I have the main component that containing other components which containing anothers components.
So, I have the click events in these components, but to handle it in my parent component, I need to make $emit call in each nested component.
How to make this process more simple, for example like in React, where I need just pass the function handler into component.
In vue 2.2.3+ you can use provide and inject to pass function from ancestor component to child, like great grandparent to child.
please refer following code
// app.vue
<template>
<div id="app">
<HelloWorld msg="button1" />
<HelloWorld msg="button2" />
<HelloWorld msg="button3" />
count: {{ count }}
</div>
</template>
<script>
import HelloWorld from "./components/HelloWorld";
export default {
name: "App",
provide() {
return {
clickHandler: this.clickHandler,
};
},
data() {
return {
count: 0,
};
},
components: {
HelloWorld,
},
methods: {
clickHandler() {
this.count += 1;
console.log("click received");
},
},
};
</script>
// HelloWorld.vue
<template>
<button #click="clickHandler">{{ msg }}</button>
</template>
<script>
export default {
name: "HelloWorld",
inject: ["clickHandler"],
props: {
msg: String,
},
};
</script>
you can see the same clickHandler function from parent is executed with modifying parents count prop on click of each children.
this clickHandler can be injected directly to any descendent at any level therefore application like
parent > child.1 > child.1.1 > child.1.1.1 > child.1.1.1.1(click)
the child.1.1.1.1 can be injected with clickHandler form parent.
try the code at codesandbox
also refer provide/inject
if you need the same value up in the hierarchy or anywhere in the current module, you should try to use the Vuex(State Management) library.
Related
Currently trying to use a method belonging to the parent
<p class="message-date text-center">
{{ $emit('format_date_day_month_year_time', message.date) }}
</p>
However I am getting the error.
Converting circular structure to JSON
--> starting at object with constructor 'Object'
How can I call a function inside a child component that does not rely on an event? I apologize for asking such a simple question but everything I was able to find on google is using $emit and using an event.
$emit was designed to only trigger an event on the current instance of vue. Therefore, it is not possible to receive data from another component this way.
For your case, I would suggest to use Mixins especially if you need to use certain functions among multiple vue components.
Alternately, let the child component call the the parent through $emit then receive the result from the parent through a prop.
Your code could be something as follows:
Child component
<template>
<p class="message-date text-center">
{{ date }}
</p>
</template>
<script>
export default {
name: 'Child',
props: {
date: String,
},
mounted() {
this.$emit("format-date", message.date);
},
}
</script>
Parent component
<template>
<Child :date="childDate" #format-date="formatChildDate" />
</template>
<script>
import Child from '#/components/Child';
export default {
components: {
Child,
},
data: () => ({
childDate: '',
}),
methods: {
formatChildDate(date) {
this.childDate = this.formatDateDayMonthYearTime(date)
},
formatDateDayMonthYearTime(date) {
//return the formatted date
},
},
}
</script>
with $emit you call a function where the Parent can listento.
where you are using it i would suggest a computed prop of the function.
But back to your Question here is a example of emiting and listen.
//Parent
<template>
<MyComponent #childFunction="doSomethingInParent($event)"/>
</template>
//Child
<template>
<button #click="emitStuff">
</template>
.....
methods:{
emitStuff(){
this.$emit(childFunction, somedata)
}
with the event you can give Data informations to a Parentcomponent.
how do you use a local component's data attriutes to bind an external component's v-model
for example i have this component
<publish-blog>
<VueTrix v-model="form.editorContent">
</publish-blog>
so the form.editorContent there refers to the publish-blog component's form.editorContent inside data, how do I do that ?
You can pass a prop to the publish-blog component.
This would be what ever page or component you are using the publish blog on, though to be honest I'm not sure why you would not just put the VueTrix component inside of the publish-blog component.
This would be on what ever page/component you are wanting it on.
<template>
<PublishBlog :trix="trix">
<VueTrix v-model="trix" />
</PublishBlog>
</template>
<script>
import PublishBlog from './PublishBlog.vue';
export default {
components: {
PublishBlog,
},
data() {
return {
trix: '',
};
},
};
</script>
and inside of the publish blog component make the form.editorContent the prop passed or a default value.
