Develop Reference

Vue.js : Passing Props Down to Child Components to Update Styles in the DOM

I'm a beginner trying to get my app to pass props that set CSS styles down a chain to child components. I have a listener that checks for view port size, and as the window gets resized, it checks past a certain point and then swaps the css class and passes it down the chain..
I think I may be doing something incorrectly because my child components don't seem to be receiving the new styles and aren't updating in the DOM as I drag the window.
Here is my code.. I removed irrelevant code to make it easier to read:
Page_Listings.vue
<template>
<main>
<section>
<ListingRack
:prp_classes="rackClass"
/>
</section>
</main>
</template>
<script>
import ListingRack from './Listing__Rack.vue';
export default {
name: 'Front_Page__Panel',
data() {
return {
viewportWidth: window.innerWidth
}
},
methods: {},
mounted() { window.onresize = () => this.viewportWidth = window.innerWidth },
components: {ListingRack},
},
computed: {
rackClass: function(){
let theValue;
console.log('>> viewport width is now: ',this.viewportWidth)
if(this.viewportWidth > 1200) {
theValue = "grid_view";
console.log('>> grid view')
}
else {
theValue = 'card_view';
console.log('>> card view')
}
return theValue
}
}
}
</script>
Listing__Rack.vue
<template>
<div class="listing_rack" :class="classes">
<ul>
<li v-for="item in listings" :key="item.postId">
// I removed irrelevant code for hte sake of simplicity in this example.
// listings is a GraphQL returned array of data that generates a list of "listings".
<Listing
:prp_classes=classes
/>
</li>
</ul>
</div>
</template>
<script>
import Listing from './Listing.vue'
export default {
name: 'listing__rack',
data() {
return {
posts: [], // what we get from the database.
listings: [], // what we copy from the database.
classes: this.prp_classes
}
},
props: {
prp_classes: String
},
components: {
Listing
},
watch: {
classes: function(){
//just to check if we're receiving anything...
console.log(">> [Listing_Rack](watch)(classes) there was a change to classes!");
}
}
}
</script>
Listing.vue
<template>
<div :id=id
:class=classes
class="listing"
:style="backgroundStyle"
>
</div>
</template>
<script>
export default {
name: 'Listing',
data() {
return {
classes: this.prp_classes,
backgroundStyle: String
}
},
props: {
prp_classes: String
},
methods: {
checkClasses: function(){
if(this.classes === 'grid_view') this.backgroundStyle = 'background: center / cover no-repeat url(background.jpg);';
}
},
mounted: function() {
this.checkClasses();
},
watch: {
classes: function(){
this.checkClasses();
}
}
}
</script>
My console.logs on rackClass so I know the class swapping part is working, but all my subsequent child components don't seem to be updating accordingly..
Can someone tell me what I'm doing wrong? Is there a better way to do this? How come my props aren't being passed when I drag the window, and how can I dynamically set styles in the DOM?

Your code does not work because of the one big mistake (don't worry, many people do it)
You are passing your classes using props to child components. But instead of using this prop (prp_classes) directly in the child's template, you create an absolutely unnecessary classes property in the data()
Problem with that is that data() is executed only once when the component is created. If the value of the prp_classes prop changes later, classes property from the data() just holds the old value.
To fix this, remove unnecessary classes from the data and use the prop directly in the template...
...bit more explanation by example what is going on:
let prp_classes = 'card_view'
let classes = prp_classes
prp_classes = 'grid_view'
// prp_classes === 'grid_view', classes === 'card_view', prp_classes !== classes
// strings/numbers/Date ...all work the same
let o1 = { a: 1 }
let o2 = o1
o1.a = 2
// o1.a === 2, o2.a === 2, o1 === o2
More to study

Advanced Vue.js Dynamic Functional Component using `:is` syntax and render function

