I'm new to vuejs I want to pass an JSON object to another component within same vue instance. following show the my code. from component add-user to component view-user. I tried vue props but it didn't work
Thank you very much.
Vue.component('view-users',{
props:['user'],
template: '<span>{{ user.name }}</span>'
});
Vue.component('add-user',{
data: function(){
return {
user:{
name:'jhon',
age:'29',
}
}
}
});
var app = new Vue({
el:'#app',
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.16/vue.min.js"></script>
<div id="app">
<add-user></add-user>
<view-users></view-users>
</div>
Props are mostly for passing data from parent components to child components, and a child component cannot directly modify the passed data and reflect the changes on parent components. In order to pass data around every component, a good way to do it is using Vuex.
First you create the state, possibly like
const state = {
user:{
name:'john',
age:'29',
}
}
And for the simplest case, that you are not doing anything asynchronous for now, you modify the state through mutations:
const mutations = {
CHANGE_NAME(state, payload) {
state.user.name = payload
},
CHANGE_AGE(state, payload) {
state.user.age = payload
}
}
With all these in place you can create the Vue store:
const store = new Vuex.Store({
state,
mutations
})
Then use it in your Vue instance:
const app = new Vue({
el: '...',
data: { ... },
store,
// ...
})
Finally, in your components, you can access and modify the state as follows:
Vue.component('my-component', {
data() {
return {
// ...
}
},
computed() {
user() {
// this is one way to do, you can also check out mapstate
return this.$store.state.user
}
},
methods: {
// you can also check out mapMutations
changeName(val) { this.$store.dispatch('CHANGE_NAME', val) },
changeAge(val) { this.$store.dispatch('CHANGE_AGE', val) },
}
})
Here's a simple example: http://jsfiddle.net/teepluss/zfab6tzp/6/
You can also use EventBus if you app is not too big (tutorial and documentation). And for Vuex, you can check out how to use state and mutations here.
If you use variable in many component, vuex could be better idea. But if you want to pass value to component, you can use like that
<div id="app">
<add-user :user=user></add-user>
<view-users :user=user></view-users>
</div>
import AddUser from '../add-user.vue'
import ViewUser from '../view-users.vue'
var app = new Vue({
el:'#app',
components: {
'add-user': AddUser,
'view-users': ViewUser
}
});
in view-user or add-user component you can declare like that
<template><span>{{ user.name }}</span></template>
<script>
export default {
props: {
user: {
type:'your type',
required: true/false
}
},
...
}
</script>
You can use simple external state management system.
Reference
Or you can use event handling to emit an event from one component and listen for the event in another component. Reference
Also have a look at this blog post regarding sharing data between components. Link
Related
I am trying to display a routerlink name based on a condition. I want to display the div section routerLink name if condition is true.If i check {{isNameAvailable}}, first it displays false and after this.names got the values it shows true.Since in the component getDetails() method is asynchronous this.names getting the values after html template render.Therefore this routerLink does n't display.Therefore I want to display div section after some time. (That 's the solution i have) Don't know whether is there any other solution.
This is my html file code.
<main class="l-page-layout ps-l-page-layput custom-scroll bg-white">
{{isNameAvailable}}
<div class="ps-page-title-head" >
<a *ngIf ="isNameAvailable === true" [routerLink]="['/overview']">{{Name}}
</a>
{{Name}}
</div>
</main>
This is my component.ts file
names= [];
isNameAvailable = false;
ngOnInit() {
this.getDetails()
}
getDetails() {
this.route.params.subscribe(params => {
this.names.push(params.Names);
console.log(this.names);
this.getValues().then(() => {
this.isNameAvailable = this.checkNamesAvailability(this.names);
console.log(this.isNameAvailable);
});
});
}
resolveAfterSeconds(x) {
return new Promise(resolve => {
setTimeout(() => {
resolve(x);
}, 900);
});
}
checkNamesAvailability(names) {
console.log(names);
return names.includes('Sandy');
}
async getValues() {
await this.resolveAfterSeconds(900);
}
And console.log(this.isLevelAvailable); also true. What I can do for this?
1.You do not have anything to show in the HTML only the isNameAvailable, because you do not have any assignment in the Name variable.
2.It is better to use the angular build-in async pipe,
when you want to show the returned value from observables.
