Vue reactive component props - vue.js

I have method in my component that adds popup and passing some props into its.
openPopup () {
this.$store.dispatch('addPopup', {
component: MapCropsPopup,
props: {
anchor: this.$refs.filter,
selectedCropIds: this.selectedCropIds,
activeSeason: this.activeSeason,
onBeforeClose: () => {
this.$router.push(this.getQuery({ showCrops: null }));
},
onSeasonChange: (season) => {
this.activeSeason = season;
}
}
});
}
Here, in child component i store all passed props into 'props' variable
props: ['props']
and use them directrly in template
<div class="mcp-seasons__btn"
:class="{ 'm--active': props.activeSeason === 'current' }"
#click="setActiveSeason('current')">
{{ i18n.CURRENT_LABEL }}</div>
To update current season in parent component I use method setActiveSeason
setActiveSeason (season) {
this.props.onSeasonChange(season);
}
it works good, and updates 'activeSeason' in parent component, but won't update same property in child component.
What should I do to make property reactive again?

When you do
selectedCropIds: this.selectedCropIds,
activeSeason: this.activeSeason,
you are making nonreactive members of an object that are initialized to the given values at the time. If, instead, you did something like
propParent: this
and in the popup component referred to props.propParent.activeSeason, you would be using the reactive item.

Related

Unexpected mutation of prop in Vue2 [duplicate]

