Nested vue.js instances/elements - javascript

This may sound like a real noob question, but I'm pretty new to MVVM... or even MVC in JS, so sorry in advance.
I'm playing about with vue.js, and loving the simplicity of it so far. But for what I am trying to do, I think I need to go about it a different way.
I want to nest Vue instances/elements inside each other, but of course, the parent will then use the child when it reads through the DOM on init.
For the sake of arguments, below is an example of what I mean, I am not doing anything like this, but this is the simplest way to example what I mean:
<body>
{{ message }}
<div id="another">
{{ message }}
</div>
</body>
Then my JS for example would be:
new Vue({
el: "body",
data: {
message: "I'm the parent"
}
});
new Vue({
el: "#another",
data: {
message: "I'm the child"
}
});
The outcome would be:
<body>
I'm the parent
<div id="another">
I'm the parent
</div>
</body>
Now I completely understand why it is doing this and in fact, it should do this, but my example is just trying to illustrate how I would do something like this?
In my real life project, I have a v-class on my body that changes when stuff happens in the body (in numerous places) but of course my body will also want other instances of vue that do other stuff.
how would I go about nesting? Is there feature in vue to deal with this? Do I need to deal with components? Or maybe, fetch the body from within a child element (e.g. like jQuery would with $("body")) then manipulate it within the Vue instance?
Hope this question isn't too stupid and someone can point me in the right direction.
Thanks


Think components.
http://vuejs.org/guide/components.html
Create a Vue instance on the body as you have above, but anything nested in that is a component. Pass data via props.


Passing in data via props is only one way to do it. Nesting components and inheriting from the parent works fine as well.
Example: http://jsfiddle.net/hajkrupo/3/
<encapsulated-component inline-template>
<header>
<cart-status></cart-status>
</header>
<cart></cart>
</encapsulated-component>


You can do this with <slot> tags. Here is an example.
1.So, first, you need to do is creating a basic layout component, like this.
You need to add <slot> tag whereever you want. Very important think is the name attribute on <slot> tag.
var basicLayout = Vue.component("basic-layout", {
template: `
<div class="basic-layout">
<header>
<slot name="header"></slot>
</header>
<main>
<slot></slot>
</main>
<footer>
<slot name="footer"></slot>
</footer>
</div>
`
});
2.Then create your custom component. I created myHeader component to show you, how it works.
var myHeader = Vue.component("my-header", {
template: `
<div class="header">
<ul>
<li>HOME</li>
<li>ABOUT</li>
<li>CONTACT</li>
</ul>
</div>
`
});
3.Put this sample code in your HTML file.
To put some content in current slot, just use the slot attribute in your component or your tag.
<div class="app">
<basic-layout>
<my-header slot="header"></my-header>
<p>Content in <main> tag</p>
<p slot="footer">Content in footer</p>
</basic-layout>
</div>
4.The result will be like this:
<div class="app">
<div class="basic-layout">
<header>
<div class="header">
<ul>
<li>HOME</li>
<li>ABOUT</li>
<li>CONTACT</li>
</ul>
</div>
</header>
<main>
<p>Content in <main> tag</p>
<main>
<footer>
<p>Content in footer</p>
</footer>
</div>
</div>
Please, see the documentation in official page of Vue.js
Just click link here for more info.
Here is example in jsfiddle

Related

Close navigation drawer after click on item?

I'm working on a University project and trying to implement a feature that allows the navigation drawer to close whenever I click on one of the items in it. However, I'm not sure how to handle this.
<template>
<div id="navigation-mobile">
<Searchbar class="search"/>
<ul v-for="item in tabs"
:key="item.path"
active-class
#click="$router.push(item.path)"
>
<li>{{item.name}}</li>
</ul>
<div class="mobile-footer">
<ul>
<li>About us</li>
<li>Contact us</li>
</ul>
</div>
</div>
</template>
And here's what I have in App.vue, which contains a part of the nav-drawer:
<template>
<v-app id="app">
<NavBarMobile v-if="mobileView"/>
<div class="content" :class="{'open': showNav}">
<div style="height:20px"></div>
<div id="navigation-icon" v-if="mobileView"
#click="showNav = !showNav">
<v-icon medium dark>menu</v-icon>
</div>
<NavBar v-if="!mobileView"></NavBar>
<v-content class="pa-0" transition="slide-x-transition"></v-content>
<Footer v-if="!mobileView"></Footer>
<router-view></router-view>
</div>
</v-app>
</template>
This is my code so far. I would like to use a #click, I think that would be the most efficient way to do that, but I don't know if I can, since I'm already using it. I'm not very good at programming. Any suggestions?
Here's the codepen: https://codesandbox.io/s/gameshelf-0209-jack-forked-zobe5
You can find the component in NavBarMobile.vue
Thanks in advance for taking the time to read this post!

