We Keep Coding

How to pass data to a component template

Currently I'm defining several component template(s) within a single vue component. I've defined some as strings, however it makes it somewhat incomprehensible if it gets more complex. So instead I'm making it return a separate component as a template. However I'm not sure how to pass data to the component.
This is a sample of the current approach for one of my component templates within my vue component. It's returning the template as a string and renders the html.
progessTemplate: function () {
return {
template: ('progessTemplate', {
template: `
<div id="myProgress" class="pbar">
<div id="myBar" :class="barColor" :style="{'width': width}">
<div id="label" class="barlabel" v-html=width ></div>
</div>
</div>`,
data: function () {
return { data: {} };
},
computed: {
width: function () {
if (this.data.SLA <= 20) {
this.data.SLA += 20;
}
return this.data.SLA + '%';
},
barColor: function(){
if(this.data.SLA > 60 && this.data.SLA <= 80){
return 'bar progressWarning';
}else if(this.data.SLA > 80){
return 'bar progressUrgent';
}
}
}
})
}
},
I'd like to avoid this approach and call a separate file instead.
I import the component into my vue file
import QueryDetailTemplate from '../../ej2/queryDetailTemplate';
and within my main vue file I have this function 'QueryDetailTemplate':
export default{
data(){
return{
data: [...],
QueryDetailTemplate: function(){
return {
template: QueryDetailTemplate,
props:{
test: 'Hello World',
},
};
},//end of QueryDetailTemplate
}//end of data
...
}
In my QueryDetailTemplate.vue this is my code:
<template>
<div>
Heyy {{test}} //undefined
</div>
</template>
<script>
export default{
props: ['test'],
created(){
console.log(this.test); //shows undefined
}
}
</script>
It renders the 'Heyy' that's hardcoded but it doesn't get the 'test' prop.
Appreciate any pointers

I'm not quite sure what you're trying to achieve but...you should be specifying the component as a component like so:
export default{
components: {
QueryDetailTemplate
},
data(){
return{
data: [...],
}
}
OR if you want to import it asynchronously:
import Vue from 'vue'
export default {
methods: {
import() {
Vue.component(componentName, () => import(`./${componentName}.vue`));
}
}
}
And then you can render it in main:
<query-detail-template
test='Hello World'>
</query-detail-template>

Sibling component communication not working in vue

I am trying to send this.TC from typing.js to ending-page.js which are sibling components. Emits and event hubs not working. But emit from typing.js to parent works as I want. (There will be only one more call in this app, so i don't want use Vuex if it isnt necessary for this - i want to do it with simple emits ) Here's my code:
Parent:
<template>
<div id = "app">
<typing v-if = "DynamicComponent === 'typing'" />
<ending_page v-else-if = "DynamicComponent === 'ending_page'" />
</div>
</template>
<script>
/* Importing siblings components to parent component */
import typing from './components/typing/index.vue'
import ending_page from './components/ending-page/index.vue'
export default {
name: 'app',
components: {
typing,
ending_page
},
data() {
return {
DynamicComponent: "typing",
};
},
methods: {
updateDynamicComponent: function(evt, data){
this.DynamicComponent = evt;
},
},
};
</script>
typing.js:
import { eventBus } from "../../main";
export default {
name: 'app',
components: {
},
data() {
return {
/* Text what is in input. If you write this.input = "sometext" input text will change (It just works from JS to HTML and from HTML to JS) */
input: "",
/* Object of TypingCore.js */
TC: "somedata",
/* Timer obejct */
timer: null,
is_started: false,
style_preferences: null,
};
},
ICallThisFunctionWhenIWantToEmitSomething: function(evt) {
/* Sending data to ending_page component */
this.$root.$emit('eventname', 'somedata');
/* Calling parent to ChangeDynamicComponent && sending TC.data what will be given to ending_page (I think it looks better with one syntax here) */
this.$emit('myEvent', 'ending_page', this.TC.data);
}
},
};
ending-page.js:
import { eventBus } from "../../main";
export default {
name: 'ending-page',
components: {},
data () {
return {
data: "nothing",
}
},
computed: {
},
props: {
},
methods: {
},
/* I know arrow functions etc but i was trying everyting */
created: function () {
this.$root.$on('eventname', function (data) {
console.log(data)
this.title = data
this.$nextTick()
})
}
}