I started https://laracasts.com/series/learning-vue-step-by-step series. I stopped on the lesson Vue, Laravel, and AJAX with this error:
vue.js:2574 [Vue warn]: Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders. Instead, use a data or computed property based on the prop's value. Prop being mutated: "list" (found in component )
I have this code in main.js
Vue.component('task', {
template: '#task-template',
props: ['list'],
created() {
this.list = JSON.parse(this.list);
}
});
new Vue({
el: '.container'
})
I know that the problem is in created() when I overwrite the list prop, but I am a newbie in Vue, so I totally don't know how to fix it. Does anyone know how (and please explain why) to fix it?
This has to do with the fact that mutating a prop locally is considered an anti-pattern in Vue 2
What you should do now, in case you want to mutate a prop locally, is to declare a field in your data that uses the props value as its initial value and then mutate the copy:
Vue.component('task', {
template: '#task-template',
props: ['list'],
data: function () {
return {
mutableList: JSON.parse(this.list);
}
}
});
You can read more about this on Vue.js official guide
Note 1: Please note that you should not use the same name for your prop and data, i.e.:
data: function () { return { list: JSON.parse(this.list) } } // WRONG!!
Note 2: Since I feel there is some confusion regarding props and reactivity, I suggest you to have a look on this thread
The Vue pattern is props down and events up. It sounds simple, but is easy to forget when writing a custom component.
As of Vue 2.2.0 you can use v-model (with computed properties). I have found this combination creates a simple, clean, and consistent interface between components:
Any props passed to your component remains reactive (i.e., it's not cloned nor does it require a watch function to update a local copy when changes are detected).
Changes are automatically emitted to the parent.
Can be used with multiple levels of components.
A computed property permits the setter and getter to be separately defined. This allows the Task component to be rewritten as follows:
Vue.component('Task', {
template: '#task-template',
props: ['list'],
model: {
prop: 'list',
event: 'listchange'
},
computed: {
listLocal: {
get: function() {
return this.list
},
set: function(value) {
this.$emit('listchange', value)
}
}
}
})
The model property defines which prop is associated with v-model, and which event will be emitted on changes. You can then call this component from the parent as follows:
<Task v-model="parentList"></Task>
The listLocal computed property provides a simple getter and setter interface within the component (think of it like being a private variable). Within #task-template you can render listLocal and it will remain reactive (i.e., if parentList changes it will update the Task component). You can also mutate listLocal by calling the setter (e.g., this.listLocal = newList) and it will emit the change to the parent.
What's great about this pattern is that you can pass listLocal to a child component of Task (using v-model), and changes from the child component will propagate to the top level component.
For example, say we have a separate EditTask component for doing some type of modification to the task data. By using the same v-model and computed properties pattern we can pass listLocal to the component (using v-model):
<script type="text/x-template" id="task-template">
<div>
<EditTask v-model="listLocal"></EditTask>
</div>
</script>
If EditTask emits a change it will appropriately call set() on listLocal and thereby propagate the event to the top level. Similarly, the EditTask component could also call other child components (such as form elements) using v-model.
Vue just warns you: you change the prop in the component, but when parent component re-renders, "list" will be overwritten and you lose all your changes. So it is dangerous to do so.
Use computed property instead like this:
Vue.component('task', {
template: '#task-template',
props: ['list'],
computed: {
listJson: function(){
return JSON.parse(this.list);
}
}
});
If you're using Lodash, you can clone the prop before returning it. This pattern is helpful if you modify that prop on both the parent and child.
Let's say we have prop list on component grid.
In Parent Component
<grid :list.sync="list"></grid>
In Child Component
props: ['list'],
methods:{
doSomethingOnClick(entry){
let modifiedList = _.clone(this.list)
modifiedList = _.uniq(modifiedList) // Removes duplicates
this.$emit('update:list', modifiedList)
}
}
Props down, events up. That's Vue's Pattern. The point is that if you try to mutate props passing from a parent. It won't work and it just gets overwritten repeatedly by the parent component. Child component can only emit an event to notify parent component to do sth. If you don't like these restrict, you can use VUEX(actually this pattern will suck in complex components structure, you should use VUEX!)
You should not change the props's value in child component.
If you really need to change it you can use .sync.
Just like this
<your-component :list.sync="list"></your-component>
Vue.component('task', {
template: '#task-template',
props: ['list'],
created() {
this.$emit('update:list', JSON.parse(this.list))
}
});
new Vue({
el: '.container'
})
According to the VueJs 2.0, you should not mutate a prop inside the component. They are only mutated by their parents. Therefore, you should define variables in data with different names and keep them updated by watching actual props.
In case the list prop is changed by a parent, you can parse it and assign it to mutableList. Here is a complete solution.
Vue.component('task', {
template: ´<ul>
<li v-for="item in mutableList">
{{item.name}}
</li>
</ul>´,
props: ['list'],
