Develop Reference

How to pass Books array length to the parent component from child component in vue.js?

I am developing one page which is responsible from displaying books and the response is coming from backend API, DisplayBooks.vue component is imported inside a Dashboard.vue (parent-component).inside DisplayBooks.vue it contains books [] array , i want to pass this length to the Dashboard.vue component ,How to acheive this thing please help me to fix this thing..
Dashboard.vue
<template>
<div class="main">
<div class="navbar navbar-default navbar-fixed-top">
<div class="navbar-header">
<img src="../assets/education.png" alt="notFound" class="education-image" />
</div>
<ul class="nav navbar-nav">
<li>
<p class="brand">Bookstore</p>
</li>
</ul>
<div class="input-group">
<i #click="handlesubmit();" class="fas fa-search"></i>
<div class="form-outline">
<input type="search" v-model="name" class="form-control" placeholder='search...' />
</div>
</div>
<ul class="nav navbar-nav navbar-right" id="right-bar">
<li><a> <i class="far fa-user"></i></a></li>
<p class="profile-content">profile</p>
<li #click="shownComponent='Cart'"><a><i class="fas fa-cart-plus"></i></a></li>
<p class="cart-content" >cart <span class="length" v-if="booksCount">{{booksCount}}</span></p>
</ul>
</div>
<div class="mid-body">
<!-- i want to display books length here -->
<h6>Books<span class="items">({{books.length}})</span></h6>
<select class="options" #change="applyOption">
<option disabled value="">Sort by relevance</option>
<option value="HighToLow">price:High to Low</option>
<option value="LowToHigh">price:Low to High</option>
</select>
</div>
<div v-if="flam==false">
<h2>Hello</h2>
</div>
<DisplayBooks v-show="flag==='noOrder' && shownComponent==='DisplayBooks'" #update-books-count="(n)=>booksCount=n" />
<Cart v-show=" shownComponent==='Cart'" />
<sortBooksLowtoHigh v-show="flag==='lowToHigh'" #update-books-count="(n)=>booksCount=n" />
<sortBooksHightoLow v-show="flag==='highToLow'" #update-books-count="(n)=>booksCount=n" />
</div>
</template>
<script>
import sortBooksLowtoHigh from './sortBooksLowtoHigh.vue'
import sortBooksHightoLow from './sortBooksHightoLow.vue'
import DisplayBooks from './DisplayBooks.vue'
import Cart from './Cart.vue'
export default {
components: {
DisplayBooks,
sortBooksLowtoHigh,
sortBooksHightoLow,
Cart
},
data() {
return {
shownComponent:'DisplayBooks',
booksCount:0,
flag: 'noOrder',
brand: 'Bookstore',
name: '',
flam: true,
visible: true,
}
},
methods: {
flip() {
this.flam = !this.flam;
},
applyOption(evt) {
if (evt.target.value === "HighToLow") {
this.flag = 'highToLow';
} else this.flag = 'lowToHigh';
},
}
}
</script>
DisplayBooks.vue
<template>
<div class="carddisplay-section">
<!-- <div class="mid">
<h6>Books<span class="items">({{books.length}})</span></h6>
</div> -->
<div v-for="book in books" :key="book.id" class="card book" >
<div class="image-section" #mouseover="book.hover = true" #mouseleave="book.hover = false">
<div class="image-container">
<img v-bind:src="book.file" />
</div>
</div>
<div class="title-section" >
{{book.name}}
</div>
<div class="author-section">
by {{book.author}}
</div>
<div class="price-section">
Rs. {{book.price}}<label class="default">(2000)</label>
</div>
<div class="buttons">
<div class="button-groups" v-if="!addedBooks.includes(book.id)">
<button type="submit" #click="handleCart(book.id);toggle(book.id);addedBooks.push(book.id)" class="AddBag">Add to Bag</button>
<button class="wishlist">wishlist</button>
</div>
<div class="AddedBag" v-else>
<button class="big-btn" #click="removeFromCart(book.id);addedBooks=addedBooks.filter(id=>id!==book.id)">Added to Bag</button>
</div>
</div>
<div class="description" v-if="book.hover">
<p class="hovered-heading">BookDetails</p>
{{book.description}}
</div>
</div>
</div>
</template>
<script>
import service from '../service/User'
export default {
mounted() {
service.userDisplayBooks().then(response => {
let data = response.data;
data.map(function(obj) {
obj.hover = false;
return obj;
});
this.books.push(...data);
return response;
})
},
data() {
return {
isActive:true,
result: 0,
authorPrefix: 'by',
pricePrefix: 'Rs.',
defaultStrikePrice: '(2000)',
buttonValue: 'Add to Bag',
buttonWishlist:'wishlist',
buttonAddedBag:'Added to Bag',
flag: true,
state: true,
addedBooks:[],
clickedCard: '',
books: [] // i want to display this array length
}
},
watch:{
addedBooks:{
handler(val){
this.$emit('update-books-count',val.length)
},
deep:true
}
},
methods: {
toggleClass: function(event){
this.isActive = !this.isActive;
return event;
},
toggle(id) {
this.clickedCard = id;
console.log(this.clickedCard);
},
flip() {
this.state = !this.state;
},
Togglebtn() {
this.flag = !this.flag;
},
handleCart(bookId){
let userData={
id: bookId,
}
service.userUpdateCart(userData).then(response=>{
return response;
}).catch(error=>{
alert("error while displaying Books");
return error;
})
},
removeFromCart(bookId){
let userData={
id:bookId,
}
service.userRemoveFromCart(userData).then(response=>{
return response;
}).catch(error=>{
alert("error while removing from cart");
return error;
})
}
}
}
</script>

