I just started using Vue and I have a very simple issue that I just can't get to work! I'm trying to create a mounted event that runs a method with a specific parameter inside it to alter the "show" value of an element. here is the code:
export default {
data(){
return {
one: false,
}
},
methods: {
show: function(el) {
this.el = true;
}
},
mounted(){
this.show(this.one)
}
}
I want "el" to be just a generic placeholder for whatever "data" name is passed into the method. in the future I may not only have "one" but also "two", "three" and "four". I want the "show" method to be able to take in any reference to one of these 4 options and change its value from false to true.
in the show method, I get the error "'el' is defined but never used."
the only solution I've come to is to do an if method "if this.one === el{...}" but that kind of defeats the purpose. any help would be appreciated
You can do something like this:
export default {
data(){
return {
one: false,
two: false
}
},
methods: {
doSomething(el) {
this[el] = true;
}
},
mounted(){
//Also works with vue props!
this.doSomething('one')
this.doSomething('two')
}
}
But if the function is more complex you should build a componet for that. Thats the vue way.
new Vue({
el: '#editor',
data: {
el: false,
item : ''
},
computed: {
},
methods: {
show (passedValue, item) {
this.item = item
this.el = passedValue
}
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<script src="https://unpkg.com/marked#0.3.6"></script>
<script src="https://unpkg.com/lodash#4.16.0"></script>
<div id="editor">
<div id="div1" v-if="el===true && item =='div-1'" class="show">
div1 displayed
</div>
<div id="div-2" v-if="el===true && item =='div-2'" class="show">
div2 displayed
</div>
<button v-on:click="show(true, 'div-1')">show div1</button>
<button v-on:click="show(false, 'div-1')">hide div1</button>
<button v-on:click="show(true, 'div-2')">show div2</button>
<button v-on:click="show(false, 'div-2')">hide div2</button>
</div>
export default {
data(){
return {
one: false,
}
},
methods: {
show(bol) {
this.one = bol;
}
},
mounted(){
this.show(this.one)
}
}
Use above code it would work.
Related
I have this object:
this.object = {
one: { ... },
two: { ... },
three: { ... }
}
How can I remove, for example, the property three and make the UI rerender? I already tried to use delete but it seems that it does not change the state and the UI did not rerender.
When I use this.object = { }, it does rerender the UI. Last question, what type of object is this? Because it's hard to find an example or answer that uses this type of object.
From the Vue Reactivity Guide (which doesn't specifically tell you how to delete)
Vue cannot detect property addition or deletion
In order for these mutations to be reactive, you have to use Vue's built-in methods. You could do:
this.$delete(this.object, 'three');
OR
this.$set(this.object, 'three', undefined);
To answer your question about the object, it's an object literal.
Demo:
Vue.config.productionTip = false;
Vue.config.devtools = false
new Vue({
el: "#app",
data() {
return {
object: {
one: {},
two: {},
three: {}
}
}
},
methods: {
deleteProp() {
this.$delete(this.object, 'three');
//this.$set(this.object, 'three', undefined);
}
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="app">
{{ object }}
<button #click="deleteProp">Delete property</button>
</div>
Try this in the component
<template>
<ul>
<li v-for="(obj,key) in object" #click="deleteKey(key)">{{obj}}</li>
</ul>
</template>
export default {
name: "YourComponent",
data: () => {
return {
object: {
one: {},
two: {},
three: {}
}
}
},
methods: {
deleteKey: function (key) {
this.$delete(this.object, key);
}
},
components: {Loader}
}
On clicking the listed values, it will be removed and can see the UI changing.
Just do:
this.object.three = { } // just make it empty, or
delete this.object.three // or
delete this.object['three']
I am trying to show a span whenever v-if is equal to true in my child component. Could anyone advice what I did wrong. Currently, I have no idea what I did incorrectly.