But without a global store/state you are stuck with props.
UPDATE: Showing what a publish blog component might look like
PublishBlog.vue
<template>
<section>
what ever goes here.
<slot />
</section>
</template>
<script>
export default {
name: 'PublishBlog',
props: {
trix: {
type: String,
default: '',
},
},
data() {
return {
form: {
editorContent: this.trix
},
};
},
};
</script>
I have been reading lots of articles about this, and it seems that there are multiple ways to do this with many authors advising against some implementations.
To make this simple I have created a really simple version of what I would like to achieve.
I have a parent Vue, parent.vue. It has a button:
<template>
<div>
<button v-on:click="XXXXX call method in child XXXX">Say Hello</button>
</div>
</template>
In the child Vue, child.vue I have a method with a function:
methods: {
sayHello() {
alert('hello');
}
}
I would like to call the sayHello() function when I click the button in the parent.
I am looking for the best practice way to do this. Suggestions I have seen include Event Bus, and Child Component Refs and props, etc.
What would be the simplest way to just execute the function in my method?
Apologies, this does seem extremely simple, but I have really tried to do some research.
Thanks!
One easy way is to do this:
<!-- parent.vue -->
<template>
<button #click="$refs.myChild.sayHello()">Click me</button>
<child-component ref="myChild" />
</template>
Simply create a ref for the child component, and you will be able to call the methods, and access all the data it has.
You can create a ref and access the methods, but this is not recommended. You shouldn't rely on the internal structure of a component. The reason for this is that you'll tightly couple your components and one of the main reasons to create components is to loosely couple them.
You should rely on the contract (interface in some frameworks/languages) to achieve this. The contract in Vue relies on the fact that parents communicate with children via props and children communicate with parents via events.
There are also at least 2 other methods to communicate when you want to communicate between components that aren't parent/child:
the event bus
vuex
I'll describe now how to use a prop:
Define it on your child component
props: ['testProp'],
methods: {
sayHello() {
alert('hello');
}
}
Define a trigger data on the parent component
data () {
return {
trigger: 0
}
}
Use the prop on the parent component
<template>
<div>
<childComponent :testProp="trigger"/>
</div>
</template>
Watch testProp in the child component and call sayHello
watch: {
testProp: function(newVal, oldVal) {
this.sayHello()
}
}
Update trigger from the parent component. Make sure that you always change the value of trigger, otherwise the watch won't fire. One way of doing this is to increment trigger, or toggle it from a truthy value to a falsy one (this.trigger = !this.trigger)
I don't like the look of using props as triggers, but using ref also seems as an anti-pattern and is generally not recommended.
Another approach might be: You can use events to expose an interface of methods to call on the child component this way you get the best of both worlds while keeping your code somehow clean. Just emit them at the mounting stage and use them when pleased. I stored it in the $options part in the below code, but you can do as pleased.
Child component
<template>
<div>
<p>I was called {{ count }} times.</p>
</div>
</template>
<script>
export default {
mounted() {
// Emits on mount
this.emitInterface();
},
data() {
return {
count: 0
}
},
methods: {
addCount() {
this.count++;
},
notCallable() {
this.count--;
},
/**
* Emitting an interface with callable methods from outside
*/
emitInterface() {
this.$emit("interface", {
addCount: () => this.addCount()
});
}
}
}
</script>
Parent component
<template>
<div>
<button v-on:click="addCount">Add count to child</button>
<child-component #interface="getChildInterface"></child-component>
</div>
</template>
<script>
export default {
// Add a default
childInterface: {
addCount: () => {}
},
methods: {
// Setting the interface when emitted from child
getChildInterface(childInterface) {
this.$options.childInterface = childInterface;
},
// Add count through the interface
addCount() {
this.$options.childInterface.addCount();
}
}
}
</script>
With vue 3 composition api you can do it like this:
Parent.vue
<script setup lang="ts">
const childRef = ref()
const callSayHello = () => {
childRef.value.sayHello()
}
</script>
<template>
<child ref="childRef"></child>
</template>
<style scoped></style>
Child.vue
<script setup lang="ts">
const sayHello = () => {
console.log('Hello')
}
defineExpose({ sayHello })
</script>
<template></template>
<style scoped></style>
I am not sure is this the best way. But I can explain what I can do...
