I have a fairly simple VueJS app, 3 components (Login, SelectSomething, DoStuff)
Login component is just a form for user and pass input while the second component needs to display some data obtained in the login progress.
How can I share data from one component to the others? So that when I route to second component I still have the data obtained in the Login one?
You can either use props or an event bus, where you'll be able to emit an event from a component and listen on another
vm.$on('test', function (msg) {
console.log(msg)
})
vm.$emit('test', 'hi')
// -> "hi"
In Vue.js components can communicate with each other using props or events. It all depends on the relation between your components.
Let's take this small example:
<template>
<h2>Parent Component</h2>
<child-component></child-component>
</template>
To send information from the parent to Child, you will need to use props:
<template>
<h2>Parent Component</h2>
<child-component :propsName="example"></child-component>
</template>
<script>
export default {
data(){
return{
example: 'Send this variable to the child'
}
}
}
</script>
To send information from the child to the parent, you will need to use events:
Child Component
<script>
...
this.$emit('example', this.variable);
</script>
Parent Component
<template>
<h2>Parent Component</h2>
<child-component #example="methodName"></child-component>
</template>
<script>
export default {
methods: {
methodName(variable){
...
}
}
}
</script>
Check the documentation of vue.js for more information about this subject. This is a very brief introduction.
Use this small plugin if you have a lot of nested components:
Vue.use(VueGlobalVariable, {
globals: {
user: new User('user1'),
obj:{},
config:Config,
....
},
});
Now you can use $user in any component without using props or other
Related
I'm working in Nuxt3 and I've got a slightly unusual setup trying to watch or retrieve data from child components in a complex form that is structured as a multi-step wizard. It's obviously Vue underneath and I'm using the composition API.
My setup is that I have a page the wizard component is on, and that component has a prop that is an array of steps in the wizard. Each of these steps is some string fields for titles and labels and then a component type for the content. This way I can reuse existing form blocks in different ways. The key thing to understand is that the array of steps can be any length and contain any type of component.
Ideally, I'd like each child component to be unaware of being in the wizard so it can be reused elsewhere in the app. For example, a form that is one of the steps should handle its own validation and make public its state in a way the wizard component can read or watch.
The image below explains my basic setup.
The page includes this tag:
<Wizard :steps="steps" :object="project" #submit="createProject"/>
The Wizard loops over the steps to create each component.
<div v-for="(step) in steps" :key="step.name">
<component v-if="step.status === 'current'" :is="step.content.component" />
</div>
The data to setup the component with the right props for the wizard itself and the child component props.
const steps = ref([
{
name: 'overview',
title: t('overview'),
subTitle: t('projectCreateOverviewDescription'),
status: 'current',
invalid: true,
content: {
component: Overview,
props: null,
model: {}
}
},
{
name: 'members',
title: t('members'),
subTitle: t('projectCreateMembersDescription'),
status: 'upcoming',
invalid: false,
content: {
component: ThumbnailList,
props: {
objects: users,
title: t('users'),
objectNameSingular: t('user'),
objectNamePlural: t('users'),
So far I've tried to dynamically create references in the wizard component to watch the state of the children but those refs are always null. This concept of a null ref seems to be the accepted answer elsewhere when binding to known child components, but with this dynamic setup, it doesn't seem to be the right route.
interface StepRefs {
[key: string]: any
}
let stepRefs: StepRefs = {}
props.steps.forEach(step => {
stepRefs[step.name] = ref(null)
watch(() => stepRefs[step.name].value, (newValue, oldValue) => {
console.log(newValue)
console.log(oldValue)
}, { deep: true })
})
Can anyone direct me to the right approach to take for this setup? I have a lot of these wizards in different places in the app so a component approach is really attractive, but if it comes to it I'll abandon the idea and move that layer of logic to the pages to avoid the dynamic aspect.
To handle changes in child components I'd recommend to use events. You can have the children emit an event on change or completion, and the wizard is listening to events from all children and handling them respectively.
On the wizard subscribe to the event handler of the step component, and process the data coming from each step on completion (or whatever stage you need).
