I'm working currently with BootstrapVue.
I have a b-dropdown in my parent.vue where I can select a object of a JSON-File and convert it into an array because I need the length of this json object. This works fine!!
My problem is that I need to check in my parent.vue if something was selected - so if this.arrayLength is higher than 0 (until this point it works all well!). If this is true, it should use and show addElementsNotClickable() in my child.vue where no elements can be added (count of the inputs are equal to length of array) - otherwise it should use and show my button addElement() where multiple elements can be added manually.
But I'm not able to check in my child.vue if arrayLenght > 0... AND i don't know what to use on second button e.g #change(??) How can I solve that?
Many thanks! I've tried to be as detailed as I can!
Additional Info: I get no error codes!!
my parent.vue:
methods: {
inputedValue(input, index) {
var array = [];
const item= this.json.find((i) => i.Number === input);
for (let key in item.ID) {
array.push(item.ID[key]);
}
if(array.length > 0) {
this.getIndex = index;
this.getDataArray = array;
this.getLengthArray = array.length;
}
}
}
my child.vue (template)
<div class="mt-4 mb-5 ml-3 mr-3">
<b-button v-if="!hide" #click="addElement" variant="block">Add Element</b-button>
<b-button v-if="hide" #???="addElementNotClickable" variant="block">Not clickable ! </b-button>
</div>
my child.vue (script)
methods: {
addElementsNotClickable() {
for(let i = 1; i < this.arrayLength; i++) {
this.inputs.push({})
}
},
addElement() {
this.inputs.push({})
},
}
data() {
return {
inputs: [{}]
arrayLength: this.getLengthArray,
arrayIndex: this.getIndex,
hide: false,
}
props: [
"getLengthArray",
"getIndex"
],
You are misunderstanding how components should work in Vue. In short you can understand them by:
parent send props down and child send events up
What you are looking for is that whenever your arrayLength updates, you send an event to the parent. Then, it is the responsibility of the parent to handle that event. In this case, the parent would receive the event and store the length of the array.
Parent.vue
<template>
<div>
<child #arrayLenght:update="onArrayLenghtUpdate"/>
</div>
</template>
<script>
export default {
data: () => {
arrayLength: 0,
},
methods: {
onArrayLenghtUpdate(length) {
this.arrayLength = length;
}
}
}
</script>
Child.vue
<template> ... </template>
<script>
export default {
data: () => ({
arrayLength: 0,
}),
watch: {
arrayLenghth: function (newLenght) {
this.$emit('arrayLenght:update', newLenght);
}
}
}
</script>
This is the standard way and extremely useful if your Parent and Child aren't highly coupled together. If they are dependent on each other (you won't use Child.vue anywhere else in the app. Just as direct child of Parent.vue) then you can use the inject/provide approach. This approach is beyond the scope of this answer, feel free to read an article on it
Related
I'm trying to build what I'd assumed would be a relatively straightforward implementation of Ant-D's Tree component, and I'm running into issues.
Specifically, I'm unclear how to replicate the "half-checked" vs. "full-checked" behavior of their example. I'd like for the child nodes, when all fully checked, to also check their parent. Likewise when the parents are de-selected, I'd like all of the children to be deselected as well. Finally, when only some of a child nodes are checked/unchecked, the parent should go into a "half-checked" state.
The API seems to allow for this, and indeed they have an example here that purports to show off this functionality.
<template>
<a-tree
v-model:selectedKeys="selectedKeys"
v-model:checkedKeys="checkedKeys"
default-expand-all
checkable
:height="233"
:tree-data="treeData"
>
<template #title="{ title, key }">
<span v-if="key === '0-0-1-0'" style="color: #1890ff">{{ title }}</span>
<template v-else>{{ title }}</template>
</template>
</a-tree>
</template>
<script lang="ts">
import type { TreeProps } from 'ant-design-vue';
import { defineComponent, ref, watch } from 'vue';
function dig(path = '0', level = 3) {
const list: TreeProps['treeData'] = [];
for (let i = 0; i < 10; i += 1) {
const key = `${path}-${i}`;
const treeNode: TreeProps['treeData'][number] = {
title: key,
key,
};
if (level > 0) {
treeNode.children = dig(key, level - 1);
}
list.push(treeNode);
}
return list;
}
export default defineComponent({
setup() {
const selectedKeys = ref<string[]>(['0-0-0', '0-0-1']);
const checkedKeys = ref<string[]>(['0-0-0', '0-0-1']);
watch(selectedKeys, () => {
console.log('selectedKeys', selectedKeys);
});
watch(checkedKeys, () => {
console.log('checkedKeys', checkedKeys);
});
return {
treeData: dig(),
selectedKeys,
checkedKeys,
};
},
});
</script>
It's not clear to me how this works. Nowhere are they setting the checkedKeys data. Is this handled internally by the tree? I've tried copying this example locally and it's not even working.