Codesandbox Demo : https://codesandbox.io/s/q4xn40935w
From parent component, send a prop data lets say msg. Have a button at parent whenever click the button toggle msg true/false
<template>
<div class="parent">
Button from Parent :
<button #click="msg = !msg">Say Hello</button><br/>
<child :msg="msg"/>
</div>
</template>
<script>
import child from "#/components/child";
export default {
name: "parent",
components: { child },
data: () => ({
msg: false
})
};
</script>
In child component watch prop data msg. Whenever msg changes trigger a method.
<template>
<div class="child">I am Child Component</div>
</template>
<script>
export default {
name: "child",
props: ["msg"],
watch: {
msg() {
this.sayHello();
}
},
methods: {
sayHello() {
alert("hello");
}
}
};
</script>
This is an alternate take on Jonas M's excellent answer. Return the interface with a promise, no need for events. You will need a Deferred class.
IMO Vue is deficient in making calling child methods difficult. Refs aren't always a good option - in my case I need to call a method in one of a thousand grandchildren.
Parent
<child :getInterface="getInterface" />
...
export default {
setup(props) {
init();
}
async function init() {
...
state.getInterface = new Deferred();
state.childInterface = await state.getInterface.promise;
state.childInterface.doThing();
}
}
Child
export default {
props: {
getInterface: Deferred,
},
setup(props) {
watch(() => props.getInterface, () => {
if(!props.getInterface) return;
props.getInterface.resolve({
doThing: () => {},
doThing2: () => {},
});
});
}
}
I'm experiencing a problem where a custom event (swap-components) emitted from a dynamic component (A.vue or B.vue) is not being listened to correctly in the parent of the dynamic component (HelloWorld.vue).
Here is the source on GitHub (created using vue cli 3).
Here is a live demo showing the problem.
In the live demo, you'll see that clicking the button in the dynamic component with background color DOES NOT change the dynamic component. But when clicking the button below the background color (which originates in the HelloWorld.vue parent), the dynamic component DOES INDEED change.
Why is this happening and how to fix it?
Below I'll copy over the contents of the 3 main files of interest into this post:
HelloWorld.vue (the parent)
A.vue (sub component used in dynamic component)
B.vue (sub component used in dynamic component)
HelloWorld.vue:
<template>
<div>
<h1>The dynamic components ⤵️</h1>
<component
:is="current"
v-bind="dynamicProps"
></component>
<button
#click="click"
>Click me to swap components from within the parent of the dynamic component</button>
</div>
</template>
<script>
import A from "./A.vue";
import B from "./B.vue";
export default {
data() {
return {
current: "A"
};
},
computed: {
dynamicProps() {
return this.current === "A" ? { data: 11 } : { color: "black" };
}
},
methods: {
click() {
this.$emit("swap-components");
},
swapComponents() {
this.current = this.current === "A" ? "B" : "A";
}
},
mounted() {
this.$nextTick(() => {
// Code that will run only after the
// entire view has been rendered
this.$on("swap-components", this.swapComponents);
});
},
components: {
A,
B
},
props: {
msg: String
}
};
</script>
A.vue:
<template>
<section id="A">
<h1>Component A</h1>
<p>Data prop sent from parent: "{{ data }}"</p>
<button #click="click">Click me to swap components from within the dynamic component</button>
</section>
</template>
<script>
export default {
props: ["data"],
methods: {
click() {
this.$emit("swap-components");
}
}
};
</script>
B.vue:
<template>
<section id="B">
<h1>Component B</h1>
<p>Color prop sent from parent: "{{ color }}"</p>
<button #click="click">Click me to swap components from within the dynamic component</button>
</section>
</template>
<script>
export default {
props: ["color"],
methods: {
click() {
this.$emit("swap-components");
}
}
};
</script>
I'm guessing this is because the event listener is listening for a swap-components event emitted by the parent component itself. Perhaps you can fix that by listening for a swap-components event from the child component then emitting an event on the parent component.