This way you don't need any special data type for the steps, they can just be an array. Simply use a ref to keep track of the current step. You don't even need a v-for, if you just display one step at a time. For a wizard navigation you might still need a v-for, but it would be much simpler. Please see a rough example below.
<div>
<stepComponent step="currentStep" #step-complete="handleStepComplete"/>
<div>
<wizardNavigationItemComponent v-for="step in steps" :active="step.name === currentStep.name" />
</div>
</div>
<script setup lang="ts">
const steps = step[/*your step data here*/]
const currentStepIndex = ref(0)
const currentStep = ref(steps[currentStepIndex.value])
function handleStepComplete(data) {
/* handle the data and move to next step */
currentStepIndex.value = currentStepIndex.value + 1 % steps.length
}
</script>
In the component you just need to define the event and emit it when the data is ready, to pass along the data:
<script setup lang="ts">
const emit = defineEmits<{
(event: "stepComplete", data: <your data type>): void
}>()
/* call emit in the component when its done / filled */
emit("stepComplete", data)
</script>
I hope this helps and can provide a viable path forward for you!
I have set up a bare bones vue project to show the problem. The only thing I added was the axios package. The problem is when I try to set the property of child component after an asynchronous call I cant read that property in the component. If you look at the code you can see I console log several times to show when I can get the data and when I cant. Please help me figure out what im missing here.
Parent
<template>
<div id="app">
<HelloWorld :test_prop="testData" :test_prop2="testData2" :test_prop3="testData3" test_prop4="I work also"/>
<div>{{testData5}}</div>
</div>
</template>
<script>
import HelloWorld from './components/HelloWorld.vue'
import axios from 'axios';
export default {
name: 'app',
components: {
HelloWorld
},
data() {
return {
testData: '',
testData2: 'I work just fine',
testData3: '',
testData5: ''
}
},
created: function(){
var self = this;
this.testDate3 = 'I dont work';
axios.get('https://jsonplaceholder.typicode.com/posts/42').then(function(response){
//I need this one to work
self.testData = 'I dont work either';
self.testData5 = 'I work also';
});
}
}
</script>
Child
<template>
</template>
<script>
export default {
name: 'HelloWorld',
props: ['test_prop', 'test_prop2', 'test_prop3', 'test_prop4'],
data() {
return {
comp_data: this.test_prop,
comp_data2: this.test_prop2,
comp_data3: this.test_prop3,
comp_data4: this.test_prop4
}
},
created: function(){
console.log(this.test_prop);
console.log(this.test_prop2);
console.log(this.test_prop3);
console.log(this.test_prop4);
}
}
</script>
Your console.log inside created hook will show you the initial state of this variables in Parent component. That's because Parent's created hook and Child's created hook will run at the same time.
So, when you solve your promise, Child component was already created. To understand this behavior, put your props in your template using {{ this.test_prop }}.
To solve it, depending on what you want, you can either define some default value to your props (see) or render your child component with a v-if condition. That's it, hope it helps!
On Vue created hook only the initial values of properties passed from main component. Therefore later updates (like your example "after ajax call") in main component will not effect to child component data variables because of that already child created hook take place.
If you want to update data later one way you can do like this:
watch: {
test_prop: function(newOne){
this.comp_data = newOne;
}
}
Adding watcher to property changes will update the last value of property from main component.
And also edit the typo this.testDate3. I guess it must be this.testData3
I'm trying to create a reusable styled input field in Vue. To make it styled (e.g. with an icon inside) I need to wrap it in another html-element.
Lets call the example below StyledInput
<div class="hasIcon">
<input />
<i class="someIcon"></i>
<div>
If I want to use StyledInput it might look like so:
<styled-input #keyup.enter="doSomething">
</styled-input>
But this would not work, due to the event listener being attached to the <div> instead of the <input>.
A workaround to that could be to emit all key-events from the input field:
<div class="hasIcon">
<input #keyup="$emit('keyup', $event) />
<i class="someIcon"></i>
<div>
But this will not scale well since it would have to be rewritten every time a developer uses an unmapped prop or event.