Bind element inside a for loop Vue not working properly

In the following Vue Component I want to loop through dwarfs array. And as long as I am in the current component, everything is fine (TEST) and also all the following properties are correct.
Currenct_Component.vue :
<template>
<div>
<h2>Stamm: {{ tribeName }}</h2>
<div class="card-container">
<div class="card" style="width: 18rem;" v-for="dwarf in dwarfs" :key="dwarf.name">
<!-- TEST -->
<p>{{dwarf}}</p>
<!-- CHILD COMPONENT -->
<app-modal
:showModal="showModal"
:targetDwarf="dwarf"
#close="showModal = false"
#weaponAdded="notifyApp"
/>
<!-- <img class="card-img-top" src="" alt="Card image cap">-->
<div class="card-body">
<h3 class="card-title" ref="dwarfName">{{ dwarf.name }}</h3>
<hr>
<ul class="dwarf-details">
<li><strong>Alter:</strong> {{ dwarf.age }}</li>
<li><strong>Waffen:</strong>
<ul v-for="weapon in dwarf.weapons">
<li><span>Name: {{ weapon.name }} | Magischer Wert: {{ weapon.magicValue }}</span></li>
</ul>
</li>
<li><strong>Powerfactor:</strong> {{ dwarf.weapons.map(weapon => weapon.magicValue).reduce((accumulator, currentValue) => accumulator + currentValue) }}</li>
</ul>
<button class="card-button" #click="showModal = true"><span class="plus-sign">+</span> Waffe</button>
</div>
</div>
</div>
<button id="backBtn" #click="onClick">Zurück</button>
</div>
</template>
<script>
import Modal from './NewWeaponModal.vue';
export default {
data() {
return {
showModal: false,
}
},
components: { appModal : Modal },
props: ['tribeName', 'dwarfs'],
methods: {
onClick() {
this.$emit('backBtn')
},
notifyApp() {
this.showModal = false;
this.$emit('weaponAdded');
}
},
}
</script>
But when I bind the element dwarf to the Child Component <app-modal/> it changes to the next dwarf in the array dwarfs (TEST) - (So as the result when i add a new weapon in the modal-form it gets added to the second dwarf...):
Child_Component.vue :
<template>
<div>
<div class="myModal" v-show="showModal">
<div class="modal-content">
<span #click="$emit('close')" class="close">×</span>
<h3>Neue Waffe</h3>
<!-- TEST -->
<p>{{ targetDwarf }}</p>
<form>
<input
type="text"
placeholder="Name..."
v-model="weaponName"
required
/>
<input
type="number"
placeholder="Magischer Wert..."
v-model="magicValue"
required
/>
<button #click.prevent="onClick">bestätigen</button>
</form>
</div>
</div>
</div>
</template>
<script>
export default {
data() {
return {
weaponName: '',
magicValue: '',
}
},
props: ['showModal', 'targetDwarf'],
methods: {
onClick() {
if(this.weaponName !== '' &&
Number.isInteger(+this.magicValue)) {
let newData = {...this.dwarf};
newData['weapons'] = [
...this.dwarf['weapons'],
{
"name": this.weaponName,
"magicValue": Number.parseInt(this.magicValue)
},
];
this.$http.post("https://localhost:5019/api", newData)
.then(data => data.text())
.then(text => console.log(text))
.catch(err => console.log(err));
this.$emit('weaponAdded');
} else {
alert('You should fill all fields validly')
}
},
}
}
</script>