There are a few ways you can achieve this. The simplest, in my opinion, would be to simply "watch" the $route object from within your App.vue:
export default {
// ...
watch: {
$route(to, from) {
this.showNav = false
}
}
}
The watch property on the Vue instance contains functions that will watch for changes to variables of the same name. Upon change, the function is run.
More on watchers and computed properties: https://v2.vuejs.org/v2/guide/computed.html
EDIT: Some extra info about reacting to Router changes: https://router.vuejs.org/guide/essentials/dynamic-matching.html#reacting-to-params-changes

Another way to achieve it is by emitting an event from the child component.
first point the click event to a method to handle your logic like so :
<ul v-for="item in tabs" :key="item.path" active-class #click="redirect(item.path)">
then add a method in your script to emit a custom event from your NavBarMobile component :
methods: {
redirect(path) {
this.$router.push(path)
this.$emit('change', false)
}
},
and finally listen for this event from the parent component:
<NavBarMobile v-if="mobileView" #change="showNav = $event"/>

Projecting ngFor template in <ng-content> isn't working

I'm working on an Angular 4 project and I'm stuck on a problem regarding templates.
Let me explain it better.
I have two components in my project:
SectionCompontent.ts
HomeCompontent.ts
These are the relative HTML templates
section.compontent.html
<div class="section">
<div class="cards">
<ng-content></ng-content>
</div>
</div>
home.compontent.html
<section>
<div *ngFor="let card of cards">
<span>{{card.title}}</span>
</div>
</section>
When I run this project, I expect to see the rendered content of *ngFor projected inside SectionComponent where <ng-content> is located.
Unfortunately, this is what I see on the DOM instead of <ng-content>:
<!--bindings={}-->
I added some static HTML tags like <p> and <h1> and they allowed it to work.
Can you help me solve this problem?
Thanks in advance.

Vue js error: Component template should contain exactly one root element

I don't know what the error is, so far I am testing through console log to check for changes after selecting a file (for uploading).
When I run $ npm run watch, i get the following error:
"Webpack is watching the files…
95% emitting
ERROR Failed to compile with 1 errors
19:42:29
error in ./resources/assets/js/components/File.vue
(Emitted value instead of an instance of Error) Vue template syntax
error:
Component template should contain exactly one root element. If you
are using v-if on multiple elements, use v-else-if to chain them
instead.
# ./resources/assets/js/components/AvatarUpload.vue 5:2-181 #
./resources/assets/js/app.js # multi ./resources/assets/js/app.js
./resources/assets/sass/app.scss"
My File.vue is
<template>
<div class="form-group">
<label for="avatar" class="control-label">Avatar</label>
<input type="file" v-on:change="fileChange" id="avatar">
<div class="help-block">
Help block here updated 4 🍸 ...
</div>
</div>
<div class="col-md-6">
<input type="hidden" name="avatar_id">
<img class="avatar" title="Current avatar">
</div>
</template>
<script>
export default{
methods: {
fileChange(){
console.log('Test of file input change')
}
}
}
</script>
Any ideas on how to solve this? What is actually the error?

Note This answer only applies to version 2.x of Vue. Version 3 has lifted this restriction.
You have two root elements in your template.
<div class="form-group">
...
</div>
<div class="col-md-6">
...
</div>
And you need one.
<div>
<div class="form-group">
...
</div>
<div class="col-md-6">
...
</div>
</div>
Essentially in Vue you must have only one root element in your templates.

For a more complete answer: http://www.compulsivecoders.com/tech/vuejs-component-template-should-contain-exactly-one-root-element/
But basically:
Currently, a VueJS template can contain only one root element (because of rendering issue)
In cases you really need to have two root elements because HTML structure does not allow you to create a wrapping parent element, you can use vue-fragment.
To install it:
npm install vue-fragment
To use it:
import Fragment from 'vue-fragment';
Vue.use(Fragment.Plugin);
// or
import { Plugin } from 'vue-fragment';
Vue.use(Plugin);
Then, in your component:
<template>
<fragment>
<tr class="hola">
...
</tr>
<tr class="hello">
...
</tr>
</fragment>
</template>