Background: I've built a standard single file component that takes a name prop and looks in different places my app's directory structure and provides the first matched component with that name. It was created to allow for "child theming" in my Vue.js CMS, called Resto. It's a similar principle to how WordPress looks for template files, first by checking the Child theme location, then reverting to the parent them if not found, etc.
Usage : The component can be used like this:
<!-- Find the PageHeader component
in the current child theme, parent theme,
or base components folder --->
<theme-component name="PageHeader">
<h1>Maybe I'm a slot for the page title!</h1>
</theme-component>
My goal : I want to convert to a functional component so it doesn't affect my app's render performance or show up in the Vue devtools. It looks like this:
<template>
<component
:is="dynamicComponent"
v-if="dynamicComponent"
v-bind="{ ...$attrs, ...$props }"
v-on="$listeners"
#hook:mounted="$emit('mounted')"
>
<slot />
</component>
</template>
<script>
import { mapGetters } from 'vuex'
export default {
name: 'ThemeComponent',
props: {
name: {
type: String,
required: true,
default: '',
},
},
data() {
return {
dynamicComponent: null,
resolvedPath: '',
}
},
computed: {
...mapGetters('site', ['getThemeName']),
customThemeLoader() {
if (!this.name.length) {
return null
}
// console.log(`Trying custom theme component for ${this.customThemePath}`)
return () => import(`#themes/${this.customThemePath}`)
},
defaultThemeLoader() {
if (!this.name.length) {
return null
}
// console.log(`Trying default component for ${this.name}`)
return () => import(`#restoBaseTheme/${this.componentPath}`)
},
baseComponentLoader() {
if (!this.name.length) {
return null
}
// console.log(`Trying base component for ${this.name}`)
return () => import(`#components/Base/${this.name}`)
},
componentPath() {
return `components/${this.name}`
}, // componentPath
customThemePath() {
return `${this.getThemeName}/${this.componentPath}`
}, // customThemePath()
},
mounted() {
this.customThemeLoader()
.then(() => {
// If found in the current custom Theme dir, load from there
this.dynamicComponent = () => this.customThemeLoader()
this.resolvedPath = `#themes/${this.customThemePath}`
})
.catch(() => {
this.defaultThemeLoader()
.then(() => {
// If found in the default Theme dir, load from there
this.dynamicComponent = () => this.defaultThemeLoader()
this.resolvedPath = `#restoBaseTheme/${this.defaultThemePath}`
})
.catch(() => {
this.baseComponentLoader()
.then(() => {
// Finally, if it can't be found, try the Base folder
this.dynamicComponent = () => this.baseComponentLoader()
this.resolvedPath = `#components/Base/${this.name}`
})
.catch(() => {
// If found in the /components dir, load from there
this.dynamicComponent = () => import(`#components/${this.name}`)
this.resolvedPath = `#components/${this.name}`
})
})
})
},
}
</script>
I've tried SO many different approaches but I'm fairly new to functional components and render functions (never got into React).
The roadblock : I can't seem to figure out how to run the chained functions that I call in my original mounted() function. I've tried running it from inside the render function with no success.
Big Question
How can I find and dynamically import the component I'm targeting before I pass that component to the createElement function (or within my single file <template functional><template/>)?
Thanks all you Vue-heads! ✌️
Update: I stumbled across this solution for using the h() render function and randomly loading a component, but I'm not sure how to make it work to accept the name prop...

Late to the party, but I was in a similar situation, where I had a component in charge of conditionally render one of 11 different child components:
<template>
<v-row>
<v-col>
<custom-title v-if="type === 'title'" :data="data" />
<custom-paragraph v-else-if="type === 'paragraph'" :data="data" />
<custom-text v-else-if="type === 'text'" :data="data" />
... 8 more times
</v-col>
</v-row>
</template>
<script>
export default {
name: 'ProjectDynamicFormFieldDetail',
components: {
CustomTitle: () => import('#/modules/path/to/CustomTitle'),
CustomParagraph: () => import('#/modules/path/to/CustomParagraph'),
CustomText: () => import('#/modules/path/to/CustomText'),
... 8 more times
},
props: {
type: {
type: String,
required: true,
},
data: {
type: Object,
default: null,
}
},
}
</script>
which of course is not ideal and pretty ugly.
The functional equivalent I came up with is the following
import Vue from 'vue'
export default {
functional: true,
props: { type: { type: String, required: true }, data: { type: Object, default: null } },
render(createElement, { props: { type, data } } ) {
// prop 'type' === ['Title', 'Paragraph', 'Text', etc]
const element = `Custom${type}`
// register the custom component globally
Vue.component(element, require(`#/modules/path/to/${element}`).default)
return createElement(element, { props: { data } })
}
}
Couple of things:
lazy imports don't seem to work inside Vue.component, hence require().default is the way to go
in this case the prop 'type' needs to be formatted, either in the parent component or right here