It looks like you have the <app-modal/> component inside of the v-for="dwarf in dwarfs" loop, but then the control for showing all of the modal components created by that loop is just in one variable: showModal. So when showModal is true, the modal will show each of the dwarfs, and I'm guessing the second dwarf's modal is just covering up the first one's.
To fix this, you could move the <app-modal /> outside of that v-for loop, so there's only one instance on the page, then as part of the logic that shows the modal, populate the props of the modal with the correct dwarf's info.
Something like this:
<div class="card-container">
<div class="card" v-for="dwarf in dwarfs" :key="dwarf.name">
<p>{{dwarf}}</p>
<div class="card-body">
<button
class="card-button"
#click="() => setModalDwarf(dwarf)"
>
Waffe
</button>
</div>
</div>
<!-- Move outside of v-for loop -->
<app-modal
:showModal="!!modalDwarfId"
:targetDwarf="modalDwarfId"
#close="modalDwarfId = null"
#weaponAdded="onDwarfWeaponAdd"
/>
</div>
export default {
//....
data: () => ({
modalDwarfId: null,
)},
methods: {
setModalDwarf(dwarf) {
this.modalDwarfId = drawf.id;
},
onDwarfWeaponAdd() {
//...
}
},
}
You could then grab the correct dwarf data within the modal, from the ID passed as a prop, or pass in more granular data to the modal so it's more "dumb", which is the better practice so that the component isn't dependent on a specific data structure. Hope that helps

Courtesy of #Joe Dalton's answer, a bit alternated for my case:
<div class="card" style="width: 18rem;" v-for="dwarf in dwarfs" :key="dwarf.name">
...
<button class="card-button" #click="setModalDwarf(dwarf)"><span class="plus-sign">+</span> Waffe</button>
<div>
<app-modal
:showModal="showModal"
:targetDwarf="currentDwarf"
#close="showModal = false"
#weaponAdded="notifyApp"
/>
<script>
import Modal from './NewWeaponModal.vue';
export default {
data() {
return {
showModal: false,
currentDwarf: null,
}
},
components: { appModal : Modal },
props: ['tribeName', 'dwarfs'],
methods: {
setModalDwarf(dwarf) {
this.currentDwarf = dwarf;
this.showModal = true;
},
...
}
</script>