3.When you are using the *ngIf directive you can skip *ngIf ="isNameAvailable === true" check because the variable is boolean type, you gust write *ngIf ="isNameAvailable", it will check also for null but NOT for undefined
It is working because the *ngIf directive is responsible for checking and rendering the UI, you can see how many times the directive is checking by calling an function and print and answer in the console.
By any chance do you have changeDetection: ChangeDetectionStrategy.OnPush docs set in component annotation? That might explain this behaviour. With it Angular run change detection only on component #Input()'s changes and since in your case there were non it did not run change detection which is why template was not updated. You could comment that line to check if that was cause of the issue. You are always able to run change detection manually via ChangeDetectorRef.detectChange() docs which should solve you problem
constructor(private cd: ChangeDetectorRef) {}
...
getDetails() {
this.route.params.subscribe(params => {
...
this.getValues().then(() => {
this.isNameAvailable = this.checkNamesAvailability(this.names);
this.cd.detectChanges(); // solution
console.log(this.isNameAvailable);
});
});
}
This stackblitz show this bug and solution. You can read more about change detection here
You could use RxJS timer function with switchMap operator instead of a Promise to trigger something after a specific time.
Try the following
import { Subject, timer } from 'rxjs';
import { takeUntil, switchMap } from 'rxjs/operators';
names= [];
isNameAvailable = false;
closed$ = new Subject();
ngOnInit() {
this.getDetails()
}
getDetails() {
this.route.params.pipe(
switchMap((params: any) => {
this.names.push(params.Names);
return timer(900); // <-- emit once after 900ms and complete
}),
takeUntil(this.closed$) // <-- close subscription when `closed$` emits
).subscribe({
next: _ => {
this.isNameAvailable = this.checkNamesAvailability(this.names);
console.log(this.isNameAvailable);
}
});
}
checkNamesAvailability(names) {
console.log(names);
return names.includes('Sandy');
}
ngOnDestroy() {
this.closed$.next(); // <-- close open subscriptions when component is closed
}
Context: I am trying to get Google Maps place data via the place_id on the beforeEnter() route guard. Essentially, I want the data to load when someone enters the url exactly www.example.com/place/{place_id}. Currently, everything works directly when I use my autocomplete input and then enter the route but it does not work when I directly access the url from a fresh tab. I've been able to solve this using the beforeEnter() route guard in traditional Vue, but cannot solve for this using Nuxt. Please help!
Question: How can I access the Vuex Store before a page loads in Nuxt?
Error: Any solution I try (see below) I either end up with a blank page or the page will not load (I think it is stuck in a loop and cannot resolve the Promise).
Attempted Solutions:
Using Middleware like below:
middleware({ store, params }) {
return store.dispatch('myModule/fetchLocation', params.id)
}
Using asyncData like below:
data(){
return{
filteredLocation: {}
}
}
// snip
async asyncData({ store, params }) {
const { data } = await store.dispatch('myModule/fetchLocation', params.id)
return filteredLocation = data
}
I tried looking into fetch, but apparently you no longer have access to context
Example Code:
In one of my store modules:
/* global google */
import Vue from 'vue'
import * as VueGoogleMaps from '~/node_modules/vue2-google-maps/src/main'
Vue.use(VueGoogleMaps, {
load: {
key: process.env.VUE_APP_GMAP_KEY,
libraries: 'geometry,drawing,places'
}
})
export const state = () => ({
selectedLocation: {}
})
export const actions = {
fetchLocation({ commit }, params) {
return new Promise((resolve) => {
Vue.$gmapApiPromiseLazy().then(() => {
const request = {
placeId: params,
fields: [
'name',
'rating',
'formatted_phone_number',
'geometry',
'place_id',
'website',
'review',
'user_ratings_total',
'photo',
'vicinity',
'price_level'
]
}
const service = new google.maps.places.PlacesService(
document.createElement('div')
)
service.getDetails(request, function(place, status) {
if (status === 'OK') {
commit('SET_PLACE', place)
resolve()
}
})
})
})
}
}
export const mutations = {
SET_PLACE: (state, selection) => {
state.selectedInstructor = selection
}
}
EDIT: I already have it in a plugin named google-maps.js and in my nuxt.config.js file I have:
plugins: [
{ src: '~/plugins/google-maps.js' }
]
//
//
build: {
transpile: [/^vue2-google-maps.js($|\/)/],
extend(config, ctx) {}
}
Using Middleware is how we can access Vuex before page loads. try putting the configuration part in a custom Nuxt plugin.