It is an example of how to share data between siblings components.
Children components emits events to parent. Parent components send data to children.
So, the parent has the property title shared between the children. When typing emits
the input event the directive v-modelcapture it an set the value on parent.
Ref:
https://v2.vuejs.org/v2/guide/components-props.html#One-Way-Data-Flow
https://v2.vuejs.org/v2/guide/components.html#Using-v-model-on-Components
https://benjaminlistwon.com/blog/data-flow-in-vue-and-vuex/
Vue.component('typing', {
props: {
value: ''
},
template: '<button #click="emit">Click to change</button>',
methods: {
emit() {
this.$emit('input', `changed on ${Date.now()}`);
}
}
});
Vue.component('ending-page', {
props: {
title: ''
},
template: '<div>{{ title }}</div>',
});
var app = new Vue({
el: '#app',
data() {
return {
title: 'unchanged',
};
},
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
<typing v-model="title"></typing>
<ending-page :title="title"></ending-page>
</div>

One can try communication using vuex,
the data you want to share make it on this.$store.state or if recalling for functions use mutation(sync functions) and actions(async functions)
https://vuex.vuejs.org/

I like what Jeffrey Way suggested once, just create a global events object (which accidentally can be another Vue instance) and then use that as an event bus for any global communication.
window.eventBus = new Vue();
// in components that emit:
eventBus.$emit('event', data);
// in components that listen
eventBus.$on('event');

Vue component using computed property of the mixin

I have a simple component that uses mixin that's shared across multiple components with similar functionality.
When I run it I seem to be getting
Property or method "activeClass" is not defined on the instance but
referenced during render.
Here's my mixin
<script>
export default {
data() {
return {
opened: false,
identity: ''
}
},
computed: {
activeClass() {
return {
active: this.opened
};
}
},
created() {
window.EventHandler.listen(this.identity + '-toggled', opened => this.opened = opened);
},
methods: {
toggle() {
window.EventHandler.fire('toggle-' + this.identity);
}
}
}
</script>
and my component
<template>
<span class="pointer" :class="activeClass" #click="toggle"><i class="fas fa-search"></i></span>
</template>
<script>
import Trigger from '../../mixins/Trigger';
export default {
data() {
return {
mixins: [Trigger],
data() {
return {
identity: 'language'
}
}
}
}
}
</script>
For some reason I cannot seem to be able to access activeClass computed property from within the component. Any idea why is this happening?

Try to move mixin to components main scope. Not in data function rerurn

How to call function on child component on parent events

Context
In Vue 2.0 the documentation and others clearly indicate that communication from parent to child happens via props.
Question
How does a parent tell its child an event has happened via props?
Should I just watch a prop called event? That doesn't feel right, nor do alternatives ($emit/$on is for child to parent, and a hub model is for distant elements).
Example
I have a parent container and it needs to tell its child container that it's okay to engage certain actions on an API. I need to be able to trigger functions.

Vue 3 Composition API
Create a ref for the child component, assign it in the template, and use the <ref>.value to call the child component directly.
<script setup>
import {ref} from 'vue';
const childComponentRef = ref(null);
function click() {
// `childComponentRef.value` accesses the component instance
childComponentRef.value.doSomething(2.0);
}
</script>
<template>
<div>
<child-component ref="childComponentRef" />
<button #click="click">Click me</button>
</div>
</template>
Couple things to note-
If your child component is using <script setup>, you'll need to declare public methods (e.g. doSomething above) using defineExpose.
If you're using Typescript, details of how to type annotate this are here.
Vue 3 Options API / Vue 2
Give the child component a ref and use $refs to call a method on the child component directly.
html:
<div id="app">
<child-component ref="childComponent"></child-component>
<button #click="click">Click</button>
</div>
javascript:
var ChildComponent = {
template: '<div>{{value}}</div>',
data: function () {
return {
value: 0
};
},
methods: {
setValue: function(value) {
this.value = value;
}
}
}
new Vue({
el: '#app',
components: {
'child-component': ChildComponent
},
methods: {
click: function() {
this.$refs.childComponent.setValue(2.0);
}
}
})
For more info, see Vue 3 docs on component refs or Vue 2 documentation on refs.