data: function () {
return {
mutableList = JSON.parse(this.list);
}
},
watch:{
list: function(){
this.mutableList = JSON.parse(this.list);
}
}
});
It uses mutableList to render your template, thus you keep your list prop safe in the component.
The answer is simple, you should break the direct prop mutation by assigning the value to some local component variables(could be data property, computed with getters, setters, or watchers).
Here's a simple solution using the watcher.
<template>
<input
v-model="input"
#input="updateInput"
#change="updateInput"
/>
</template>
<script>
export default {
props: {
value: {
type: String,
default: '',
},
},
data() {
return {
input: '',
};
},
watch: {
value: {
handler(after) {
this.input = after;
},
immediate: true,
},
},
methods: {
updateInput() {
this.$emit('input', this.input);
},
},
};
</script>
It's what I use to create any data input components and it works just fine. Any new data sent(v-model(ed)) from parent will be watched by the value watcher and is assigned to the input variable and once the input is received, we can catch that action and emit input to parent suggesting that data is input from the form element.
do not change the props directly in components.if you need change it set a new property like this:
data() {
return {
listClone: this.list
}
}
And change the value of listClone.
I faced this issue as well. The warning gone after i use $on and $emit.
It's something like use $on and $emit recommended to sent data from child component to parent component.
one-way Data Flow,
according to https://v2.vuejs.org/v2/guide/components.html, the component follow one-Way
Data Flow,
All props form a one-way-down binding between the child property and the parent one, when the parent property updates, it will flow down to the child but not the other way around, this prevents child components from accidentally mutating the parent's, which can make your app's data flow harder to understand.
In addition, every time the parent component is updates all props
in the child components will be refreshed with the latest value. This means you should not attempt to mutate a prop inside a child component. If you do .vue will warn you in the
console.
There are usually two cases where it’s tempting to mutate a prop:
The prop is used to pass in an initial value; the child component wants to use it as a local data property afterwards.
The prop is passed in as a raw value that needs to be transformed.
The proper answer to these use cases are:
Define a local data property that uses the prop’s initial value as its initial value:
props: ['initialCounter'],
data: function () {
return { counter: this.initialCounter }
}
Define a computed property that is computed from the prop’s value:
props: ['size'],
computed: {
normalizedSize: function () {
return this.size.trim().toLowerCase()
}
}
If you want to mutate props - use object.
<component :model="global.price"></component>
component:
props: ['model'],
methods: {
changeValue: function() {
this.model.value = "new value";
}
}
I want to give this answer which helps avoid using a lot of code, watchers and computed properties. In some cases this can be a good solution:
Props are designed to provide one-way communication.
When you have a modal show/hide button with a prop the best solution to me is to emit an event:
<button #click="$emit('close')">Close Modal</button>
Then add listener to modal element:
<modal :show="show" #close="show = false"></modal>
(In this case the prop show is probably unnecessary because you can use an easy v-if="show" directly on the base-modal)
You need to add computed method like this
component.vue
props: ['list'],
computed: {
listJson: function(){
return JSON.parse(this.list);
}
}
Vue.component('task', {
template: '#task-template',
props: ['list'],
computed: {
middleData() {
return this.list
}
},
watch: {
list(newVal, oldVal) {
console.log(newVal)
this.newList = newVal
}
},
data() {
return {
newList: {}
}
}
});
new Vue({
el: '.container'
})
Maybe this will meet your needs.
Vue3 has a really good solution. Spent hours to reach there. But it worked really good.
On parent template
<user-name
v-model:first-name="firstName"
v-model:last-name="lastName"
></user-name>
The child component
app.component('user-name', {
props: {
firstName: String,
lastName: String
},
template: `
<input
type="text"
:value="firstName"
#input="$emit('update:firstName',
$event.target.value)">
<input
type="text"
:value="lastName"
#input="$emit('update:lastName',
$event.target.value)">
`
})
This was the only solution which did two way binding. I like that first two answers were addressing in good way to use SYNC and Emitting update events, and compute property getter setter, but that was heck of a Job to do and I did not like to work so hard.
Vue.js props are not to be mutated as this is considered an Anti-Pattern in Vue.
The approach you will need to take is creating a data property on your component that references the original prop property of list
props: ['list'],
data: () {
return {
parsedList: JSON.parse(this.list)
}
}
Now your list structure that is passed to the component is referenced and mutated via the data property of your component :-)
If you wish to do more than just parse your list property then make use of the Vue component' computed property.
This allow you to make more in depth mutations to your props.
props: ['list'],
computed: {
filteredJSONList: () => {
let parsedList = JSON.parse(this.list)
let filteredList = parsedList.filter(listItem => listItem.active)
console.log(filteredList)
return filteredList
}
}
The example above parses your list prop and filters it down to only active list-tems, logs it out for schnitts and giggles and returns it.
note: both data & computed properties are referenced in the template the same e.g
