (e.g. placing it inside the page or another component template), everything works fine.
There should be some 'extra injection' that I should do before passing the component in a programmatic way.
Can anyone help me?
The NUXT project structure (simplified):
/pages/index.vue
/plugins/api.js
/store/auth.js
/components/HelloComponent.vue
/plugins/api.js
let api = {}
api.call = function (request, auth, unpack, axios = this.axios) {
if (!request) Error('backend.js:call invalid params:', request, auth, unpack, axios)
if (auth) {
if (request.headers)
request.headers['Authorization'] = 'Bearer ' + this.auth.accessToken
else
request.headers = { 'Authorization': 'Bearer ' + this.auth.accessToken }
}
return axios(request).then((response) => unpack ? response.data : response)
}
api.getAPI = function (api, params, auth = true, unpack = true) {
if (!api) Error('api.js:getAPI invalid params:', api)
console.log('api.js:getAPI api:', api)
return this.call({ method: 'get', url: api, params: params }, auth, unpack)
}
api.postAPI = function (api, params, data, auth = true, unpack = true) {
if (!api) Error('api.js:postAPI invalid params:', api, data)
console.log('api.js:postAPI api:', api)
return this.call({ method: 'post', url: api, params: params, data: data }, auth, unpack)
}
/*******************************************************/
/* NUXT plugin and reference injection */
/*******************************************************/
export default function (context, inject) {
console.log('[CALL] api.js')
/* assign global $axios instance */
api.axios = context.$axios
/* assign auth instance to access tokens */
api.auth = context.store.state.auth
/* inject backend reference into application instance */
inject('api', api)
}
/pages/index.vue
<template>
<div>
<span>
{{ $store.auth.state.name }} // -> Displays 'Chuck'
</span>
/* Object.keys(this).includes('$store): false'; Object.keys(this).includes('$auth): true' */
<component :is="cComponent" /> // -> this.$store is undefined; auth: undefined
<hello-component /> // -> Displays 'Chuck'; auth: Object {...}
</div>
</template>
<script>
import HelloComponent from '../components/HelloComponent.vue'
export default {
components: {
HelloComponent
},
created () {
this.$store.commit('auth/setName', 'Chuck')
},
computed: {
cComponent () {
return HelloComponent
}
}
}
</script>
/components/HelloComponent.vue
<template>
<span>
{{ $store.auth.state.name }}
</span>
</template>
<script>
export default {
created() {
console.log('auth:', this.$auth)
}
}
</script>
/store/auth.js
export const state = () => ({
accessToken: null,
refreshToken: null,
name: null,
})
export const mutations = {
setAccessToken(state, token) {
console.info('auth.js:setAccessToken', token)
state.accessToken = token
},
setRefreshToken(state, token) {
console.info('auth.js:setRefreshToken', token)
state.refreshToken = token
},
setName(state, name) {
console.info('auth.js:setName', name)
state.user = name
},
}
if you have no access of this pointer in Nuxt project, And you really need to access store, then simply use
window.$nuxt.$store instead of this.$store;
Hope it will solve your problem
I am working on a project and using Vue.js for the frontend. I have following code in the main.js file.
new Vue({ // eslint-disable-line no-new
//el: '#app',
router,
data () {
return {
friends: []
}
},
methods: {
getFriends: function () {
return this.friends;
}
},
created: function () {
this.$http.get('/user/' + this.getUserIDCookie('userID') +
'/friends').then(function (response) {
this.friends = response.data;
});
},
components: {
'nav-bar': require('./components/Navigation.vue')
},
template: `
<div id="app">
<nav-bar></nav-bar>
<router-view class="router-view"></router-view>
</div>`
}).$mount('#app');
In one of the pages(for ex. when the page is redirected to localhost/#/user/1/details, I am retrieving the friends' list from main.js like below:
<script type="text/babel">
export default {
name: 'profile',
data: function () {
return {
user: {},
friends: []
}
},
methods: {
// Some methods
},
created: function () {
this.friends = this.$root.getFriends();
}
}
</script>
The problem arises when I refresh the current page. After page refresh, this.friends is null/undefined because this.$root.getFriends() is returning null/undefined. I can move it to user component, but I want to keep it in main.js so that GET call is used once and data will be available to the whole application.