What you are describing is a change of state in the parent. You pass that to the child via a prop. As you suggested, you would watch that prop. When the child takes action, it notifies the parent via an emit, and the parent might then change the state again.
var Child = {
template: '<div>{{counter}}</div>',
props: ['canI'],
data: function () {
return {
counter: 0
};
},
watch: {
canI: function () {
if (this.canI) {
++this.counter;
this.$emit('increment');
}
}
}
}
new Vue({
el: '#app',
components: {
'my-component': Child
},
data: {
childState: false
},
methods: {
permitChild: function () {
this.childState = true;
},
lockChild: function () {
this.childState = false;
}
}
})
<script src="//cdnjs.cloudflare.com/ajax/libs/vue/2.2.1/vue.js"></script>
<div id="app">
<my-component :can-I="childState" v-on:increment="lockChild"></my-component>
<button #click="permitChild">Go</button>
</div>
If you truly want to pass events to a child, you can do that by creating a bus (which is just a Vue instance) and passing it to the child as a prop.

You can use $emit and $on. Using #RoyJ code:
html:
<div id="app">
<my-component></my-component>
<button #click="click">Click</button>
</div>
javascript:
var Child = {
template: '<div>{{value}}</div>',
data: function () {
return {
value: 0
};
},
methods: {
setValue: function(value) {
this.value = value;
}
},
created: function() {
this.$parent.$on('update', this.setValue);
}
}
new Vue({
el: '#app',
components: {
'my-component': Child
},
methods: {
click: function() {
this.$emit('update', 7);
}
}
})
Running example: https://jsfiddle.net/rjurado/m2spy60r/1/

A simple decoupled way to call methods on child components is by emitting a handler from the child and then invoking it from parent.
var Child = {
template: '<div>{{value}}</div>',
data: function () {
return {
value: 0
};
},
methods: {
setValue(value) {
this.value = value;
}
},
created() {
this.$emit('handler', this.setValue);
}
}
new Vue({
el: '#app',
components: {
'my-component': Child
},
methods: {
setValueHandler(fn) {
this.setter = fn
},
click() {
this.setter(70)
}
}
})
<script src="https://cdn.jsdelivr.net/npm/vue#2.5.17/dist/vue.js"></script>
<div id="app">
<my-component #handler="setValueHandler"></my-component>
<button #click="click">Click</button>
</div>
The parent keeps track of the child handler functions and calls whenever necessary.

Did not like the event-bus approach using $on bindings in the child during create. Why? Subsequent create calls (I'm using vue-router) bind the message handler more than once--leading to multiple responses per message.
The orthodox solution of passing props down from parent to child and putting a property watcher in the child worked a little better. Only problem being that the child can only act on a value transition. Passing the same message multiple times needs some kind of bookkeeping to force a transition so the child can pick up the change.
I've found that if I wrap the message in an array, it will always trigger the child watcher--even if the value remains the same.
Parent:
{
data: function() {
msgChild: null,
},
methods: {
mMessageDoIt: function() {
this.msgChild = ['doIt'];
}
}
...
}
Child:
{
props: ['msgChild'],
watch: {
'msgChild': function(arMsg) {
console.log(arMsg[0]);
}
}
}
HTML:
<parent>
<child v-bind="{ 'msgChild': msgChild }"></child>
</parent>