Vue : Accessing Nested Object Component's Values

I have problems accessing this "name" property on the component. I can only access it statically.
<template>
<div class="col-md-12">
<p
v-for="channel in channels"
:key="channel.id"
class="channel"
:class="{ 'active': channel.id == activeChannel }"
#click="setChannel(channel.id)">
{{ channel.users[0].name }}
</p>
</div>
</template>
Here is an Image of my Vue Devtools
So I have an v-for loop over channels, and I want to: Access the Usernames for each channel (if it is not my own preferably as "username" is set on my own i think its easy to exclude it right?) So that in the end In Channel 1 when there are 2 Users , I want to show the corresponding username, so the "other username", the one i am chatting with, and he should see my name that is the initial goal.
I thought of doing something like this:
<template>
<div class="col-md-12">
<p
v-for="channel in channels"
:key="channel.id"
class="channel"
:class="{ 'active': channel.id == activeChannel }"
#click="setChannel(channel.id)">
<!-- {{ channel.users[0].name }} -->
<span v-for="user,key in channel">{{key}}</span>
</p>
</div>
it at least displays the content of the channels object for each channel, but something like this isnt gonna work: key.user.name , unfortunately im stuck here. please help :)
edit: here is a dd() of the view
click
EDIT 2: Parent Data Provided:
//chat-app.blade.php
<div id="app">
<div class="container">
<div class="row">
<div class="col-md-8 col-md-offset-2">
<div class="panel panel-default">
<div class="panel-heading">Chats</div>
<vue-chat :channels="{{ $channels }}" ></vue-chat>
</div>
</div>
</div>
</div>
</div>
</div>
//<vue-chat> component
<template>
<div class="chat">
<div class="container">
<div class="row">
<div class="col-md-3">
<vue-chat-channels
:channels="channels"
:active-channel="activeChannel"
#channelChanged="onChannelChanged"
:username="sername"
></vue-chat-channels>
</div>
<div class="col-md-3">
<vue-chat-messages :messages="messages"></vue-chat-messages>
</div>
<div class="col-md-3">participants</div>
</div>
<div class="message-input-wrapper col-md-12"><vue-chat-new-message :active-channel="activeChannel"
:username="username"></vue-chat-new-message></div>
</div>
</div>
</template>
<script>
export default {
props: ["channels"],
data() {
return {
activeChannel: this.channels[0].id,
messages: [],
username: ''
};
},
methods: {
fetchMessages() {
let endpoint = `/channels/${this.activeChannel}/messages`;
axios.get(endpoint).then(({ data }) => {
this.messages = data;
});
},
onChannelChanged(id) {
this.activeChannel = id;
this.fetchMessages();
}
},
created() {
this.fetchMessages();
axios.get('/userfetch').then( ({data}) => {
console.log("Current User: "+data.name);
this.username = data.name;
});
console.log(this.channels[0].name);
// for (let channel of this.channels) {
this.channels.forEach(channel => {
// Channelname
window.Echo.channel('presence-'+channel.name)
.listen('MessageSent', (channel) => {
console.log(channel.data.message);
this.messages.push({ message: channel.data.message, author_username: channel.data.author_username});
if (this.activeChannel == channel.id) {
console.log("received message");
}
});
});
}
};
</script>
<style>
</style>
//ChatController.php
public function index()
{
$channels = Channel::with('users')->whereHas('users', function($q) {
$q->where('user_id',Auth::id());
})->get();
$user = Auth::user()->name;
return view('chat-app' , compact('channels','user'));
}
Short Explanation: ChatController returns the blade view, which has the data channels and user (my username) , and then vue comes into play which should pass down the prop of my username but i couldnt get it to work just yet

So you need to access users in every channel.
You can try like this:
<div class="col-md-12">
<p
v-for="channel in channels"
:key="channel.id"
class="channel"
:class="{ 'active': channel.id == activeChannel }"
#click="setChannel(channel.id)">
<span v-for="user in channel.users">
{{ user.name }}
</span>
</p>
</div>
This should work. If you have errors provide it here.
If you need to compare every user you can do it simply with v-if:
<span v-for="user in channel.users">
<span v-if="user.name === parentdata">
{{ user.name }}
</span>
</span>