Child Component
const cardsTemplate = {
template:
`
<fieldset v-if="show.seach_checkboxes">
<span>HELLO WORLD</span>
</fieldset>
`,
props: ['js_local'],
data() {
return {
show:{
search_checkboxes : {
type: Boolean,
default: true,
}
}
}
},
methods :{
change_boolean : function(reverse_boolean){
this.show[reverse_boolean] = !this.show[reverse_boolean]
console.log(this.show)
},
show_search_template: function(){
this.change_boolean('search_checkboxes')
},
get_search_template : function(){
$.post(this.js_local.ajaxurl,
{action : 'get_search_templates'}
).done((data)=>{
this.name = JSON.parse(data)
}).fail((error)=>{
console.log(error)
})
},
}
}
It looks like you're trying to use data() with type checking, the same way props is used. Try this:
data() {
return {
show: {
search_checkboxes: true
}
}
}
Also, in your template HTML, you've misspelled search_checkboxes, it's missing an "r".
<fieldset v-if="show.seach_checkboxes">
^^^
i'm trying to have a computed property in vuejs associated to a es6 class.
My Vue instance looks like this:
...
props: ['customClass'],
computed: {
localClass: {
get() {
return this.customClass
},
set (value) {
console.log("changed")
}
}
}
...
My class looks like this
class CustomClass {
constructor () {
this.selected = false
}
}
If i try to do something like that:
this.localClass.selected = true
but the setter is never called, like the reactivity has been lost and i don't understand why.
I also try:
Vue.set(this.localClass, 'selected', true)
I pass customClass as a prop, but even creating a new instance directly in the component it doesn't change the result.
In vuejs docs i don't recall a section talking about reactivity problem in es6 class, so i was wondering if someone know why and how to make my class reactive.
Thanks in advance
The setter of a computed property, say myComputedProperty, is triggered when you assign to that property (e.g. this.myComputedProperty = {something: 'else'}.
What you probably are looking for is a watcher, more specifically, a watcher with deep: true, such as:
watch: {
localClass: {
deep: true,
handler() {
out.innerHTML += "watched!";
}
}
},
Demo below.
class CustomClass {
constructor() {
this.selected = false
}
}
Vue.component('custom', {
template: '#custom',
props: ['customClass'],
computed: {
localClass: {
get() {
return this.customClass
},
set(value) {
out.innerHTML += "changed!\n";
}
}
},
watch: {
localClass: {
deep: true,
handler() {
out.innerHTML += "watched!\n";
}
}
},
methods: {
assignToSelected() {
this.localClass.selected = true
},
assignToLocalClass() {
this.localClass = {
selected: true
}
}
}
});
new Vue({
el: '#app',
data: {
test: new CustomClass()
},
})
#out { background: black; color: gray; }
span { font-size: x-small; font-family: verdana }
<script src="https://unpkg.com/vue"></script>
<template id="custom">
<div>
{{ localClass }}
<br>
<button #click="assignToSelected">assignToSelected</button>
<span>Note: will trigger "watched!" just once, because, since the value is hardcoded in the method (see code) subsequent clicks won't modify the value.</span>
<br><br>
<button #click="assignToLocalClass">assignToLocalClass</button>
<span>Note: assignToLocalClass() will trigger the computed setter, but wont trigger the watcher because the computed setter currently sets nothing, so nothing changed for the watcher to trigger.</span>
</div>
</template>
<div id="app">
<custom :custom-class="test"></custom>
</div>
<pre id="out"></pre>
someone to help me with this strange issue?
I have the following vue component:
<template lang="pug">
div
p.alert.alert-info {{value}}
button(#click="onChange") Change
</template>
<script>
import Vue from 'vue';
export default {
name: 'z-temp',
props: {
value: {
required: true
}
},
watch: {
value(val) {
console.log(val);
}
},
methods: {
onChange() {
this.$emit('input', Random.id());
}
}
};
</script>
I want to use v-model, but when I use <z-temp v-model="myDataField">, the myDataField changes with success when I click in the Change button, but when I make the inverse and put some value in myDataField, like myDataField: "foo" the custom component gets this.value as undefined instead as foo.