Is there a way to only make the inner element exposed to whomever uses it?
I'm not sure there is a Vue way to achieve this, because, as far as I'm aware there is no way to bind vue events dynamically, it is however possible to do this using vanilla javascript by passing all events as a prop then mapping them using addEventListener() to add your custom events:
Vue.component('my-input', {
template: "#my-input",
props: ['events'],
mounted() {
// get the input element
let input = document.getElementById('styled-input');
// map events
this.events.forEach((event) => {
let key = Object.keys(event);
input.addEventListener(key, event[key]);
});
}
})
Then you can just pass through all events as a prop like so:
<my-input :events="events"></my-input>
View Model:
var app = new Vue({
el: "#app",
data: {
events: [{
focus: () => {
console.log('focus')
}
}, {
keyup: (e) => {
console.log(e.which)
}
}]
}
})
Heres the JSFiddle: https://jsfiddle.net/h1dnk40v/
Of course, this means any developer would have to do things like map key codes etc, so you will lose some of the convenience Vue provides.
One thing I will just mention is that Vue components aren't necessarily intended to be infinitely reusable, they are supposed to provide specific functionality and encapsulate complex logic, so you would probably do better to implement the most likely use cases, and if the component doesn't fit you can extend it or write a new one for that particular event.
You can also use $attrs to pass props and events onto children elements:
<template>
<div>
<input v-bind="$attrs">
</div>
</template>
In Vue 3, you can specify a second script tag:
<script setup>
</script>
<script>
export default {
inheritAttrs: false,
};
</script>
https://vuejs.org/guide/components/attrs.html#disabling-attribute-inheritance
You could use slots to achieve this. If your <styled-input> template looks like this:
<div class="hasIcon">
<slot><input></slot>
<i class="someIcon"></i>
<div>
Then you can use it like this:
<styled-input>
<input #keyup.enter="doTheThing">
</styled-input>
Or, in cases where you don't care about the input events, like this:
<styled-input></styled-input>
and the default slot content (a bare <input>) will be used. You can use CSS to style the <input> inside the component, but you can't add custom properties or classes to it, so this approach may or may not fit your requirements.
I have a parent/child component setup where the parent is loading data from the server and passing it down to children via props. In the child I would like to instantiate a jQuery calendar with some of the data it receives from the parent.
In order to wait for the data before setting up the calendar, I broadcast an event in the parent that I have an event listener setup for in the child.
The listener is being fired in the child but if I this.$log('theProp'), it's undefined. However, if I inspect the components with the VueJs devtools, the parent/child relationship is there and the child has received the prop in the meantime.
The prop is defined on the child as a dynamic prop :the-prop="theProp". Since the child does receive the prop in the end, I'm assuming my setup is correct but there seems to be some sort of delay. The parent sets the props in the return function of the ajax call and again: it's working, just with a slight delay it seems.
I also tried registering a watch listener on the prop in the child so I could setup the calendar then and be sure that the prop is there. However, the watch listener fires, but this.$log('theProp') is still undefined.
If I pass the data along with the the broadcast call, like this.$broadcast('dataLoaded', theData) the child receives it just fine. But it seems wrong to do it that way as I'm basically building my own prop handler.
I'm not posting any code because the components are rather large and the VueJs devtools are telling me the parent/child situation is working.
Am I missing some information? Is there a slight delay between setting a value in the parent and the child receiving it? What would be the proper way to wait for parent data in the child?
Normally, when you're just rendering the data out into the template, the timing doesn't matter so much since the data is bound to the template. But in this case, I really need the data to be there to setup the calendar or it will be wrong.
Thanks.
edit 1: here's a jsfiddle: https://jsfiddle.net/dr3djo0u/1/
It seems to confirm that the data is not available immediately after the broadcast. However, the watcher does work, though I could almost swear that sometimes this.$log('someData') returned undefined when I setup that testcase.
But I guess my problem might be somewhere else, I'll have a look tonight, don't have the project with me right now.
edit 2: did some more tests. My problem was that a) event listeners do not seem to receive the data instantly and b) I was also trying to init the calendar in the route.data callback if someData was already around (e.g. when coming from parent), but that route callback is called before the component is ready, so it wasn't working there either.