You need to wrap all the html into one single element.
<template>
<div>
<div class="form-group">
<label for="avatar" class="control-label">Avatar</label>
<input type="file" v-on:change="fileChange" id="avatar">
<div class="help-block">
Help block here updated 4 🍸 ...
</div>
</div>
<div class="col-md-6">
<input type="hidden" name="avatar_id">
<img class="avatar" title="Current avatar">
</div>
</div>
</template>
<script>
export default{
methods: {
fileChange(){
console.log('Test of file input change')
}
}
}
</script>

if, for any reasons, you don't want to add a wrapper (in my first case it was for <tr/> components), you can use a functionnal component.
Instead of having a single components/MyCompo.vue you will have few files in a components/MyCompo folder :
components/MyCompo/index.js
components/MyCompo/File.vue
components/MyCompo/Avatar.vue
With this structure, the way you call your component won't change.
components/MyCompo/index.js file content :
import File from './File';
import Avatar from './Avatar';
const commonSort=(a,b)=>b-a;
export default {
functional: true,
name: 'MyCompo',
props: [ 'someProp', 'plopProp' ],
render(createElement, context) {
return [
createElement( File, { props: Object.assign({light: true, sort: commonSort},context.props) } ),
createElement( Avatar, { props: Object.assign({light: false, sort: commonSort},context.props) } )
];
}
};
And if you have some function or data used in both templates, passed them as properties and that's it !
I let you imagine building list of components and so much features with this pattern.

Component template should contain exactly one root element. If you are using v-if on multiple elements, use v-else-if to chain them instead.
The right approach is
<template>
<div> <!-- The root -->
<p></p>
<p></p>
</div>
</template>
The wrong approach
<template> <!-- No root Element -->
<p></p>
<p></p>
</template>
Multi Root Components
The way around to that problem is using functional components, they are components where you have to pass no reactive data means component will not be watching for any data changes as well as not updating it self when something in parent component changes.
As this is a work around it comes with a price, functional components don't have any life cycle hooks passed to it, they are instance less as well you cannot refer to this anymore and everything is passed with context.
Here is how you can create a simple functional component.
Vue.component('my-component', {
// you must set functional as true
functional: true,
// Props are optional
props: {
// ...
},
// To compensate for the lack of an instance,
// we are now provided a 2nd context argument.
render: function (createElement, context) {
// ...
}
})
Now that we have covered functional components in some detail lets cover how to create multi root components, for that I am gonna present you with a generic example.
<template>
<ul>
<NavBarRoutes :routes="persistentNavRoutes"/>
<NavBarRoutes v-if="loggedIn" :routes="loggedInNavRoutes" />
<NavBarRoutes v-else :routes="loggedOutNavRoutes" />
</ul>
</template>
Now if we take a look at NavBarRoutes template
<template>
<li
v-for="route in routes"
:key="route.name"
>
<router-link :to="route">
{{ route.title }}
</router-link>
</li>
</template>
We cant do some thing like this we will be violating single root component restriction
Solution
Make this component functional and use render
{
functional: true,
render(h, { props }) {
return props.routes.map(route =>
<li key={route.name}>
<router-link to={route}>
{route.title}
</router-link>
</li>
)
}
Here you have it you have created a multi root component, Happy coding
Reference for more details visit: https://blog.carbonteq.com/vuejs-create-multi-root-components/

In addition to Bert and blobmaster responses:
If you need to remove the root element from the DOM you can exploit css and use display: value on the root element.

Bit of a misleading error.
What fixed it on my side was the fact that I had an additional </div> without an opening <div>.
I spotted it using Find/Replace on "div" which gave an odd number.

Wrap everything in one div and it will resolve the issue.
For example,
div
----div
----/div>
----div>
----/div>
/div
It is similar concept to React.js

For vue 3 they removed this constraint in template syntax :
<template>
<header>...</header>
<main v-bind="$attrs">...</main>
<footer>...</footer>
</template>
but it's still existing in JSX syntax :
Incorrect ❌
setup(props,{attrs}) {
return ()=>(
<header>...</header>
<main {..attrs}>...</main>
<footer>...</footer>
)
}
Correct ✔
setup(props,{attrs}) {
return ()=>(
<>
<header>...</header>
<main {..attrs}>...</main>
<footer>...</footer>
</>
)
}

I experienced this kind of issue and the issue was fixed by adding a main parent div tag or section if it is a section type of component.
<div class="list-of-friends">
<h3>Hello World</h3>
</div>

I was confused as I knew VueJS should only contain 1 root element and yet I was still getting this same "template syntax error Component template should contain exactly one root element..." error on an extremely simple component. Turns out I had just mispelled </template> as </tempate> and that was giving me this same error in a few files I copied and pasted. In summary, check your syntax for any mispellings in your component.