Can anyone help me please?
I am guessing that myDataField is not reactive so the problem is in the parent.
Can you clarify the problem, seems like it is working as it should, ie. the component does not seem to be the problem.
zTemp = Vue.component('ztemp', {
template: '#ztemp',
props: {
value: {
required: true
}
},
watch: {
value(val) {
console.log(val);
}
},
methods: {
onChange() {
this.$emit('input', Math.random());
}
}
});
new Vue({
el: '#app',
components: {
zTemp
},
data: {
myinput: '0.2'
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.4.4/vue.min.js"></script>
<div id="app">
{{myinput}}<br/>
<input v-model="myinput"/><br/>
<ztemp v-model="myinput"/><br/>
</div>
<script type="text/x-template" id="ztemp">
<div>
<p>{{value}}</p>
<button #click="onChange">Change</button>
</div>
</script>
thanks for helping, but I'm using meteor with vue-meteor, the problem was related to vue-meteor.
I changed the project structure to use separated Vue project in a .client folder and the problem gones. It was not a problema with component, but with vue-meteor package. Anyway, thank you guys.
I'm a bit confused about how to change properties inside components, let's say I have the following component:
{
props: {
visible: {
type: Boolean,
default: true
}
},
methods: {
hide() {
this.visible = false;
}
}
}
Although it works, it would give the following warning:
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: "visible"
(found in component )
Now I'm wondering what the best way to handle this is, obviously the visible property is passed in when created the component in the DOM: <Foo :visible="false"></Foo>
Referencing the code in your fiddle
Somehow, you should decide on one place for the state to live, not two. I don't know whether it's more appropriate to have it just in the Alert or just in it's parent for your use case, but you should pick one.
How to decide where state lives
Does the parent or any sibling component depend on the state?
Yes: Then it should be in the parent (or in some external state management)
No: Then it's easier to have it in the state of the component itself
Kinda both: See below
In some rare cases, you may want a combination. Perhaps you want to give both parent and child the ability to hide the child. Then you should have state in both parent and child (so you don't have to edit the child's props inside child).
For example, child can be visible if: visible && state_visible, where visible comes from props and reflects a value in the parent's state, and state_visible is from the child's state.
I'm not sure if this is the behavour that you want, but here is a snippet. I would kinda assume you actually want to just call the toggleAlert of the parent component when you click on the child.
var Alert = Vue.component('alert', {
template: `
<div class="alert" v-if="visible && state_visible">
Alert<br>
<span v-on:click="close">Close me</span>
</div>`,
props: {
visible: {
required: true,
type: Boolean,
default: false
}
},
data: function() {
return {
state_visible: true
};
},
methods: {
close() {
console.log('Clock this');
this.state_visible = false;
}
}
});
var demo = new Vue({
el: '#demo',
components: {
'alert': Alert
},
data: {
hasAlerts: false
},
methods: {
toggleAlert() {
this.hasAlerts = !this.hasAlerts
}
}
})
.alert {
background-color: #ff0000;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.5.17/vue.js"></script>
<div id="demo" v-cloak>
<alert :visible="hasAlerts"></alert>
<span v-on:click="toggleAlert">Toggle alerts</span>
</div>
According to the Vue.js component doc:
When the parent property updates, it will flow down to the child, but not the other way around. So, how do we communicate back to the parent when something happens? This is where Vue’s custom event system comes in.
Use $emit('my-event) from the child to send an event to the parent. Receive the event on the child declaration inside the parent with v-on:my-event (or #my-event).