My solution is now this:
// works when the child route is loaded directly and parent finishes loading someData
watch: {
someData() {
this.initCalendar();
}
},
// works when navigating from parent (data already loaded)
ready() {
if (this.someData && this.someData.length) {
this.initCalendar()
}
}
As far as I know, you should not need events to pass data from parent to child.
All you need is, in the child component: props: ['theProp']
And when using the child component in the parent: <child :theProp="someData"></child>
Now, wherever in the parent you change someData, the child component will react accordingly.
You don't need events, you don't need "watch", you don't need "ready".
For example: after an AJAX call, in the parent's "ready", you load some data:
// at the parent component
data: function () {
return {
someData: {}
}
},
ready: function () {
var vm = this;
$.get(url, function(response) {
vm.someData = response;
});
}
Now, you do not need anything else to pass the data to the child. It is already in the child as theProp!
What you really need to do is to have, in the child, something which reacts to data changes on its own theProp property.
Either in the interface:
<div v-if="theProp.id > 0">
Loaded!
</div>
Or in JavaScript code:
// at the child component
computed: {
// using a computed property based on theProp's value
awesomeDate: function() {
if (!this.theProp || (this.theProp.length === 0)) {
return false;
}
if (!this.initialized) {
this.initCalendar();
}
return this.theProp.someThing;
}
}
Update 1
You can also, in the parent, render the child conditionally:
<child v-if="dataLoaded" :theProp="someData"></child>
Only set dataLoaded to true when the data is available.
Update 2
Or maybe your issue is related to a change detection caveat
Maybe you're creating a new property in an object...
vm.someObject.someProperty = someValue
...when you should do...
vm.$set('someObject.someProperty', someValue)
...among other "caveats".
Update 3
In VueJS 2 you are not restricted to templates. You can use a render function and code the most complex rendering logic you want.
Update 4 (regarding OP's edit 2)
Maybe you can drop ready and use immediate option, so your initialization is in a single place:
watch: {
someData: {
handler: function (someData) {
// check someData and eventually call
this.initCalendar();
},
immediate: true
}
}
It's because tricky behavior in Vue Parent and Child lifecycle hooks.
Usually parent component fire created() hook and then mount() hook, but when there are child components it's not exactly that way: Parent fires created() and then his childs fire created(), then mount() and only after child's mount() hooks are loaded, parent loads his mount() as explained here. And that's why the prop in child component isn't loaded.
Use mounted() hook instead created()
like that https://jsfiddle.net/stanimirsp5/xnwcvL59/1/
Vue 3
Ok so I've spent like 1.5h trying to find out how to pass prop from parent to child:
Child
<!-- Template -->
<template>
<input type="hidden" name="_csrf_token" :value="csrfToken">
<span>
{{ csrfToken }}
</span>
</template>
<!-- Script -->
<script>
export default {
props: [
"csrfToken"
]
}
</script>
Parent
<!-- Template -->
<template>
<form #submit.prevent="submitTestMailForm" v-bind:action="formActionUrl" ref="form" method="POST">
...
<CsrfTokenInputComponent :csrf-token="csrfToken"/>
...
</form>
</template>
<!-- Script -->
<script>
...
export default {
data(){
return {
...
csrfToken : "",
}
},
methods: {
/**
* #description will handle submission of the form
*/
submitTestMailForm(){
let csrfRequestPromise = this.getCsrfToken();
let ajaxFormData = {
receiver : this.emailInput,
messageTitle : this.titleInput,
messageBody : this.bodyTextArea,
_csrf_token : this.csrfToken,
};
csrfRequestPromise.then( (response) => {
let csrfTokenResponseDto = CsrfTokenResponseDto.fromAxiosResponse(response);
this.csrfToken = csrfTokenResponseDto.csrToken;
this.axios({
method : "POST",
url : SymfonyRoutes.SEND_TEST_MAIL,
data : ajaxFormData,
}).then( (response) => {
// handle with some popover
})
});
},
/**
* #description will return the csrf token which is required upon submitting the form (Internal Symfony Validation Logic)
*/
getCsrfToken(){
...