The documentation further states about the checkedKeys prop:
"When this specifies the key of a treeNode which is also a parent treeNode, all the children treeNodes of will be checked; and vice versa, when it specifies the key of a treeNode which is a child treeNode, its parent treeNode will also be checked. When checkable and checkStrictly is true, its object has checked and halfChecked property."
If this example does not have checkStrictly set to true, then how are only some of the nodes supposed to become "half checked"?
I'm a beginner trying to get my app to pass props that set CSS styles down a chain to child components. I have a listener that checks for view port size, and as the window gets resized, it checks past a certain point and then swaps the css class and passes it down the chain..
I think I may be doing something incorrectly because my child components don't seem to be receiving the new styles and aren't updating in the DOM as I drag the window.
Here is my code.. I removed irrelevant code to make it easier to read:
Page_Listings.vue
<template>
<main>
<section>
<ListingRack
:prp_classes="rackClass"
/>
</section>
</main>
</template>
<script>
import ListingRack from './Listing__Rack.vue';
export default {
name: 'Front_Page__Panel',
data() {
return {
viewportWidth: window.innerWidth
}
},
methods: {},
mounted() { window.onresize = () => this.viewportWidth = window.innerWidth },
components: {ListingRack},
},
computed: {
rackClass: function(){
let theValue;
console.log('>> viewport width is now: ',this.viewportWidth)
if(this.viewportWidth > 1200) {
theValue = "grid_view";
console.log('>> grid view')
}
else {
theValue = 'card_view';
console.log('>> card view')
}
return theValue
}
}
}
</script>
Listing__Rack.vue
<template>
<div class="listing_rack" :class="classes">
<ul>
<li v-for="item in listings" :key="item.postId">
// I removed irrelevant code for hte sake of simplicity in this example.
// listings is a GraphQL returned array of data that generates a list of "listings".
<Listing
:prp_classes=classes
/>
</li>
</ul>
</div>
</template>
<script>
import Listing from './Listing.vue'
export default {
name: 'listing__rack',
data() {
return {
posts: [], // what we get from the database.
listings: [], // what we copy from the database.
classes: this.prp_classes
}
},
props: {
prp_classes: String
},
components: {
Listing
},
watch: {
classes: function(){
//just to check if we're receiving anything...
console.log(">> [Listing_Rack](watch)(classes) there was a change to classes!");
}
}
}
</script>
Listing.vue
<template>
<div :id=id
:class=classes
class="listing"
:style="backgroundStyle"
>
</div>
</template>
<script>
export default {
name: 'Listing',
data() {
return {
classes: this.prp_classes,
backgroundStyle: String
}
},
props: {
prp_classes: String
},
methods: {
checkClasses: function(){
if(this.classes === 'grid_view') this.backgroundStyle = 'background: center / cover no-repeat url(background.jpg);';
}
},
mounted: function() {
this.checkClasses();
},
watch: {
classes: function(){
this.checkClasses();
}
}
}
</script>
My console.logs on rackClass so I know the class swapping part is working, but all my subsequent child components don't seem to be updating accordingly..
Can someone tell me what I'm doing wrong? Is there a better way to do this? How come my props aren't being passed when I drag the window, and how can I dynamically set styles in the DOM?
Your code does not work because of the one big mistake (don't worry, many people do it)
You are passing your classes using props to child components. But instead of using this prop (prp_classes) directly in the child's template, you create an absolutely unnecessary classes property in the data()
Problem with that is that data() is executed only once when the component is created. If the value of the prp_classes prop changes later, classes property from the data() just holds the old value.
To fix this, remove unnecessary classes from the data and use the prop directly in the template...