Create a file in Plugins folder (you can name it global.js).
Put this
import Vue from 'vue'
import * as VueGoogleMaps from '~/node_modules/vue2-google-maps/src/main'
Vue.use(VueGoogleMaps, {
load: {
key: process.env.VUE_APP_GMAP_KEY,
libraries: 'geometry,drawing,places'
}
})
in global.js.
Then add the plugin in nuxt.config.js like this.
plugins: [
'~/plugins/global.js'
]
Also, make sure you're using underscore before 'page_id' name in your folder structure.
I am creating a Spotify app with its API. I want 4 views (like '/', 'nowPlaying', 'favouriteArtists', 'favouriteSongs').
I need to setAccessToken for using functions like getMyCurrentPlaybackState() in every new page, right?. Idk if I need to if(params.access_token){spotifyWebApi.setAccessToken(params.access_token)} in every container that will use functions like getMyCurrentPlaybackState(). I was thinking of creating a Spotify.jsx container that handle the store of the Spotify Object (which is used in the token and in every container that use spotify functions). But with this Spotify.jsx i don't know either if it is a good approach nor how to connect its needed spotifyWebApi const to every container file and token file.
For better understanding of my idea: I would create a Token.jsx that has getHashParams() and a Playing.jsx that has getNowPlaying(). Every one needs the spotifyWebApi const.
import React, { Component } from 'react';
import Spotify from 'spotify-web-api-js';
const spotifyWebApi = new Spotify();
class App extends Component {
constructor(){
super();
const params = this.getHashParams();
this.state = {
loggedIn: params.access_token ? true : false,
nowPlaying: {
name: 'Not Checked',
image: ''
}
}
if (params.access_token){
spotifyWebApi.setAccessToken(params.access_token)
}
}
getHashParams() {
var hashParams = {};
var e, r = /([^&;=]+)=?([^&;]*)/g,
q = window.location.hash.substring(1);
while ( e = r.exec(q)) {
hashParams[e[1]] = decodeURIComponent(e[2]);
}
return hashParams;
}
getNowPlaying(){
spotifyWebApi.getMyCurrentPlaybackState()
.then((response) => {
this.setState({
nowPlaying: {
name: response.item.name,
image: response.item.album.images[0].url
}
})
})
}
}
Your title mentions Redux, but I don't see your code utilizing it. With Redux, you could get the access_token and then store it in state. This will allow you to use it in any Redux connected component.
Also, with Redux, you can use Redux Thunk (or similar) middleware that will allow you to use Redux actions to call an API. So then you would just write the different API calls as Redux actions, which would allow you to call them from any component, and have the results added to your Redux store (which again, can be used in any Redux connected component).
So, for example, your getNowPlaying() function could be an action looking something like this:
function getNowPlaying() {
return function (dispatch, getState) {
// get the token and init the api
const access_token = getState().spotify.access_token
spotifyWebApi.setAccessToken(access_token)
return spotifyWebApi.getMyCurrentPlaybackState().then((response) => {
dispatch({
type: 'SET_NOW_PLAYING',
name: response.item.name,
image: response.item.album.images[0].url
})
})
}
}
Note: You'll need to configure the Redux reducer for "spotify" (or however you want to structure your store) to store the data you need.
So, you could then call getNowPlaying() from any component. It stores the results in the redux store, which you could also use from any connected component. And you can use the same technique of getting the access_token from the store when needed in the actions.
Alternatively, if you didn't want to use Redux, you could provide context values to all child components, using React's Context features. You could do this with that token that each component would need in your setup. But Redux, in my opinion, is the better option for you here.
Instead of passing this const to other components, I would create a SpotifyUtils.jsx and inside it declare the const. And in this helper file I would export functions so other components can use them.