Building a form with Vuejs. Pass data from children to parent

I'm trying to build a form using "v-for" for input component and then generate a pdf file with PDFMake using data from inputs. But I didn't know how to pass the data from input component back to parent.
I read a lot of topics, but can't find a way to do this.
Here is short code without additional inputs, checkboxes etc. I plan to use around 15 inputs with different parameters to generate final PDF. Some of parameters also will be used to change final data depending of conditional statements.
Everything is work fine if code in one file, without loop and components. But not now.
Here is parent:
<template lang="pug">
.form
Input(v-for="data in form.client_info" v-bind:key="data.id" v-bind:data="data")
button(#click="pdfgen") Download PDF
</template>
<script>
export default {
components: {
Input: () => import('#/components/items/form/input')
},
data() {
return {
client_name: '',
client_email: '',
form: {
client_info: [
{id:'client_name', title:'Name'},
{id:'client_email', title: 'Email'},
{id:'foo', title: 'foo'}
],
}
}
},
methods: {
pdfgen: function () {
var pdfMake = require('pdfmake/build/pdfmake.js')
if (pdfMake.vfs == undefined) {
var pdfFonts = require('pdfmake/build/vfs_fonts.js')
pdfMake.vfs = pdfFonts.pdfMake.vfs;
}
if (this.foo) {
var foo = [
'Foo: ' + this.foo
];
} else {
foo = ''
]
}
var docDefinition = {
content: [
'Name: ' + this.client_name,
'Email: ' + this.client_email,
'\n',
foo
]
}
pdfMake.createPdf(docDefinition).download('Demo.pdf');
}
}
}
</script>
Here is a children (Input component):
<template lang="pug">
label.form_item
span.form_item_title {{ data.title }}
input.form_item_input(:v-model="data.id" type="text")
</template>
<script>
export default {
props: ['data']
}
</script>
Any ideas how to make it work?

You'll want to use a method that vue has build-in named $emit().
Before going into how to do that, a quick explanation. Because vue attempts to make data flow one-directional there is not a super quick way to just pass data back to a parent. What Vue proposes instead is to pass a method to the child component that, when called, will 'emit' the value it changed to it's parent and the parent can then do what it wants with that value.
So, in your parent component you'll want to add a method that will handle a change when the child emits. This could look something like:
onChildValueChanged(value){ this.someValue = value }
The value we passed to the function will be coming from our child component. We will need to define in our child component what this function should do. In your child component you could have a function that looks like so:
emitValueChange(event){ this.$emit('childFunctionCall', this.someChildValue) }
Next we need to tie those two functions together by adding an attribute on our child template. In this example that might look like:
<Child :parentData="someData" v-on:childFunctionCall="onChildValueChanged"></Child>
What that above template is doing is saying that when the function on:childFunctionCall is 'emited' then our function in the parent scope should fire.
Finally, in the child template we just need to add some event that calls out emiter. That could look like:
<button v-on:click="emitToParent">This is a button</button>
So when our button is clicked, the emiter is called. This triggers the function in our child component named 'emitToParent' which in turn calls the function we passed to our child component.
You'll have to tailor your use case to match the exam

I found a solution using Vuex.
So now my components look like this.
Here is parent:
<template lang="pug">
.form
Input(v-for="data in formClient" v-bind:key="data.id" v-bind:data="data")
button(#click="pdfgen") Download PDF
</template>
<script>
export default {
components: {
Input: () => import('#/components/items/form/input'),
store: () => import('#/store'),
},
computed: {
formClient() { return this.$store.getters.client }
}
}
</script>
Here is a children (Input component):
<template lang="pug">
label.form_item
span.form_item_title {{ data.title }}
input.form_item_input(v-model="data.value" :type="data.input_type")
</template>
<script>
export default {
props: ['data'],
computed: {
form: {
get () {
return this.$store.state.obj.message
},
set (value) {
this.$store.commit('updateMessage', value)
}
}
}
}
</script>
Here is a store module:
<script>
export default {
actions: {},
mutations: {},
state: {
form: {
client: [
{id:'client_name', title:'Name', value: ''},
{id:'client_email', title: 'Email', value: ''},
{id:'foo', title: 'foo', value: ''}
]
}
},
getters: {
client: state => {
return state.form.client;
}
}
}
</script>
Now I can read updated data from store directly from PDFMake function.