...bit more explanation by example what is going on:
let prp_classes = 'card_view'
let classes = prp_classes
prp_classes = 'grid_view'
// prp_classes === 'grid_view', classes === 'card_view', prp_classes !== classes
// strings/numbers/Date ...all work the same
let o1 = { a: 1 }
let o2 = o1
o1.a = 2
// o1.a === 2, o2.a === 2, o1 === o2
More to study
I have a component with buttons that show some elements (v-autocomplete) when we click on them, but I should make it with a Boolean to simplify the code, how can I do that?
Because actually, it adds the index of the item in one array in showCompetence state, but I just would like a Boolean on each index Basically at the "openCompetence" function in "Methods".
import { mapGetters, mapActions } from "vuex";
export default {
name: "SkillCvCard",
data() {
return {
selectedCompetence: []
}
},
updated() {
this.addSelectSkill(this.userCompetences.competences.list);
console.log(this.selectedSkills)
},
props: {
userCompetences: {
type: Array
},
showCompetence: {
type: Array
}
},
computed: {
...mapGetters(["selectedSkills"]),
console: () => console,
},
methods: {
...mapActions(['addSelectSkill']),
openCompetence(index) {
if (this.showCompetence.includes(index)) {
console.log("close")
this.showCompetence.splice(this.showCompetence.indexOf(index), 1)
} else {
this.showCompetence.push(index)
console.log("open")
}
console.log(this.showCompetence)
}
}
about the template I will just add the minimum I hope it will be ok:
The first is where we click, to launch the "openCompetence" function.
<div v-for="(competences, index) of userCompetences.competences" :key="index">
{{ competences.category }} <v-btn #click="openCompetence(index)"> Add </v-btn>
</div>
the rest is a v-container with a v-for including multiple v-autocomplete, but the most important inside is the v-if:
<div class="skill-field" v-for="(skill, index) of userCompetences.competences" :key="index">
<template>
<v-flex md12 sm12 xs12 v-if="skill.list.length>0">
<v-autocomplete
v-if="showCompetence.includes(index)"
v-model="userCompetences.competences.list"
:items="skill.list"
chips
hide-selected
:label="skill.category"
item-text="name"
item-value="name"
multiple
>
</v-autocomplete>
</v-flex>
</template>
</div>
Normally, you would use a computed property to solve a problem like this. However, because you are inside of a v-for, a computed property is a little more difficult since you can't evaluate it in the context of each value of the v-for's index.
There are two common options:
Do exactly what you are doing. It's actually no less efficient since it will not re-evaluate unless data it depends on changes.
Add a computed called something like competencesDisplayState that returns an array of booleans that matches the ordering of the userCompetences.competences array in the v-for. Then your v-if can become something like:
v-if="competencesDisplayState[index]"
I normally just opt for the first approach as it is simpler and is easier to read and maintain.
If you want to go route 2, here's some code for the competencesDisplayState computed:
competencesDisplayState: () => {
var result = [];
for (var index=0;index < this.userCompetences.competences.length;++index) {
result(this.showCompetence.includes(index));
}
return result;
}
I am quite new with VueJS and I have been having trouble lately with some computed properties which do not update as I would like. I've done quite some research on Stack Overflow, Vue documentation and other ressources but i haven't found any solution yet.
The "app" is basic. I've got a parent component (Laundry) which has 3 child components (LaundryMachine). The idea is to have for each machine a button which displays its availability and updates the latter when clicked on.
In order to store the availability of all machines, I have a data in the parent component (availabilities) which is an array of booleans. Each element corresponds to a machine's availability.
When I click on the button, I know the array availibities updates correctly thanks to the console.log. However, for each machine, the computed property "available" does not update is I would want it to and I have no clue why.
