I need help regarding how i can pass a function in *ngFor loop or any another suggestion ??
I have todo-list Component and a child todo-item component - I want to pass a function which will return a value- Please check the code below:
-- Todo List Component
`<div class="list-group">
<app-todo-item
*ngFor="let todo of todos; let i = index"
[todoItem]="todo"
[index]="i"></app-todo-item>
</div>`
-- Todo Item Component
`
<a
[routerLink]="index"
[routerLinkActive]="'list-group-item-warning'"
class="list-group-item">
{{ todo.name }}
<span class="badge badge-pill"
[ngClass]="{'badge-success': todo.status === 'active', 'badge-warning': todo.status === 'inactive'}">{{ todo.status }}</span>
<div class="option-group float-right">
<span class="badge badge-dark">2 days ago myFunction(date)</span>
</div>
</a>
`
Please let me know what possible way i can achieve this.
Thanks in advance
are you trying to pass the function to app-todo-item component?
if so you could use #Output from angular core
// import it inside your component
import { Output, EventEmitter } from '#angular/core'
// declare the function callback you want to recieve
#Output() callback = new EventEmitter();
// to make the callback send data back call, if you want to pass multiple fields put it all inside an object
this.callback.emit(datatobepassed)
// to make use of it do; you need to put $event or else function recieves undefined
<app-todo-item (callback)=”yourfunction($event)”>
// in your parent component
yourfunction(data: any)
{
// stuff
}
hope that helps
Related
Thank you in advance.
So I am fetching list of blog categories via API and rendering it in a list using v-for.
I also need to fetch the amount of blogs in every category and place them beside the category.
But the issue is I am calling a method that calls the api.
<li v-for="item in sidebar" :key="item.identifier">
<nuxt-link
tag="a"
:to="{
name: 'blog-page',
query: { category: item.identifier }
}"
>{{ $localize(item.translations).title }}
{{ getBlogCount(item.identifier) }}
</nuxt-link>
</li>
You know what it shows already example is Animals [Object Promise]
methods: {
async getBlogCount(identifier) {
axios
.get(
"https://example.com/posts?fields=created_at&filter[category.category_id.identifier]=" +
identifier +
"&meta=*"
)
.then(count => {
return count.data.meta.result_count;
});
}
}
What is the best way to handle this kinda thing?
You better call async methods in mounted or created hooks, and set the result to data, and then, use that data in template.
I'd suggest handling this in Script, instead of HTML Template.
What you can do is, depending on when the sidebar is initialized (maybe in the mounted hook), call getBlogCount method to fetch blog counts for each item in sidebar and store that may be in an array or object (or as a separate key-value pair to that same sidebar item object) and then use that data structure to display count values in the template.
Assuming the sidebar is populated in mounted hook and that it's an array of objects, you can do the following:
<template>
<li v-for="item in sidebar" :key="item.identifier">
<nuxt-link
tag="a"
:to="{
name: 'blog-page',
query: { category: item.identifier }
}"
>{{ $localize(item.translations).title }}
{{ item.blogCount }}
</nuxt-link>
</li>
</template>
<script>
mounted () {
// after the sidebar is populated
this.sidebar = this.sidebar.map(async item => {
item.blogCount = await this.getBlogCount(item.identifier)
return item
})
}
</script>
Hope this helps you out
I am using Vue and am trying to make live search. But on updating the content of search, it doesn't get updated.
Data do get update in array, when checked in dev tools. But DOM don't get updated.
template
<div class="dropdown">
<input type="text" v-model="input" placeholder="Search" #keyup="searching" data-toggle="dropdown">
<span class="caret"></span>
<ul class="dropdown-menu">
<li v-for="(data,index) in availSearchData" :key="index">
{{data.name}}
</li>
</ul>
</div>
method
searching() {
if (this.input) {
let url = this.domain + "search";
axios
.get(url, {
params: {
table: this.table,
data: this.input
}
})
.then(res => {
this.availSearchData = [];
res.data.forEach(doc => {
this.availSearchData.push(doc);
});
});
}
}
I don't know where I am doing wrong.
Please help out if possible.
To add an item to the back of an array and get it to be reactive in Vue, below is what worked for me:
this.$set(this.items,
this.items.length,
JSON.parse(JSON.stringify(this.item))
);
The this.$set is Vue's inbuilt array manipulation function that guarantees reactivity.
The this.items is the array, this.items.length (NOTE: it is items.length NOT items.length - 1) is to push a new index to the back of the array and finally, JSON.parse(JSON.stringify(this.item)) is to clone the this.item into a new object before pushing into the array. The cloning part may not be applicable to you and I used this in variables because all the variables are declared in my data() function.
Use a computed property in your component and use that for parsing the template like this
<li v-for="(data,index) in availSearch" :key="index">
{{data.name}}
</li>
and computed property will be then
availSearch() {
return this.availSearchData;
},
so this computed property always return the array if it is updated.
Also if your response is the array that you want to use exactly, try this
searching() {
if (this.input) {
let url = this.domain + "search";
axios
.get(url, {
params: {
table: this.table,
data: this.input
}
})
.then(res => {
this.availSearchData = [];
Vue.set(this, 'availSearchData', res.data);
});
}
}
Possible explanations for this might be:
You don't declare the property in the component and thus normal
reactivity doesn't work.
You are using index as the key in your array. This might confuse the
reactivity system, so it does not necessarily know if the item
changed. Try using the name of the item as the key instead.
Try calling your function from mounted hook. I think the problem is that you are trying to show data when the DOM is not rendered yet. By calling your function in mounted you get data back after DOM has been rendered.
mounted() {
this.searching();
}
from Vue website "mounted: Called after the instance has been mounted, where el is replaced by the newly created vm.$el. If the root instance is mounted to an in-document element, vm.$el will also be in-document when mounted is called."