The below example is self explainatory. where refs and events can be used to call function from and to parent and child.
// PARENT
<template>
<parent>
<child
#onChange="childCallBack"
ref="childRef"
:data="moduleData"
/>
<button #click="callChild">Call Method in child</button>
</parent>
</template>
<script>
export default {
methods: {
callChild() {
this.$refs.childRef.childMethod('Hi from parent');
},
childCallBack(message) {
console.log('message from child', message);
}
}
};
</script>
// CHILD
<template>
<child>
<button #click="callParent">Call Parent</button>
</child>
</template>
<script>
export default {
methods: {
callParent() {
this.$emit('onChange', 'hi from child');
},
childMethod(message) {
console.log('message from parent', message);
}
}
}
</script>

If you have time, use Vuex store for watching variables (aka state) or trigger (aka dispatch) an action directly.

Calling child component in parent
<component :is="my_component" ref="my_comp"></component>
<v-btn #click="$refs.my_comp.alertme"></v-btn>
in Child component
mycomp.vue
methods:{
alertme(){
alert("alert")
}
}

I think we should to have a consideration about the necessity of parent to use the child’s methods.In fact,parents needn’t to concern the method of child,but can treat the child component as a FSA(finite state machine).Parents component to control the state of child component.So the solution to watch the status change or just use the compute function is enough

you can use key to reload child component using key
<component :is="child1" :filter="filter" :key="componentKey"></component>
If you want to reload component with new filter, if button click filter the child component
reloadData() {
this.filter = ['filter1','filter2']
this.componentKey += 1;
},
and use the filter to trigger the function

You can simulate sending event to child by toggling a boolean prop in parent.
Parent code :
...
<child :event="event">
...
export default {
data() {
event: false
},
methods: {
simulateEmitEventToChild() {
this.event = !this.event;
},
handleExample() {
this.simulateEmitEventToChild();
}
}
}
Child code :
export default {
props: {
event: {
type: Boolean
}
},
watch: {
event: function(value) {
console.log("parent event");
}
}
}

Mount parent component in child

I have two files named Recursive.vue and Value.vue.
In the first instance Recursive is the parent. Mounting Recursive in Recursive goes great, same for mounting Value in Recursive and after that Value in Value.
But when I've mounted Value in Recursive and trying to mount Recursive in Value after that I get the following error:
[Vue warn]: Failed to mount component: template or render function not defined.
(found in component <recursive>)
How can I make my problem work?
This is what my files are looking like:
Recursive
<template>
<div class="recursive">
<h1 #click="toggle">{{comps}}</h1>
<div v-if="isEven">
Hello
<value :comps="comps"></value>
</div>
</div>
</template>
<script>
import Value from './Value.vue'
export default {
name: 'recursive',
components: {
Value
},
props: {
comps: Number
},
computed: {
isEven () {
return this.comps % 2 == 0;
}
},
methods: {
toggle () {
this.comps++;
}
}
}
</script>
Value
<template>
<div class="value">
<h1 #click="toggle">{{comps}}</h1>
<div v-if="isEven">
<recursive :comps="comps"></recursive>
</div>
</div>
</template>
<script>
import Recursive from './Recursive.vue'
export default {
name: 'value',
components: {
Recursive
},
props: {
comps: Number
},
computed: {
isEven () {
return this.comps % 2 == 0;
}
},
methods: {
toggle () {
this.comps++;
}
}
}
</script>
Mounter
<template>
<div class="mounter">
<h1>HI</h1>
<recursive :comps="comps"></recursive>
</div>
</template>
<script>
import Recursive from './Recursive'
export default {
name: 'mounter',
components: {
Recursive
},
data () {
return {
comps: 0
}
}
}
</script>

I had a similar problem before. The only way out was declaring the component as "global", because importing it in the component which actually required it never worked.
new Vue({
...
})
Vue.component('recursive', require('./Recursive'))
Then you can just use without importing:
// Mounted
<template>
<div class="mounter">
<h1>HI</h1>
<recursive :comps="comps"></recursive>
</div>
</template>
<script>
export default {
name: 'mounter',
data () {
return {
comps: 0
}
}
}
</script>