<pre>{{parsedList}}</pre>
<pre>{{filteredJSONList}}</pre>
It can be easy to think that a computed property (being a method) needs to be called... it doesn't
For when TypeScript is your preferred lang. of development
<template>
<span class="someClassName">
{{feesInLocale}}
</span>
</template>
#Prop({default: 0}) fees: any;
// computed are declared with get before a function
get feesInLocale() {
return this.fees;
}
and not
<template>
<span class="someClassName">
{{feesInLocale}}
</span>
</template>
#Prop() fees: any = 0;
get feesInLocale() {
return this.fees;
}
Assign the props to new variable.
data () {
return {
listClone: this.list
}
}
Adding to the best answer,
Vue.component('task', {
template: '#task-template',
props: ['list'],
data: function () {
return {
mutableList: JSON.parse(this.list);
}
}
});
Setting props by an array is meant for dev/prototyping, in production make sure to set prop types(https://v2.vuejs.org/v2/guide/components-props.html) and set a default value in case the prop has not been populated by the parent, as so.
Vue.component('task', {
template: '#task-template',
props: {
list: {
type: String,
default() {
return '{}'
}
}
},
data: function () {
return {
mutableList: JSON.parse(this.list);
}
}
});
This way you atleast get an empty object in mutableList instead of a JSON.parse error if it is undefined.
YES!, mutating attributes in vue2 is an anti-pattern. BUT...
Just break the rules by using other rules, and go forward!
What you need is to add .sync modifier to your component attribute in the parent scope.
<your-awesome-components :custom-attribute-as-prob.sync="value" />
Below is a snack bar component, when I give the snackbar variable directly into v-model like this if will work but in the console, it will give an error as
Avoid mutating a prop directly since the value will be overwritten whenever the parent component re-renders. Instead, use a data or computed property based on the prop's value.
<template>
<v-snackbar v-model="snackbar">
{{ text }}
</v-snackbar>
</template>
<script>
export default {
name: "loader",
props: {
snackbar: {type: Boolean, required: true},
text: {type: String, required: false, default: ""},
},
}
</script>
Correct Way to get rid of this mutation error is use watcher
<template>
<v-snackbar v-model="snackbarData">
{{ text }}
</v-snackbar>
</template>
<script>
/* eslint-disable */
export default {
name: "loader",
data: () => ({
snackbarData:false,
}),
props: {
snackbar: {type: Boolean, required: true},
text: {type: String, required: false, default: ""},
},
watch: {
snackbar: function(newVal, oldVal) {
this.snackbarData=!this.snackbarDatanewVal;
}
}
}
</script>
So in the main component where you will load this snack bar you can just do this code
<loader :snackbar="snackbarFlag" :text="snackText"></loader>
This Worked for me
Vue.js considers this an anti-pattern. For example, declaring and setting some props like
this.propsVal = 'new Props Value'
So to solve this issue you have to take in a value from the props to the data or the computed property of a Vue instance, like this:
props: ['propsVal'],
data: function() {
return {
propVal: this.propsVal
};
},
methods: {
...
}
This will definitely work.
In addition to the above, for others having the following issue:
"If the props value is not required and thus not always returned, the passed data would return undefined (instead of empty)". Which could mess <select> default value, I solved it by checking if the value is set in beforeMount() (and set it if not) as follows:
JS:
export default {
name: 'user_register',
data: () => ({
oldDobMonthMutated: this.oldDobMonth,
}),
props: [
'oldDobMonth',
'dobMonths', //Used for the select loop
],
beforeMount() {
if (!this.oldDobMonth) {
this.oldDobMonthMutated = '';
} else {
this.oldDobMonthMutated = this.oldDobMonth
}
}
}
Html:
<select v-model="oldDobMonthMutated" id="dob_months" name="dob_month">
<option selected="selected" disabled="disabled" hidden="hidden" value="">
Select Month
</option>
<option v-for="dobMonth in dobMonths"
:key="dobMonth.dob_month_slug"
:value="dobMonth.dob_month_slug">
{{ dobMonth.dob_month_name }}
</option>
</select>
I personally always suggest if you are in need to mutate the props, first pass them to computed property and return from there, thereafter one can mutate the props easily, even at that you can track the prop mutation , if those are being mutated from another component too or we can you watch also .
Because Vue props is one way data flow, This prevents child components from accidentally mutating the parent’s state.
From the official Vue document, we will find 2 ways to solve this problems
if child component want use props as local data, it is best to define a local data property.
props: ['list'],
data: function() {
return {
localList: JSON.parse(this.list);
}
}
The prop is passed in as a raw value that needs to be transformed. In this case, it’s best to define a computed property using the prop’s value:
props: ['list'],
computed: {
localList: function() {
return JSON.parse(this.list);
},
//eg: if you want to filter this list
validList: function() {
return this.list.filter(product => product.isValid === true)
}
//...whatever to transform the list
}
You should always avoid mutating props in vue, or any other framework. The approach you could take is copy it into another variable.
for example.
// instead of replacing the value of this.list use a different variable
this.new_data_variable = JSON.parse(this.list)
A potential solution to this is using global variables.
import { Vue } from "nuxt-property-decorator";
export const globalStore = new Vue({
data: {
list: [],
},
}
export function setupGlobalsStore() {
Vue.prototype.$globals = globalStore;
}
Then you would use:
$globals.list
Anywhere you need to mutate it or present it.