return promise;
}
},
components: {
CsrfTokenInputComponent
}
}
</script>
Long story short
This is how You need to pass down the prop to child
<CsrfTokenInputComponent :csrf-token="csrfToken"/>
NOT like this
<CsrfTokenInputComponent csrf-token="csrfToken"/>
Even if my IDE keep me telling me yeap i can navigate with that prop to child - vue could not bind it.
solution (testing ok)
In child component just using the props data, no need to re-assignment props's values to data, it will be cause update bug!
vue child component props update bug & solution
https://forum.vuejs.org/t/child-component-is-not-updated-when-parent-component-model-changes/18283?u=xgqfrms
The problem is not how to pass data with props, but rather how to do two things at almost the same time.
I have an user account component that can edit users (with an user id) and add users (without id).
A child component shows checkboxes for user<->company assignments, and needs the user id to prepare API calls when the user account is saved.
It is important that the child component shows before saving the user account, so that things can be selected before the user is saved and gets an id.
So it has no user id at first: the id is passed to the child component as 'null'.
It updates when the user is stored and gets an id.
But at this point, it takes a very short time for the child to get the new id into its model.
If you call a function in the child component that relies on data that was just changing, it might happen that the function executes before the data is updated.
For cases like this, nextTick() is your friend.
import { nextTick } from 'vue';
...
saveAccount() {
axios.post(URL, this.userModel).then((result)) {
// our model gets an id when persisted
this.userModel.id=result.data.id;
nextTick( () => {
this.$refs.childComponent.doSomething();
});
}
}
I faced a problem, I solve it by cookies but I want to solve the problem without cookies. I have a component which called app-header and It has another component which called outmodal.
Now, My first Vue instance require component app-header.
var vue = new Vue({
el : "html",
data : {
title : "Site Title",
description : "description of page",
keywords : "my keywords",
view : "home",
login : "login"
},
components:{
"app-header" :require("../../components/header"),
"app-footer" :require("../../components/footer"),
"home" :require("../../views/home")
},
});
code of app-header
var Vue = require("vue");
Vue.partial("login",require("../../partials/login.html"));
Vue.partial("logged",require("../../partials/logged.html"));
module.exports = {
template : require("./template.html"),
replace : true,
components : {
outmodal : require("../outmodal")
},
props : ['login']
}
code of outmodal
var Vue = require("vue");
Vue.partial("loginModal",require("../../partials/loginModal.html"));
module.exports = {
template : require("./template.html"),
replace : true,
props : ['name'],
data : function () {
return {
userLogin : { mail : "", password : "", remember : ""}
}
},
methods : {
formSubmit : function(e){
e.preventDefault();
this.$http.post("http://example.com/auth/login",{ "email": this.userLogin.mail , "password": this.userLogin.password },function(data,status,request){
$.cookie("site_token",data.token,{expires : 1})
}).error(function(data,status,request){
});
}
}, ready : function(){
console.log("it works")
}
}
In outmodal component I connect the API and I check the login, If login will be succesfull, I want to change value of login variable in my Vue instance. I use web pack to build all requires. So I don't know how can I data binding between these files.
How can I solve It? I
The Best Solution which I found
For 0.12
http://012.vuejs.org/guide/components.html#Inheriting_Parent_Scope
for 1.0
http://v1.vuejs.org/guide/components.html#Parent-Child-Communication
for 2.0
https://v2.vuejs.org/v2/guide/components.html#Composing-Components (use props to one-way bind data from parent to child)
There are several ways of doing it, and some are mentioned in other answers:
Use props on components
Use v-model attribute
Use the sync modifier (for Vue 2.0)
Use v-model arguments (for Vue 3.0)
Use Pinia
Here are some details to the methods that are available:
1.) Use props on components
Props should ideally only be used to pass data down into a component and events should pass data back up. This is the way the system was intended. (Use either v-model or sync modifier as "shorthands")
Props and events are easy to use and are the ideal way to solve most common problems.