Any input regarding how to solve this issue would be great. I am using Vue 2.0.1
Really, what you want to do, is pass the data the component needs as props.
The dirt simple easiest way to do it is this.
<router-view class="router-view" :friends="friends"></router-view>
And in your profile component,
export default {
props:["friends"],
name: 'profile',
data: function () {
return {
user: {},
friends: []
}
},
methods: {
// Some methods
}
}
If you want to get more sophisticated, the later versions of VueRouter allow you to pass properties to routes in several ways.
Finally, there's always Vuex or some other state management tool if your application gets complex enough.
The problem is that when you refresh the page, the whole app reloads, which includes the get, which is asynchronous. The router figures out that it needs to render details, so that component loads, and calls getFriends, but the asynchronous get hasn't finished.
You could work around this by saving and pulling the Promise from the get, but Bert's answer is correct: the Vue Way is to send data as props, not to have children pull it from parents.
I'm attempting to watch for localstorage:
Template:
<p>token - {{token}}</p>
Script:
computed: {
token() {
return localStorage.getItem('token');
}
}
But it doesn't change, when token changes. Only after refreshing the page.
Is there a way to solve this without using Vuex or state management?
localStorage is not reactive but I needed to "watch" it because my app uses localstorage and didn't want to re-write everything so here's what I did using CustomEvent.
I would dispatch a CustomEvent whenever you add something to storage
localStorage.setItem('foo-key', 'data to store')
window.dispatchEvent(new CustomEvent('foo-key-localstorage-changed', {
detail: {
storage: localStorage.getItem('foo-key')
}
}));
Then where ever you need to watch it do:
mounted() {
window.addEventListener('foo-key-localstorage-changed', (event) => {
this.data = event.detail.storage;
});
},
data() {
return {
data: null,
}
}
Sure thing! The best practice in my opinion is to use the getter / setter syntax to wrap the localstorage in.
Here is a working example:
HTML:
<div id="app">
{{token}}
<button #click="token++"> + </button>
</div>
JS:
new Vue({
el: '#app',
data: function() {
return {
get token() {
return localStorage.getItem('token') || 0;
},
set token(value) {
localStorage.setItem('token', value);
}
};
}
});
And a JSFiddle.
The VueJs site has a page about this.
https://v2.vuejs.org/v2/cookbook/client-side-storage.html
They provide an example.
Given this html template
<template>
<div id="app">
My name is <input v-model="name">
</div>
<template>
They provide this use of the lifecycle mounted method and a watcher.
const app = new Vue({
el: '#app',
data: {
name: ''
},
mounted() {
if (localStorage.name) {
this.name = localStorage.name;
}
},
watch: {
name(newName) {
localStorage.name = newName;
}
}
});
The mounted method assures you the name is set from local storage if it already exists, and the watcher allows your component to react whenever the name in local storage is modified. This works fine for when data in local storage is added or changed, but Vue will not react if someone wipes their local storage manually.
Update: vue-persistent-state is no longer maintained. Fork or look else where if it doesn't fit your bill as is.
If you want to avoid boilerplate (getter/setter-syntax), use vue-persistent-state to get reactive persistent state.
For example:
import persistentState from 'vue-persistent-state';
const initialState = {
token: '' // will get value from localStorage if found there
};
Vue.use(persistentState, initialState);
new Vue({
template: '<p>token - {{token}}</p>'
})
Now token is available as data in all components and Vue instances. Any changes to this.token will be stored in localStorage, and you can use this.token as you would in a vanilla Vue app.
The plugin is basically watcher and localStorage.set. You can read the code here. It
adds a mixin to make initialState available in all Vue instances, and
watches for changes and stores them.
Disclaimer: I'm the author of vue-persistent-state.
you can do it in two ways,
by using vue-ls and then adding the listener on storage keys, with
Vue.ls.on('token', callback)
or
this.$ls.on('token', callback)
by using storage event listener of DOM:
document.addEventListener('storage', storageListenerMethod);
LocalStorage or sessionStorage are not reactive. Thus you can't put a watcher on them. A solution would be to store value from a store state if you are using Vuex for example.
Ex:
SET_VALUE:(state,payload)=> {
state.value = payload
localStorage.setItem('name',state.value)
or
sessionStorage.setItem('name',state.value)
}