Pass data from blade to vue and keep parent-child in sync?

I know that in Vue parents should update the children through props and children should update their parents through events.
Assume this is my parent component .vue file:
<template>
<div>
<my-child-component :category="category"></my-child-component>
</div>
</template>
<script>
export default {
data: {
return {
category: 'Test'
}
}
}
</script>
When I update the category data in this component, it will also update the category props in my-child-component.
Now, when I want to use Vue in Laravel, I usually use an inline template and pass the value from the blade directly to my components (as for example also suggested at https://stackoverflow.com/a/49299066/2311074).
So the above example my my-parent-component.blade.php could look like this:
#push('scripts')
<script src="/app.js"></script>
#endpush
<my-parent-component inline-template>
<my-child-component :category="{{ $category }}"></my-child-component>
</my-parent-component>
But now my-parent-component is not aware about the data of category. Basically only the child knows the category and there is no communication between parent and child about it.
How can I pass the data from blade without breaking the parent and child communication?
I just had to pass the category to the inline-template component through props like this:
#push('scripts')
<script src="/app.js"></script>
#endpush
<my-parent-component :initcategory="{$category}}" inline-template>
<my-child-component v-model="category"></my-child-component>
</my-parent-component>
In my-parent-component I had to set the props and initialize is using the create method:
export default {
props: {
initcategory: '',
},
data() {
return {
category: '',
};
},
created(){
this.category = this.initcategory;
}
}
Now my my-parent-component is fully aware of the category and it can communicate to the child using props and $emit as usual.
Your reference to this answer is different altogether from what you are looking for!
He's binding the :userId prop of the example component but not the parent component or in simple words: Any template using the example vue can either pass a string prop or bind :userId prop to a string variable. Following is similar:
<example :userId="{{ Auth::user()->id }}"></example>
OR
<example :userId="'some test string'"></example>
So you should rather assign {{ $category }} to a data variable but rather binds to a child component prop which will have no effect on the parent.
In the following snippet you're only binding the string but rather a data key:
<my-child-component :category="{{ $category }}"></my-child-component>
Update
See the following example which will change the h1 title after 3 seconds
// HelloWorld.vue
<template>
<app-name :name="appName" #appNameChanged="appName = $event"></app-name>
</template>
<script>
export default {
props: ['name'],
data() {
return {
appName: null
}
},
mounted() {
// NOTE: since Strings are immutable and thus will assign the value while objects and arrays are copied by reference
// the following is just for the purpose of understanding how binding works
this.appName = this.name;
}
}
</script>
The template which renders the app title or you can say the child component
// AppName.vue
<template>
<h1>{{ name }}</h1>
</template>
<script>
export default {
props: ['name'],
mounted() {
setTimeout(() => {
this.$emit('appNameChanged', 'Change App')
}, 3000);
}
}
</script>
And here's how it is being used in the welcome.blade.php
<div id="app">
<hello-world :name="'Laravel App'"></hello-world>
</div>