<template>
<div>
<h1>The dynamic components ⤵️</h1>
<component
:is="current"
v-bind="dynamicProps"
#swap-components="$emit('swap-components')"
></component>
<button
#click="click"
>Click me to swap components from within the parent of the dynamic component</button>
</div>
</template>
Or you can call your method directly when the event is emitted by the child component ..
<template>
<div>
<h1>The dynamic components ⤵️</h1>
<component
:is="current"
v-bind="dynamicProps"
#swap-components="swapComponents"
></component>
<button
#click="click"
>Click me to swap components from within the parent of the dynamic component</button>
</div>
</template>
this is not bound to the context anymore when you use function. It is only limited to the function scope. Use arrow function to let this bound to the parent context.
Change:
this.$nextTick(function() {
With:
this.$nextTick(() => {
I'm using vue, version 2.5.8
I want to reload child component's, or reload parent and then force children components to reload.
I was trying to use this.$forceUpdate() but this is not working.
Do You have any idea how to do this?
Use a :key for the component and reset the key.
See https://michaelnthiessen.com/force-re-render/
Add key to child component, then update the key in parent. Child component will be re-created.
<childComponent :key="childKey"/>
If the children are dynamically created by a v-for or something, you could clear the array and re-assign it, and the children would all be re-created.
To simply have existing components respond to a signal, you want to pass an event bus as a prop, then emit an event to which they will respond. The normal direction of events is up, but it is sometimes appropriate to have them go down.
new Vue({
el: '#app',
data: {
bus: new Vue()
},
components: {
child: {
template: '#child-template',
props: ['bus'],
data() {
return {
value: 0
};
},
methods: {
increment() {
this.value += 1;
},
reset() {
this.value = 0;
}
},
created() {
this.bus.$on('reset', this.reset);
}
}
}
});
<script src="//cdnjs.cloudflare.com/ajax/libs/vue/2.4.2/vue.min.js"></script>
<div id="app">
<child :bus="bus">
</child>
<child :bus="bus">
</child>
<child :bus="bus">
</child>
<button #click="() => bus.$emit('reset')">Reset</button>
</div>
<template id="child-template">
<div>
{{value}} <button #click="increment">More!</button>
</div>
</template>
I'm using directive v-if which is responsible for conditional rendering. It only affects reloading HTML <template> part. Sections created(), computed are not reloaded. As I understand after framework load components reloading it is not possible. We can only re render a <template>.
Rerender example.
I have a Child.vue component code:
<template>
<div v-if="show">
Child content to render
{{ callDuringReRender() }}
</div>
</template>
<script>
export default {
data() {
return {
show: true
}
}
,
methods: {
showComponent() {
this.show = true
},
hideComponent() {
this.show = false
},
callDuringReRender() {
console.log("function recall during rendering")
}
}
}
</script>
In my Parent.vue component I can call child methods and using it's v-if to force the child rerender
<template>
<div>
<input type="button"
value="ReRender the child"
#click="reRenderChildComponent"/>
<child ref="childComponent"></child>
</div>
</template>
<script>
import Child from './Child.vue'
export default {
methods: {
reRenderChildComponent(){
this.$refs.childComponent.hideComponent();
this.$refs.childComponent.showComponent()
}
},
components: {
Child
}
}
</script>
After clicking a button in console You will notice message "function recall during rendering" informing You that component was rerendered.
This example is from the link that #sureshvv shared
import Vue from 'vue';
Vue.forceUpdate();
// Using the component instance
export default {
methods: {
methodThatForcesUpdate() {
// ...
this.$forceUpdate(); // Notice we have to use a $ here
// ...
}
}
}
I've found that when you want the child component to refresh you either need the passed property to be output in the template somewhere or be accessed by a computed property.
<!-- ParentComponent -->
<template>
<child-component :user="userFromParent"></child-component>
</template>
<!-- ChildComponent -->
<template>
<!-- 'updated' fires if property 'user' is used in the child template -->
<p>user: {{ user.name }}
</template>
<script>
export default {
props: {'user'},
data() { return {}; }
computed: {
// Or use a computed property if only accessing it in the script
getUser() {
return this.user;
}
}
}
</script>