instead of using this
Vue.component('tabs', {
template: `
<div class="tabs">
<ul>
<li class="is-active"><a>Pictures</a></li>
<li><a>Music</a></li>
<li><a>Videos</a></li>
<li><a>Documents</a></li>
</ul>
</div>
<div class="tabs-content">
<slot></slot>
</div>
`,
});
you should use
Vue.component('tabs', {
template: `
<div>
<div class="tabs">
<ul>
<li class="is-active"><a>Pictures</a></li>
<li><a>Music</a></li>
<li><a>Videos</a></li>
<li><a>Documents</a></li>
</ul>
</div>
<div class="tabs-content">
<slot></slot>
</div>
</div>
`,
});

Just make sure that you have one root div and put everything inside this root
<div class="root">
<!--and put all child here --!>
<div class='child1'></div>
<div class='child2'></div>
</div>
and so on

Mixing Vue.js into existing SSR website?

Is it possible/viable to use Vue to create components that get instantiated onto custom tags rendered by e.g. a PHP application? Some kind of "custom elements light"?
It "works" if I mount the Vue instance onto the page root element, but - as far as I understand - Vue uses the whole page as a template in this case. And I imagine this could be a performance issue and cause trouble if other javascript code messes with the DOM.
The goal is to progressively replace legacy jQuery code. Is there an common approach for this problem?
Edit: Nesting these components is also a requirement. A simple example would be nested collapsibles.
Edit 2: Some fiddles to illustrate the problem.
A working solution based on riot.js:
https://jsfiddle.net/36xju9sh/
<div id="page">
<!-- This is supposed to show "This is a test." twice. -->
<test>
<test></test>
</test>
</div>
<script type="riot/tag">
<test>
<p>This is a test.</p>
<yield/>
</test>
</script>
<script>riot.mount('*')</script>
Two approaches using Vue.js:
https://jsfiddle.net/89ejjjsy/1/
HTML:
<div id="page">
<!-- This is supposed to show "This is a test." twice. -->
<test>
<test></test>
</test>
</div>
<script type="text/x-template" id="test-template">
<p>This is a test.</p>
<slot></slot>
</script>
Javascript:
Vue.config.ignoreCustomElements = ['test'];
// This won't hit the nested <test> element.
new Vue({
el:'test',
template: '#test-template',
});
// This does, but takes over the whole page.
Vue.component('test', {
template: '#test-template',
});
new Vue({
el: '#page',
});

You do not have to use whole page as Vue instance scope. It is more than ok to for example, use #comments-container as scope for comments component which will be nested somewhere on your page.
You can have multiple VueJS instances on one page.

Creating complex static Markup with ember.js

I am trying to render my application template, which is getting very complicated, so I want to split it up into separate <script type="text/x-handlebars">'s
I think I want to use the {{view}} helper, but I don't know. Let's say I have this:
<script type="text/x-handlebars" data-template-name="application">
<div id="wrapper" class="clearfix">
<hgroup>
<header>
<div class="logo"></div>
<h1 id="facilityName">{{facilityName}}</h1>
<div id="sessionInfo">
<a id="userName">{{user}}</a>
<a id="logOut" href="../logout">log out</a>
</div>
</header>
</hgroup>
{{view App.breadcrumbsView}}
</div>
</script>
And I want to load this next template inside of the one above:
<script type="text/x-handlebars" id="breadcrumbs">
<div id="breadcrumbs">
<p>
Network
{{#each breadcrumbObj}}
<span>></span><a {{bindAttr href="link"}}>{{name}}</a>
{{/each}}
</p>
</div>
</script>
Right now I am trying to do this with this code from my app.js
App.breadcrumbsView = Ember.View.create({
templateName: 'breadcrumbs',
breadcrumbObj: Util.breadcrumbs()
});
This is not working and I am getting Uncaught Error: assertion failed: Unable to find view at path 'App.breadcrumbsView'
Thanks

I think that you declared your App using var keyword. So it's not visible in handlebars template.
Change this
var App = Ember.Application.create();
To this
App = Ember.Application.create();
And you have to use extend instead of create when creating your views. Because ember will handle the object lifecycle like: create, destroy, add and remove binding etc.

#Marcio is right, you should .extend() and let the framework create it for you automatically by request. Furthermore when you extend the best practice is to use capitalized names like App.BreadcrumbsView.
See here a demo how it renders correctly doing it this way.
Hope it helps.

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