Vue how to get value from sub component

Here is my use case:
My main page have several sub-components that collect different input from user, finally I want to submit the whole page with all inputs collected. Therefore I want to retrieve the data from sub-component
One option is to use store, but my sub-components are super simple, just some forms, store seems too heavy...
Another option is that I can modify prop, although I know this is bad practice, but this approach looks just perfect....
Is it ok to modify prop if my logic is simple?(just collect inputs from user)Or I have to go for Vuex and store
Expanding on excellent answers from Ifaruki and Andres Foronda, another, related option is the use of the sync modifier on the child component's prop.
Suppose the child component has a prop named name. In the parent component, you can use the sync modifier like this:
<Child :name.sync="childName"></Child>
Then, in the child component, when the value of the name prop should be updated, don't update it directly. Instead, emit an event that follows the naming convention for sync-able props, which is update:nameOfProp. So in our example, the child component would do this:
this.$emit('update:name', newName);
The benefit of the sync modifier is that we don't have to write an event handler function in the parent component--Vue does that for us and updates the variable that is bound to the prop automatically.
You can read more details about the sync modifier in the official docs.
Retreiving data from sub component works with $emit here an exapmle:
//parent copmonent
<template>
<div>
<child #someEvent="someMethod"></child>
</div>
</template>
import child from "path/"
<script>
export default {
components: {
child
},
methods: {
someMethod(data){
console.log(data);
}
}
}
</script>
Child component
<template>
<div>
<button #click="sendEvent">send</button>
</div>
</template>
<script>
export default {
methods: {
sendEvent(){
this.$emit("someEvent", "working");
}
}
}
</script>
$emit takes 2 arguments. The first is the event name and the second one is the data that you send.
The parent just needs to listen with # for that event that being fired.
you can listen an event from child an update the parent data property
//parent component
<div>
<input-name #updateName="eventToUpdateName" /> <!--child component-->
</div>
...
data: () => ({ nameFromChild: '' )},
methods: {
eventToUpdateName(value) {
this.nameFromChild = value; // Update from child value emitted
}
}
...
And in the child component
// Child component
<input v-model="name" />
...
data: () => ({ name: '' }),
// watch for changes in the name property and emit an event, and pass the value to the parent
watch: { name() { this.$emit('updateName', this.name } }
...
Also, You can use a v-model directive and emit 'input' event from child.
//parent component
<div>
<input-name v-model="nameFromChild" /> <!--child component-->
</div>
...
data: () => ({ nameFromChild: '' )}
...
Now in the child component you can have
// Child component
<div>
<input v-model="name" />
</div>
data: () => ({ name: '' }),
props: { value: { type: String, default: '' },
created() { this.name = this.value }, // You can receive a default value
watch: { name() { this.$emit('input', this.name } }
...

Change value of a props in beforeDestroy/Destroyed cycle of child component does not work

Hi I made a boolean value in parent component, and passed it to the child component as a props. it has initialized as false, and after the user view the component, the value will change to true, which means the page has been visited.
I have done some research and followed How to properly pass data from child to parent and parent to child component?
here is my js code:
<script>
export default {
props: {
hasLoad: {
type: Boolean
}
},
data () {
return {
hasLoadModel: this.hasLoad
}
},
created: function() {
console.log(this.hasLoad);
},
beforeDestroy: function() {
this.hasLoadModel = true;
this.hasLoad = true;
console.log(this.hasLoadModel);
console.log(this.hasLoad);
}
}
</script>
and html code
<div v-model="skillLoadModel">..</div>
But I still get
[Vue warn]: Avoid mutating a prop directly since the value will be
overwritten whenever the parent component re-renders. Instead, use a
data or computed property based on the prop's value.
I have tried to change the value at either of beforeDestroy or Destroyed, or do not use v-model, but none of them works. The value has changed after I left the page, but when I reenter the page, the value has reset to default value.
Can someone help me please?
Thanks
Don't change the value of the prop. Have the component emit an event so that the parent can take the appropriate action.
Below is an example of a component that is created when the checkbox is checked, and is destroyed when it gets unchecked. The component emits a "dying" event, and the parent receives it and prints a scream to the console.
new Vue({
el: '#app',
data: {
showIt: true
},
methods: {
scream() {
console.log("Aaarg!");
}
},
components: {
myComponent: {
beforeDestroy: function() {
this.$emit('dying');
}
}
}
});
<script src="//unpkg.com/vue#latest/dist/vue.js"></script>
<div id="app">
<input type="checkbox" v-model="showIt">
<my-component v-if="showIt" hasload="true" #dying="scream" inline-template>
<div>Here I am</div>
</my-component>
</div>
I assume you're trying to communicate to the parent that the child has loaded. In that case, you can pass a function as a prop and simply call it when the child mounts.
Parent HTML:
<child :my-load-fn="loadFn"></child>
Parent JS:
methods: {
loadFn() {
this.childHasLoaded = true
}
}
Child JS:
props: ['myLoadFn'],
mounted() {
this.myLoadFn()
}