Updating VueJS component data attributes when prop updates

I'm building a VueJS component which needs to update the data attributes when a prop is updated however, it's not working as I am expecting.
Basically, the flow is that someone searches for a contact via an autocomplete component I have, and if there's a match an event is emitted to the parent component.
That contact will belong to an organisation and I pass the data down to the organisation component which updates the data attributes. However it's not updating them.
The prop being passed to the organisation component is updated (via the event) but the data attibute values is not showing this change.
This is an illustration of my component's structure...
Here is my code...
Parent component
<template>
<div>
<blink-contact
:contact="contact"
v-on:contactSelected="setContact">
</blink-contact>
<blink-organisation
:organisation="organisation"
v-on:organisationSelected="setOrganisation">
</blink-organisation>
</div>
</template>
<script>
import BlinkContact from './BlinkContact.vue'
import BlinkOrganisation from './BlinkOrganisation.vue'
export default {
components: {BlinkContact, BlinkOrganisation},
props: [
'contact_id', 'contact_name', 'contact_tel', 'contact_email',
'organisation_id', 'organisation_name'
],
data () {
return {
contact: {
id: this.contact_id,
name: this.contact_name,
tel: this.contact_tel,
email: this.contact_email
},
organisation: {
id: this.organisation_id,
name: this.organisation_name
}
}
},
methods: {
setContact (contact) {
this.contact = contact
this.setOrganisation(contact.organisation)
},
setOrganisation (organisation) {
this.organisation = organisation
}
}
}
</script>
Child component (blink-organisation)
<template>
<blink-org-search
field-name="organisation_id"
:values="values"
endpoint="/api/v1/blink/organisations"
:format="format"
:query="getQuery"
v-on:itemSelected="setItem">
</blink-org-search>
</template>
<script>
export default {
props: ['organisation'],
data() {
return {
values: {
id: this.organisation.id,
search: this.organisation.name
},
format: function (items) {
for (let item of items.results) {
item.display = item.name
item.resultsDisplay = item.name
}
return items.results
}
}
},
methods: {
setItem (item) {
this.$emit('organisationSelected', item)
}
}
}
</script>
How can I update the child component's data properties when the prop changes?
Thanks!

Use a watch.
watch: {
organisation(newValue){
this.values.id = newValue.id
this.values.search = newValue.name
}
}
In this case, however, it looks like you could just use a computed instead of a data property because all you are doing is passing values along to your search component.
computed:{
values(){
return {
id: this.organisation.id
search: this.organisation.name
}
}
}

Passing props dynamically to dynamic component in VueJS

I've a dynamic view:
<div id="myview">
<div :is="currentComponent"></div>
</div>
with an associated Vue instance:
new Vue ({
data: function () {
return {
currentComponent: 'myComponent',
}
},
}).$mount('#myview');
This allows me to change my component dynamically.
In my case, I have three different components: myComponent, myComponent1, and myComponent2. And I switch between them like this:
Vue.component('myComponent', {
template: "<button #click=\"$parent.currentComponent = 'myComponent1'\"></button>"
}
Now, I'd like to pass props to myComponent1.
How can I pass these props when I change the component type to myComponent1?

To pass props dynamically, you can add the v-bind directive to your dynamic component and pass an object containing your prop names and values:
So your dynamic component would look like this:
<component :is="currentComponent" v-bind="currentProperties"></component>
And in your Vue instance, currentProperties can change based on the current component:
data: function () {
return {
currentComponent: 'myComponent',
}
},
computed: {
currentProperties: function() {
if (this.currentComponent === 'myComponent') {
return { foo: 'bar' }
}
}
}
So now, when the currentComponent is myComponent, it will have a foo property equal to 'bar'. And when it isn't, no properties will be passed.

You can also do without computed property and inline the object.
<div v-bind="{ id: someProp, 'other-attr': otherProp }"></div>
Shown in the docs on V-Bind - https://v2.vuejs.org/v2/api/#v-bind

You could build it like...
comp: { component: 'ComponentName', props: { square: true, outlined: true, dense: true }, model: 'form.bar' }
<component :is="comp.component" v-bind="{...comp.props}" v-model="comp.model"/>

I have the same challenge, fixed by the following:
<component :is="currentComponent" v-bind="resetProps">
{{ title }}
</component>
and the script is
export default {
…
props:['title'],
data() {
return {
currentComponent: 'component-name',
}
},
computed: {
resetProps() {
return { ...this.$attrs };
},
}
<div
:color="'error'"
:onClick="handleOnclick"
:title="'Title'"
/>
I'm came from reactjs and I found this solve my issue

If you have imported you code through require
var patientDetailsEdit = require('../patient-profile/patient-profile-personal-details-edit')
and initalize the data instance as below
data: function () {
return {
currentView: patientDetailsEdit,
}
you can also reference the component through the name property if you r component has it assigned
currentProperties: function() {
if (this.currentView.name === 'Personal-Details-Edit') {
return { mode: 'create' }
}
}

When you use the <component> inside a v-for you can change the answer of thanksd as follow:
methods: {
getCurrentProperties(component) {
if (component === 'myComponent') {
return {foo: baz};
}
}
},
usage
<div v-for="object in object.items" :key="object._your_id">
<component :is="object.component" v-bind="getCurrentProperties(object.component)" />
</div>
Let me know if there is an easier way.