For example:
import Spotify from 'spotify-web-api-js';
const spotifyWebApi = new Spotify();
let token = null
export function isLoggedIn() {
return !!token
}
export function setAccessToke(_token) {
token = _token;
spotifyWebApi.setAccessToken(_token);
}
export function getNowPlaying(){
return spotifyWebApi.getMyCurrentPlaybackState()
.then((response) => {
return {
name: response.item.name,
image: response.item.album.images[0].url
}
})
}
So that in the components you can use them like so:
import React, { Component } from 'react';
import {
isLoggedIn,
setAccessToken,
getNowPlaying,
} from 'helpers/SpotifyUtils'
class App extends Component {
constructor(){
super();
this.state = {
loggedIn: isLoggedIn(),
nowPlaying: {
name: 'Not Checked',
image: ''
}
}
getHashParams() {
var hashParams = {};
var e, r = /([^&;=]+)=?([^&;]*)/g,
q = window.location.hash.substring(1);
while ( e = r.exec(q)) {
hashParams[e[1]] = decodeURIComponent(e[2]);
}
return hashParams;
}
componentDidMount() {
if (!this.state.loggedIn) {
const params = this.getHashParams();
if (params.access_token) {
setAccessToken(params.access_token)
getNowPlaying()
.then(nowPlaying => this.setState({ nowPlaying }))
}
}
}
}
This will enable your spotifyWebApi const to be reused in any component you import the helper functions. I am particularly found of this pattern, creating utils or helpers in a generic fashion so that you can reuse code easily. Also if spotify Web Api releases a breaking change, your refactor will be easier because you will only need to refactor the SpotifyUtils.jsx file since it will be the only file using import Spotify from 'spotify-web-api-js'
When using a generic modal or toast with a confirm button, it becomes useful to be able to pass an action into this component so it can be dispatched when you click confirm.
The action may look something like this:
export function showConfirm({modalConfirm}) {
return {
type: 'MODALS/SHOW_MODAL',
payload: {
modalId: getUuid(),
modalType: 'CONFIRM',
modalConfirm : modalConfirm,
},
};
}
Where modalConfirm is another action object such as:
const modalConfirm = {
type: 'MAKE_SOME_CHANGES_AFTER_CONFIRM',
payload: {}
}
The modalConfirm action is dispatched inside the modal component using dispatch(modalConfirm) or even dispatch(Object.assign({}, modalConfirm, someResultFromTheModal)
Unfortunatley this solution only works if modalConfirm is a simple redux action object. This system is clearly very limited. Is there anyway you can pass a function (such as a thunk) in instead of a simple object?
Ideally, something full featured likes this:
const modalConfirm = (someResultFromTheModal) => {
return (dispatch, getState){
dispatch({
type: 'MAKE_SOME_UPDATES',
payload: someResultFromTheModal
})
dispatch({
type: 'SAVE_SOME_STUFF',
payload: http({
method: 'POST',
url: 'api/v1/save',
data: getState().stuffToSave
})
})
}
}
Funny, putting an action object in the store and passing it as a prop to a generic dialog is exactly the approach I came up with myself. I've actually got a blog post waiting to be published describing that idea.
The answer to your question is "Yes, but....". Per the Redux FAQ at http://redux.js.org/docs/FAQ.html#organizing-state-non-serializable , it's entirely possible to put non-serializable values such as functions into your actions and the store. However, that generally causes time-travel debugging to not work as expected. If that's not a concern for you, then go right ahead.
Another option would be to break your modal confirmation into two parts. Have the initial modal confirmation still be a plain action object, but use a middleware to watch for that being dispatched, and do the additional work from there. This is a good use case for Redux-Saga.
I ended up using string aliases to an actions library that centrally registers the actions.