How to send updated values from Parent component to child component in Vue JS?

I am passing a variable from parent component to child component through props. But with some operation, the value of that variable is getting changed i.e. on click of some button in parent component but I did not know how to pass that updated value to child? suppose the value of one variable is false initially and there is Edit button in parent component. i am changing the value of this variable on click of Edit button and want to pass the updated value from parent to child component.
Your property's value should be updated dynamically when using props between parent and child components. Based on your example and the initial state of the property being false, it's possible that the value was not properly passed into the child component. Please confirm that your syntax is correct. You can check here for reference.
However, if you want to perform a set of actions anytime the property's value changes, then you can use a watcher.
EDIT:
Here's an example using both props and watchers:
HTML
<div id="app">
<child-component :title="name"></child-component>
</div>
JavaScript
Vue.component('child-component', {
props: ['title'],
watch: {
// This would be called anytime the value of title changes
title(newValue, oldValue) {
// you can do anything here with the new value or old/previous value
}
}
});
var app = new Vue({
el: '#app',
data: {
name: 'Bob'
},
created() {
// changing the value after a period of time would propagate to the child
setTimeout(() => { this.name = 'John' }, 2000);
},
watch: {
// You can also set up a watcher for name here if you like
name() { ... }
}
});
You can watch a (props) variable with the vue watch.
for example:
<script>
export default {
props: ['chatrooms', 'newmessage'],
watch : {
newmessage : function (value) {...}
},
created() {
...
}
}
</script>
I hope this will solve your problem. :)
Properties, where the value is an object, can be especially tricky. If you change an attribute in that object, the state is not changed. Thus, the child component doesn't get updated.
Check this example:
// ParentComponent.vue
<template>
<div>
<child-component :some-prop="anObject" />
<button type="button" #click="setObjectAttribute">Click me</button>
</div>
</template>
<script>
export default {
data() {
return {
anObject: {},
};
},
methods: {
setObjectAttribute() {
this.anObject.attribute = 'someValue';
},
},
};
</script>
// ChildComponent.vue
<template>
<div>
<strong>Attribute value is:</strong>
{{ someProp.attribute ? someProp.attribute : '(empty)' }}
</div>
</template>
<script>
export default {
props: [
'someProp',
],
};
</script>
When the user clicks on the "Click me" button, the local object is updated. However, since the object itself is the same -- only its attribute was changed -- a state change is not dispatched.
To fix that, the setObjectAttribute could be changed this way:
setObjectAttribute() {
// using ES6's spread operator
this.anObject = { ...this.anObject, attribute: 'someValue' };
// -- OR --
// using Object.assign
this.anObject = Object.assign({}, this.anObject, { attribute: 'someValue' });
}
By doing this, the anObject data attribute is receiving a new object reference. Then, the state is changed and the child component will receive that event.
You can use Dynamic Props.
This will pass data dynamically from the parent to the child component as you want.