Working example:
// child
Vue.component('child', {
template: '<div><p>Child</p> <button #click="hide">Hide</button></div>',
methods: {
hide () {
this.$emit('child-hide-event')
}
},
})
// parent
new Vue({
el: '#app',
data: {
childVisible: true
},
methods: {
childHide () {
this.childVisible = false
},
childShow () {
this.childVisible = true
}
}
})
.box {
border: solid 1px grey;
padding: 16px;
}
<script src="https://unpkg.com/vue/dist/vue.min.js"></script>
<div id="app" class="box">
<p>Parent | childVisible: {{ childVisible }}</p>
<button #click="childHide">Hide</button>
<button #click="childShow">Show</button>
<p> </p>
<child #child-hide-event="childHide" v-if="childVisible" class="box"></child>
</div>
If the prop is only useful for this child component, give the child a prop like initialVisible, and a data like mutableVisible, and in the created hook (which is called when the component's data structure is assembled), simply this.mutableVisible = this.initialVisible.
If the prop is shared by other children of the parent component, you'll need to make it the parent's data to make it available for all children. Then in the child, this.$emit('visibleChanged', currentVisible) to notify the parent to change visible. In parent's template, use <ThatChild ... :visibleChanged="setVisible" ...>. Take a look at the guide: https://v2.vuejs.org/v2/guide/components.html
After a read of your latest comments it seems that you are concerned about having the logic to show/hide the alerts on the parent. Therefore I would suggest the following:
parent
# template
<alert :alert-visible="alertVisible"></alert>
# script
data () {
alertVisible: false,
...
},
...
Then on the child alert you would $watch the value of the prop and move all logic into the alert:
child (alert)
# script
data: {
visible: false,
...
},
methods: {
hide () {
this.visible = false
},
show () {
this.visible = true
},
...
},
props: [
'alertVisible',
],
watch: {
alertVisible () {
if (this.alertVisible && !this.visible) this.show()
else if (!this.alertVisible && this.visible) this.hide()
},
...
},
...
To help anybody, I was facing the same issue. I just changed my var that was inside v-model="" from props array to data. Remember the difference between props and data, im my case that was not a problem changing it, you should weight your decision.
E.g.:
<v-dialog v-model="dialog" fullscreen hide-overlay transition="dialog-bottom-transition">
Before:
export default {
data: function () {
return {
any-vars: false
}
},
props: {
dialog: false,
notifications: false,
sound: false,
widgets: false
},
methods: {
open: function () {
var vm = this;
vm.dialog = true;
}
}
}
After:
export default {
data: function () {
return {
dialog: false
}
},
props: {
notifications: false,
sound: false,
widgets: false
},
methods: {
open: function () {
var vm = this;
vm.dialog = true;
}
}
}
Maybe it looks like on hack and violates the concept of a single data source, but its work)
This solution is creating local proxy variable and inherit data from props. Next work with proxy variable.
Vue.component("vote", {
data: function() {
return {
like_: this.like,
dislike_: this.dislike,
}
},
props: {
like: {
type: [String, Number],
default: 0
},
dislike: {
type: [String, Number],
default: 0
},
item: {
type: Object
}
},
template: '<div class="tm-voteing"><span class="tm-vote tm-vote-like" #click="onVote(item, \'like\')"><span class="fa tm-icon"></span><span class="tm-vote-count">{{like_}}</span></span><span class="tm-vote tm-vote-dislike" #click="onVote(item, \'dislike\')"><span class="fa tm-icon"></span><span class="tm-vote-count">{{dislike_}}</span></span></div>',
methods: {
onVote: function(data, action) {
var $this = this;
// instead of jquery ajax can be axios or vue-resource
$.ajax({
method: "POST",
url: "/api/vote/vote",
data: {id: data.id, action: action},
success: function(response) {
if(response.status === "insert") {
$this[action + "_"] = Number($this[action + "_"]) + 1;
} else {
$this[action + "_"] = Number($this[action + "_"]) - 1;
}
},
error: function(response) {
console.error(response);
}
});
}
}
});
use component and pass props
<vote :like="item.vote_like" :dislike="item.vote_dislike" :item="item"></vote>
I wonder why it is missed by others when the warning has a hint
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: "visible" (found in component )
Try creating a computed property out of the prop received in the child component as
computed: {
isVisible => this.visible
}
And use this computed in your child component as well as to emit the changes to your parent.