Vue JS dynamic modal with components

in news.twig
{% extends 'layouts.twig' %}
{% block content %}
<section class="ls section_padding_bottom_110">
<div id="cart" class="container">
<cart
v-bind:materials="news"
type="news"
test="materials"
></cart>
<modal></modal>
</div>
<script type="text/x-template" id="modal-template">
<transition name="modal">
<div class="modal-mask" v-if="active" #click="close()">
<div class="modal-wrapper">
<div class="modal-container">
<div class="modal-header">
<h3>${ item.name }</h3>
</div>
<div class="modal-body">
${ item.body }
<br>
modal #${ item.id }
</div>
<div class="modal-footer">
<button class="modal-default-button" #click="close()">
close
</button>
</div>
</div>
</div>
</div>
</transition>
</script>
</section>
{% endblock %}
I have 2 components and 1 Vue in my js.
var Hub = new Vue();
Vue.component(
'modal', {
template: '#modal-template',
delimiters: ['${', '}'],
data: function() {
return {
active: false,
item: {
id: '',
name: '',
body: ''
}
}
},
methods: {
open: function (item) {
this.active = true;
this.item = item;
},
close: function () {
this.active = false;
}
},
mounted: function() {
this.$nextTick(function () {
Hub.$on('open-modal', this.open);
Hub.$on('close-modal', this.close);
}.bind(this));
}
});
Vue.component('cart', {
props: {
materials: { type: Array, required: true},
type: { type: String, required: true}
},
computed: {
isPoints() {
return this.type == 'paymentPoints';
},
isNews() {
return this.type == 'news';
}
},
template : `
<div class="row masonry-layout isotope_container">
<div class="col-md-4 col-sm-6 isotope-item" v-for="item in materials">
<div class="vertical-item content-padding topmargin_80">
<div class="item-media">
<img v-bind:src="item.image" alt="">
<div class="media-links p-link">
<div class="links-wrap">
<i class="flaticon-arrows-2"></i>
</div>
<a v-if="!isNews" v-bind:href="item.image" class="abs-link"></a>
</div>
</div>
<button #click="openModal(item)" #keyup.esc="closeModal()">more</button>
<div class="item-content with_shadow with_bottom_border">
<span v-if="isNews" class="categories-links" style="font-size:20px;">
<a rel="category" href="#modal1" data-toggle="modal">
{{item.name}}
</a>
</span>
<p>{{item.body}}</p>
<div v-if="isPoints">
<hr class="light-divider full-content-divider bottommargin_10">
<div class="media small-icon-media topmargin_5">
<div class="media-left">
<i class="fa fa-map-marker grey fontsize_18"></i>
</div>
<div class="media-body">
{{item.adress}}
</div>
</div>
<div class="media small-icon-media topmargin_5">
<div class="media-left">
<i class="fa fa-phone grey fontsize_18"></i>
</div>
<div class="media-body">
{{item.telephone}}
</div>
</div>
</div>
<div v-if="isNews" class="text-center">
<hr class="light-divider full-content-divider bottommargin_10">
<span class="date">
<i class="flaticon-clock-1 grey"></i>
<time class="entry-date">
{{item.date}}
</time>
</span>
</div>
</div>
</div>
</div>
</div>
`
});
var vm = new Vue({
el: '#cart',
name: 'cart',
delimiters: ['${', '}'],
data: {
complated: [],
continuing: [],
planned: [],
points: [],
infoSlider: [],
news: []
},
methods: {
openModal: function (item) {
Hub.$emit('open-modal', item);
},
closeModal: function () {
Hub.$emit('close-modal');
}
},
created() {
axios.get(url).then(res => {
var proje = res.data.projects[0];
this.complated = proje.complated;
this.continuing = proje.continuing;
this.planned = proje.planned;
this.points = res.data.paymentPoints;
this.infoSlider = res.data.sliderİnfos;
this.news = res.data.news;
})
.catch(e => {
console.log(e);
})
}
});
When I click openModal(item) button give me error ;
Property or method "openModal" is not defined on the instance but referenced during render. Make sure that this property is reactive, either in the data option, or for class-based components, by initializing the property. See: https://v2.vuejs.org/v2/guide/reactivity.html#Declaring-Reactive-Properties.
I can not use the openModal function in component.
I can use the function in news.twig without any problems, but then I can not use the component. Can you help me?