Here is the code
Parent component:
<div id="machines">
<laundry-machine
name="AA"
v-bind:machineNum="0"
v-bind:availableArray="this.availabilities"
v-on:change-avlb="editAvailabilities"
></laundry-machine>
<laundry-machine
name="BB"
v-bind:machineNum="1"
v-bind:availableArray="this.availabilities"
v-on:change-avlb="editAvailabilities"
></laundry-machine>
<laundry-machine
name="CC"
v-bind:machineNum="2"
v-bind:availableArray="this.availabilities"
v-on:change-avlb="editAvailabilities"
></laundry-machine>
</div>
</div>
</template>
<script>
import LaundryMachine from './LaundryMachine.vue';
export default {
name: 'Laundry',
components: {
'laundry-machine': LaundryMachine
},
data: function() {
return {
availabilities: [true, true, true]
};
},
methods: {
editAvailabilities(index) {
this.availabilities[index] = !this.availabilities[index];
console.log(this.availabilities);
}
}
};
</script>
Child component:
<template>
<div class="about">
<h2>{{ name }}</h2>
<img src="../assets/washing_machine.png" /><br />
<v-btn color="primary" v-on:click="changeAvailability">
{{ this.availability }}</v-btn>
</div>
</template>
<script>
export default {
name: 'LaundryMachine',
props: {
name: String,
machineNum: Number,
availableArray: Array
},
methods: {
changeAvailability: function(event) {
this.$emit('change-avlb', this.machineNum);
console.log(this.availableArray);
console.log('available' + this.available);
}
},
computed: {
available: function() {
return this.availableArray[this.machineNum];
},
availability: function() {
if (this.available) {
return 'disponible';
} else {
return 'indisponible';
}
}
}
};
</script>
Anyway, thanks in advance !
Your problem comes not from the computed properties in the children, rather from the editAvailabilities method in the parent.
The problem is this line in particular:
this.availabilities[index] = !this.availabilities[index];
As you can read here, Vue has problems tracking changes when you modify an array by index.
Instead, you should do:
this.$set(this.availabilities, index, !this.availabilities[index]);
To switch the value at that index and let Vue track that change.
In Vue.js i have a component (Answer Component) like this:
<template>
<a class="quiz-input-choice" :class="{'quiz-input-choice--selected': answer.selected}"
#click="toggleSelect()" :selected="answer.selected">
<img :src="answer.image_path"/>
<p class="quiz-input-choice__description">{{answer.title}}</p>
</a>
</template>
<script>
export default {
props: ['answer'],
methods: {
toggleSelect() {
this.$parent.$emit('answer-selected', this.answer.id);
}
}
}
</script>
If in the parent (Question Component) I update the "selected" attribute of the element, this component will not be rerendered.
export default {
props: ['question'],
components: {QuizAnswer},
created: function () {
let _self = this;
this.$on('answer-selected', id => {
let i = _self.question.answers.map(item => item.id).indexOf(id);
let answer = _self.question.answers[i];
answer.selected = !answer.selected;
});
}
}
In Vue Developer Console, i checked that Answer component data are updated, so the answer is marked as selected. Anyway, is not rendered with the "quiz-input-choice--selected" class.
If, strangely, I update from the parent other attribute of the prop (for example (answer.title), then the child component is rendered correctly with also the class "quiz-input-choice--selected".
So i guess it's a problem of detecting changes from the child.
Thank you everybody for the answers.
I discovered the problem. The "selected" attribute of the answer was not present in the initial object, so Vue cannot make reactive that attribute.
https://v2.vuejs.org/v2/guide/reactivity.html
I solved making reactive that property in the parent component.
created() {
let self = this;
this.question.answers.forEach(function (answer) {
self.$set(answer, 'selected', false);
});
},
I think you have a structural issue here. You shouldn't submit an event to your parent, since the component is supposed to be self-contained.
What you can do however is emitting an event in the child component (Answer) that will be catch in the parent (Question).
Answer.vue
<template>
<a class="quiz-input-choice" :class="{'quiz-input-choice--selected': answer.selected}"
#click="toggleSelect()" :selected="answer.selected">
<img :src="answer.image_path"/>
<p class="quiz-input-choice__description">{{answer.title}}</p>
</a>
</template>
<script>
export default {
props: ['answer'],
methods: {
toggleSelect() {
this.$emit('answer-selected');
}
}
}
</script>
Question.vue
Your template will have be catching the event like this (I don't know where your answers are so I assume that you have a answers array) :
<answer
v-for="(answer, index) in answers"
:answer="answer"
#answer-selected="answerSelected(index)"
></answer>
And your script will look like this :
export default {
props: ['question'],
components: {QuizAnswer},
data() {
return {
answers: [],
selectedAnswer: -1,
};
},
watch: {
selectedAnswer(newIndex, oldIndex) {
if (oldIndex > -1 && this.answers.length > oldIndex) {
// Reset old value
this.answers[oldIndex].selected = false;
}
if (newIndex > -1 && this.answers.length > newIndex) {
// Set new value
this.answers[newIndex].selected = true;
}
},
},
methods: {
answerSelected(index) {
this.selectedAnswer = index;
},
},
};