Modal emmiter action contains an object with functionAlias and functionInputs
export function confirmDeleteProject({projectId}) {
return ModalActions.showConfirm({
message: 'Deleting a project it permanent. You will not be able to undo this.',
modalConfirm: {
functionAlias: 'ProjectActions.deleteProject',
functionInputs: { projectId }
}
})
}
Where 'ProjectActions.deleteProject' is the alias for any type of complicated action such as:
export function deleteProject({projectId}) {
return (dispatch)=>{
dispatch({
type: 'PROJECTS/DELETE_PROJECT',
payload: http({
method: 'DELETE',
url: `http://localhost:3000/api/v1/projects/${projectId}`,
}).then((response)=>{
dispatch(push(`/`))
}),
meta: {
projectId
}
});
}
}
The functions are registered in a library module as follows:
import * as ProjectActions from '../../actions/projects.js';
const library = {
ProjectActions: ProjectActions,
}
export const addModule = (moduleName, functions) => {
library[moduleName] = functions
}
export const getFunction = (path) => {
const [moduleName, functionName] = path.split('.');
// We are getting the module only
if(!functionName){
if(library[moduleName]){
return library[moduleName]
}
else{
console.error(`Module: ${moduleName} could not be found.`);
}
}
// We are getting a function
else{
if(library[moduleName] && library[moduleName][functionName]){
return library[moduleName][functionName]
}
else{
console.error(`Function: ${moduleName}.${functionName} could not be found.`);
}
}
}
The modalConfirm object is passed in to the modal by props. The modal component requires the getFunction function in the module above. The modalConfirm object is transformed into a function as follows:
const modalConfirmFunction = (extendObject, modalConfirm) => {
const functionFromAlias = getFunction(modalConfirm.functionAlias);
if(functionFromAlias){
dispatch(functionFromAlias(Object.assign({}, modalConfirm.functionInputs, extendObject)));
}
}
As you can see, this function can take in inputs from the modal. It can execute any type of complicated action or thunk. This system does not break time-travel but the centralized library is a bit of a drawback.
I'm new to BackboneJS but I'm doing my best to learn it. I'm more familiar with AngularJS so I have some confusion in BackboneJS but would definitely want to become an expert BackboneJS developer too.
Back at my previous job, I was the frontend dev and I would work with the Java dev guy. We would have a meeting about how the JSON response would look like. Basically, I'll make a REST call(either with Restangular or $http) to one of their endpoints and I'll get a response. The JSON response will be assigned to a scope variable such as $scope.bookCollection. In my template, I'll just use ng-repeat to display it.
Now with BackboneJS, I'd like to do it properly. I read today that a BackboneJS Model is a container. What I'd like to happen is that after making a fetch(), I want the JSON response to be put in the Model that I defined. How is that done?
I found an example jsfiddle but I think it's a very bad example. I can't find something that is helpful right now, something with a good fetched data.
require.config({
paths: {
jquery: 'http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min',
underscore: 'http://underscorejs.org/underscore',
backbone: 'http://backbonejs.org/backbone-min'
},
shim: {
backbone: {
deps: ["underscore", "jquery"],
exports: "Backbone"
},
underscore: {
exports: "_"
}
}
});
require([
'jquery',
'underscore',
'backbone'], function ($, _, Backbone) {
var UserModel = Backbone.Model.extend({
urlRoot: '/echo/json/',
defaults: {
name: '',
email: ''
}
});
var userDetails = {
name: 'Nelio',
email: 'nelio#angelfire.com'
};
var user = new UserModel(userDetails);
user.fetch({
success: function (user) {
console.log(user.toJSON());
}
});
});
Here is the jsfiddle:
http://jsfiddle.net/20qbco46/
I want the JSON response to be put in the Model that I defined. How is
that done?
If you are trying to render the data from you model, you will use a view for this:
First, create a view to render your data:
// Create a new view class which will render you model
var BookView = Backbone.View.extend({
// Use underscores templating
template: _.template('<strong><%= title %></strong> - <%= author %>'),
initialize: function() {
// Render the view on initialization
this.render();
// Update the view when the model is changed
this.listenTo(this.model, "change", this.render);
},
render: function() {
// Render your model data using your template
this.$el.html(this.template(this.model.toJSON()));
return this;
}
});
See also: template and toJSON as well as $el
Next, create a Model:
// Create a model class
var Book = Backbone.Model.extend({
urlRoot: '/echo/json/',
defaults: {
title : '',
author: ''
},
});
Your model will hold the data fetched from the url / urlRoot
You can use set if you are trying to add new attributes to your model.
You can use get to grab attributes from your model.
See also - save and destroy.
Then, instantiate your model:
// Some dummy data
var instance = {
title: 'learn Backbone JS',
author: 'Bobby Longsocks',
};
// Instansite your model
var model = new Book(instance);
And finally, fetch your model data and create a new instance of you view:
// Fetch your model
model.fetch({
success: function(book) {
// Instansite your view, passing in your model
var view = new BookView({model: book, el: $('body')});
}
});
Here is an Example you can fiddle with.
And some further reading: Annotated Source