I am a beginner of the vue.js. I can't understand scopedSlots and example in the guide.Can you give me a detailed answer，thanks very much!
I think it's best to illustrate with an example using plain JavaScript functions.
Think of the component like a function, eg
function todoList(todos) {
// render <ul>, loop todos, render <li> and todo.text
}
Now imagine that function is able to be passed an optional content rendering function named slot
function todoList(todos, slot) {
slot = slot || slotProps => {
// render slotProps.todo.text
}
// render <ul>
todos.forEach(todo => {
// render <li>
slot({ todo }) // call "slot" function
}
}
That function assigned to slot is the equivalent of
<slot v-bind:todo="todo">
<!-- Fallback content -->
{{ todo.text }}
</slot>
from the example.
So now when you call this function, you can optionally use something like
todoList(todos, slotProps => {
if (slotProps.todo.isCompleted) {
// render a checkmark, eg ✓
}
// render slotProps.todo.text
})
The function passed in here is the equivalent of
<template slot-scope="slotProps">
<!-- Define a custom template for todo items, using -->
<!-- `slotProps` to customize each todo. -->
<span v-if="slotProps.todo.isComplete">✓</span>
{{ slotProps.todo.text }}
</template>
in the example.
I have a list of items that don't get created until after an async call happens. I need to be able to get the getBoundingClientRect() of the first (or any) of the created items.
Take this code for instance:
<template>
<div v-if="loaded">
<div ref="myItems">
<div v-for="item in items">
<div>{{ item.name }}</div>
</div>
</div>
</div>
<div v-else>
Loading...
</div>
</template>
<script>
import axios from 'axios';
export default {
data() {
return {
items: []
}
},
created() {
axios.get('/url/with/some/data.json').then((response) => {
this.items = response.data;
this.loaded = true;
}, (error) => {
console.log('unable to load items');
});
},
mounted() {
// $refs is empty here
console.log(this.$refs);
// this.$refs.myItems is undefined
}
};
</script>
So, I'm trying to access the myItems ref in the mounted() method, but the this.$refs is empty {} at this point. So, therefore, I tried using a component watch, and various other methods to determine when I can read the ref value, but have been unsuccessful.
Anyone able to lead me in the right direction?
As always, thanks again!!
UPDATES
Added a this.$watch in the mounted() method and the $refs still come back as {}. I then added the updated() method to the code, then was able to access $refs there and it seemed to work. But, I don't know if this is the correct solution?
How does vuejs normally handle something like dynamically moving a div to an on-screen position based on async data? This is similar to what I'm trying to do, grab an element on screen once it has been rendered first (if it even should be rendered at all based on the async data), then access it to do something with it (move it to a position)?
Instead of doing on this.$refs.myItems during mounted, you can do it after the axios promise returns the the response.
you also update items and loaded, sou if you want to use watch, you can use those
A little late, maybe it helps someone.
The problem is, you're using v-if, which means the element with ref="myItems" doesn't exist yet. In your code this only happens when Axios resolves i.e. this.loaded.
A better approach would be to use a v-show.
<template>
<div>
<div v-show="loaded">
<div ref="myItems">
<div v-if="loaded">
<div v-for="item in items">
<div>{{ item.name }}</div>
</div>
</div>
</div>
</div>
<div v-show="!loaded">
Loading...
</div>
</div>
</template>
The difference is that an element with v-show will always be rendered and remain in the DOM; v-show only toggles the display CSS property of the element.
https://v2.vuejs.org/v2/guide/conditional.html#v-show
My first component (child component) like this :
<template>
...
</template>
<script>
export default {
...
methods: {
addPhoto() {
const data = { id_product: this.idProduct}
const item = this.idImage
this.$store.dispatch('addImage', data)
.then((response) => {
this.$parent.$options.methods.createImage(item, response)
});
},
}
}
</script>
If the method addPhoto called, it will call ajax and then it will get response ajax
I want to send response ajax and another parameter to method createImage. Method createImage is located in parent component (second component)
My second component (parent component) like this :
<template>
<div>
<ul class="list-inline list-photo">
<li v-for="item in items">
<div v-if="clicked[item]">
<img :src="image[item]" alt="">
<span class="fa fa-check-circle"></span>
</div>
<a v-else href="javascript:;" class="thumb thumb-upload"
title="Add Photo">
<span class="fa fa-plus fa-2x"></span>
</a>
</li>
</ul>
</div>
</template>
<script>
export default {
...
data() {
return {
items: [1,2,3,4,5],
clicked: [], // using an array because your items are numeric
test: null
}
},
methods: {
createImage(item, response) {
console.log(item)
this.$set(this.clicked, item, true)
this.test = item
},
}
}
</script>
If the code executed, it success call createImage method on parent component. The console log display value of item
But my problem is the data on parent component not success updated
How can I solve this problem?
You really should get in the habit of using events instead of directly accessing the parent component from a child.
In your case, it would be simple to emit an event in the then handler of the child's async request:
.then((response) => {
this.$emit('imageAdded', item);
});
And listen for it in the parent scope:
<child-component #itemAdded="createImage"></child-component>
That way, any component that uses that child component can react to its imageAdded event. Plus, you won't ever need to spend time debugging why the createImage method is firing when it's never being called in the Vue instance.
Your code isn't working because the way you are invoking the createImage method means that the this inside the function will not be referencing the parent component instance when it is called. So setting this.clicked or this.test will not affect the parent instance's data.
To call the parent component's function with the right context, you would need to do this:
this.$parent.createImage(item, response)