Using props for two-way binding is not usually advised but possible, by passing an object or array you can change a property of that object and it will be observed in both child and parent without Vue printing a warning in the console.
Because of how Vue observes changes all properties need to be available on an object or they will not be reactive.
If any properties are added after Vue has finished making them observable 'set' will have to be used.
//Normal usage
Vue.set(aVariable, 'aNewProp', 42);
//This is how to use it in Nuxt
this.$set(this.historyEntry, 'date', new Date());
The object will be reactive for both component and the parent:
I you pass an object/array as a prop, it's two-way syncing automatically - change data in the
child, it is changed in the parent.
If you pass simple values (strings, numbers)
via props, you have to explicitly use the .sync modifier
As quoted from --> https://stackoverflow.com/a/35723888/1087372
2.) Use v-model attribute
The v-model attribute is syntactic sugar that enables easy two-way binding between parent and child. It does the same thing as the sync modifier does only it uses a specific prop and a specific event for the binding
This:
<input v-model="searchText">
is the same as this:
<input
v-bind:value="searchText"
v-on:input="searchText = $event.target.value"
>
Where the prop must be value and the event must be input
3.) Use the sync modifier (for Vue 2.0)
The sync modifier is also syntactic sugar and does the same as v-model, just that the prop and event names are set by whatever is being used.
In the parent it can be used as follows:
<text-document v-bind:title.sync="doc.title"></text-document>
From the child an event can be emitted to notify the parent of any changes:
this.$emit('update:title', newTitle)
4.) Use v-model arguments (for Vue 3.0)
In Vue 3.x the sync modifier was removed.
Instead you can use v-model arguments which solve the same problem
<ChildComponent v-model:title="pageTitle" />
<!-- would be shorthand for: -->
<ChildComponent :title="pageTitle" #update:title="pageTitle = $event" />
5.) Use Pinia (or Vuex)
As of now Pinia is the official recommended state manager/data store
Pinia is a store library for Vue, it allows you to share a state across components/pages.
By using the Pinia store it is easier to see the flow of data mutations and they are explicitly defined. By using the vue developer tools it is easy to debug and rollback changes that were made.
This approach needs a bit more boilerplate, but if used throughout a project it becomes a much cleaner way to define how changes are made and from where.
Take a look at their getting started section
**In case of legacy projects** :
If your project already uses Vuex, you can keep on using it.
Vuex 3 and 4 will still be maintained. However, it's unlikely to add new functionalities to it. Vuex and Pinia can be installed in the same project. If you're migrating existing Vuex app to Pinia, it might be a suitable option. However, if you're planning to start a new project, we highly recommend using Pinia instead.
i found this one to be more accurate.
https://v2.vuejs.org/v2/guide/components.html#sync-Modifier
only in 2.3.0+ tho.
and honestly it's still not good enough. should simply be a easy option for 'two-way' data binding. so none of these options is good.
try using vuex instead. they have more options for such purpose.
https://vuex.vuejs.org/en/state.html
I would prefer event-driven updates as recommended in the documentation. However, I was limited by the existing ("third-party") component already using props and $emit. This component is my grandchild. The following is my solution (passing value through child using props, sync and computed value with $emit.
Comments are welcome.
Value can be modified in parent and grandchild without error:
Grandchild (simplified third-party component):
<template>
<div v-show="value">{{ value}}</div>
<button #click="closeBox">Close</button>
</template>
<script>
export default {
props: {
value: null
},
methods: {
closeBox() {
this.$emit('update:value', null);
}
}
}
</script>
Child:
<template>
<grandchild-component :value.sync="passedValue" />
</template>
<script>
export default {
props: {
value: null
},
computed: {
passedValue: {
get() {
return this.value;
},
set(newVal) {
this.$emit('update:value', newVal);
}
}
}
}
</script>
Parent:
<template>
<child-component :value.sync="value" />
</template>
<script>
export default {
data() {
return {
value: null,
}
},
// ... e.g. method setting/modifying the value
}
</script>