You are using openModal in cart component, but that method is defined in root component.
According to Vue's documentation:
Everything in the parent template is compiled in parent scope;
everything in the child template is compiled in the child scope.

in my case need to define variable in vuejs
like this
<script>
export default {
name: "MegaMenu",
props: {
categories: Array,
},
}

Passing data from parent component to a child component

I have a parent component as follows
<template>
<div class="row">
<mappings mapping-list="{{currentMappings}}"></mappings>
</div>
</template>
<script>
import Mappings from './content/Mappings.vue';
export default {
data () {
return {
currentMappings: Array
}
},
created () {
this.readData();
},
methods: {
readData () {
this.$http.get('data/Books.xml').then((response)=> {
var x2js = new X2JS();
var jsonObj = x2js.xml_str2json( response.body );
this.getMappings(jsonObj.WAStatus);
});
},
getMappings (jsonObj) {
this.currentMappings = jsonObj.WSSMappings;
}
},
components: { Mappings }
};
</script>
and a child "mappings" component as follows
<template>
<div class="col-lg-4">
<div class="hpanel stats">
<div class="panel-body h-200">
<div class="stats-title pull-left">
<h3>Mappings</h3>
</div>
<div class="stats-icon pull-right">
<img src="images/mappings.png" class="browserLogo">
</div>
<div class="m-t-xl">
<table class="table table-striped table-hover">
<tr v-for="mapping in mappingList ">
<td>name - {{$index}}</td>
</tr>
</table>
</div>
</div>
<div class="panel-footer">
Current WSS - SA Mappings
</div>
</div>
</div>
</template>
<script>
export default {
props: {
mappingList:Array
},
created () {
console.log(this.mappingList);
// console.log(this.$parent.mappings);
}
}
</script>
I am unable to pass data from the parent component to the child component. I am trying to use props here. The error that I am getting is
main.js:2756[Vue warn]: Invalid prop: type check failed for prop "mappingList". Expected Array, got String. (found in component: <mappings>)
Update
As per the suggestions made I have updated the parent component as follows
<template>
<div class="row">
<browser-stats></browser-stats>
</div>
<div class="row">
<mappings :mapping-list="currentMappings"></mappings>
</div>
</template>
<script>
import Mappings from './content/Mappings.vue';
export default {
data () {
return {
currentMappings: []
}
},
created () {
this.readData();
},
methods: {
readData () {
this.$http.get('data/WA_Status.xml').then((response)=> {
var x2js = new X2JS();
var jsonObj = x2js.xml_str2json( response.body );
this.getMappings(jsonObj.WAStatus);
});
},
getMappings (jsonObj) {
this.currentMappings = jsonObj.WSSMappings;
console.log(this.currentMappings.length);
console.log(JSON.stringify(this.currentMappings));
}
},
components: { Mappings }
};
</script>
and the child "mappings" component as follows
<template>
<div class="col-lg-4">
<div class="hpanel stats">
<div class="panel-body h-200">
<div class="stats-title pull-left">
<h3>Mappings</h3>
</div>
<div class="stats-icon pull-right">
<img src="images/mappings.png" class="browserLogo">
</div>
<div class="m-t-xl">
<table class="table table-striped table-hover">
<tr v-for="mapping in mappingList ">
<td>{{mapping._name}}</td>
</tr>
</table>
</div>
</div>
<div class="panel-footer">
Current WSS - SA Mappings
</div>
</div>
</div>
</template>
<script>
export default {
props: {
mappingList:[]
}
}
</script>
but I am getting an empty mappingList which means whenever I am doing console.log(this.currentMappings.length); I get undefined..
Can you please let me know what I am doing wrong here ?
Thanks

1) Fist issue
data () {
return {
currentMappings: Array
}
Should be
data () {
return {
currentMappings: []
}
2) Second issue
<mappings mapping-list="{{currentMappings}}"></mappings>
Should be:
<mappings :mapping-list="currentMappings"></mappings>
3) Third issue
created () {
console.log(this.mappingList);
// console.log(this.$parent.mappings);
}
This will return empty array every time. Because mappingList changed via AJAX and it's happed after created() was called. Try to use vue-devtool (chrome plugin) for better debug experience.
UPDATED:
To be able to watch async changes (like made with AJAX) consider to use watch this way:
{
data(){
//..
},
watch:{
'currentMappings'(val){
console.log('currentMappings updated', currentMappings);
}
}
}
Docs are here.

You use string interpolation ({{ }}) to try and pass the data to the prop - but the interpolation will turn the array into a string.
You should use a binding with v-bind
<mappings v-bind:mapping-list="currentMappings"></mappings>
...short form:
<mappings :mapping-list="currentMappings"></mappings>