Because of consuming logic from a separate, server-side templating engine, I find myself working with native Web Components / Custom Elements (built in Vue v3) rather than a more "normal" Vue app.
TL/DR: If I override child CustomElement attributes during parent $onMounted() (or shortly after), it breaks the child's reactivity, but if I wait 1sec everything's fine... Is there a way to get it working properly?
The setup is something like the below, where the HTML is generated at run-time:
<!-- Runtime-generated index.html -->
<outer-custom-element>
<!-- Content populated dynamically by a separate SSR templating engine -->
<inner-custom-element myboolprop otherprop="5" />
<inner-custom-element otherprop="5" />
</outer-custom-element>
Both inner and outer components are Vue-implemented Custom Elements, and the outer component uses a <slot> to transclude the content in its template:
<!-- OuterCustomElement Vue template -->
<div class="outer-el">
<div class="everybody-loves-divs">
<slot></slot>
</div>
</div>
Because the server templating engine controls the inner content, these InnerVueCustomElements are not (and as far as I know cannot be) bound directly to Vue data on the OuterVueCustomElement: If the parent component needs to know what's inside it, we'll have to hack around with DOM and HTMLSlotElement.assignedElements() to interact with the inner components. Yes it's ugly and limiting, but seems pretty unavoidable to me if we have to accept something other than Vue controls the layout of this section of the HTML?
So anyway the problem arises if we try to update inner component props immediately after outer component mount, something like this:
/* OuterCustomElement Vue script */
function $onMounted(props) {
// (Some combination of querySelectorAll and slot assignedElements)
const innerEls: HTMLElement[] = listInnerCustomElements();
// This will permanently break otherprop reactivity on the element:
// innerEls[0].setAttribute("otherprop", "0");
// This will not (works fine):
setTimeout(() => innerEls[0].setAttribute("otherprop", "0"), 1000);
}
setTimeout(..., 10) and Vue's nextTick(...) suffer from the same problem as the immediate call: The inner component will not respond to the change. However if we wait a decent amount of time, this update goes through fine and nothing breaks.
I know this is a long way removed from normal state/render lifecycle management good practice within an all-Vue app, but for a Web Component / Custom Element it should be possible right?
Can anybody suggest what's breaking here and how to avoid it?
Related
Im facing a problem for my VUE app, Im using the vue Router to navigate to my component
In my Header component I use router-link to navigate to a Home component
The problem is :
In my Header component I would like a checkBox (a boolean variable) that change the content of my Home component (rendered in the router-view) like a v-if that would check the boolean variable in the Header
Here is my App.vue template I was trying to solve the problem through emits but Im Kinda stuck for passing data inside a component (inside the router-view)
<template>
<div class="content">
<HeaderComponent #eventCheckBox="handleCheckBox" />
<router-view />
<FooterComponent />
</div>
Do you guys have already faced this issue, is there a way to do it the classic way or should I try plugins like Portal or Teleport ?
Portal and Teleport are the same, just a different name (teleport in Vue3, being the official name).
As of the rest of the question, this explains it very well: https://stackoverflow.com/a/49702934/8816585
Mainly, you need to see if you need to use a store like Pinia (recommended one) and Vuex. Most of the time, you could use a parent/child relationship. Here is another article explaining when you would need something like that: https://markus.oberlehner.net/blog/should-i-store-this-data-in-vuex/#alternatives-to-storing-data-in-vuex
In Vue3, you could even not use a store and rely solely on the singleton pattern + composables (again, a lot of articles are available for that one).
TLDR: use your Vue devtools and inspect the state flowing.
If you need more, reach for more powerful tools.
I'm trying to show an activity indicator, when I go from one page to another. The target page contains many components within it, and it takes time to load. that's why I need some way to listen when all the child components are loaded, and at that moment tell my variable isBussy to be false
<template>
<StackLayout>
<ActivityIndicator :busy="isBussy" v-if="isBussy" />
<StackLayout v-else>
<Component1 />
<Component2 />
<Component3 />
<Component4 />
</StackLayout>
<StackLayout>
</template>
<script>
import Component1 from '~/components/Component1'
import Component2 from '~/components/Component2'
import Component3 from '~/components/Component3'
import Component4 from '~/components/Component4'
export default {
data() {
return {
isBussy: true
}
},
mounted() {
this.$nextTick(function() {
// Code that will run only after the
// entire view has been re-rendered
this.isBussy = false
})
}
}
</script>
this code does not work, since once the navigation is indicated from the previous page with:
#tap="$goto('otherPage', { props: { foo: bar } })"
it remains stuck on the initial page, and all the components begin to load in the background of the destination page, but without displaying the parent page, changing to this, only when the whole process ends, and never show/hide the activity indicator as expected.
By the way this expected behavior works perfectly when i do request and process them with Promises, then I turn on or off a variable in the state and it works. but I can not replicate that behavior in the navigation between pages and listen to load all the components
EDIT
Finally I achieved the desired behavior with a little trick I found on the internet
mounted() {
setTimeout(() => {
this.isBussy = false
}, 500)
},
this causes that the rendering of all the children components is delayed only a little, so that the activity indicator is shown, but not too much to produce that none of the components contained in the else block is detected and begin to rendering
There are two main ideas to understand here I think. I'll describe both.
1. General technique to Fetch Data without blocking render
It sounds like you understand this concept at the parent component level but then are asking how to do something very similar for the child components that this page contains.
The way I handle this, is in my component, I have my data default to an isLoading state. Then, in beforeMount() or mounted(), I perform my asynchronous actions and make necessary changes to my page's data.
The problem becomes entirely recursive when we look at child components. You want to make sure your child components are rendering and that any long running data fetching that needs to occur within their implementation will simply cause them to re-render once that fetching is complete.
Here is a working example: https://codesandbox.io/embed/r4o56o3olp
This example uses Nuxt. Aside from the addition fetch() and asyncData() methods, the rest of the Vue lifecycle hooks are the same here.
I use new Promise and setTimeout to demonstrate an operation that would use promises and be asynchronous. (e.g. axios.get(..))
The About page loads, and the beforeMount() lifecycle hook performs the asynchronous fetching in a way that doesn't block the page from rendering.
I use the beforeMount() hook because, according to here ( https://alligator.io/vuejs/component-lifecycle/ ), it is the first lifecycle hook that we have access to once the page's data is reactive. (So modifying this.myDataProp would trigger a re-render if {{ myDataProp }} was used in the template).
I also included a child component where I purposely made its data take twice as long to load. Since I again, am letting the component render immediately, and then I handle the fetching/updating of data in an appropriate lifecycle hook, I can manage when the end-user perceives a page to be loaded.
In my working example, the LongLoadingComponent did the same exact technique as the About page.
Once you see how to use beforeMount() or mounted() to fetch data and then update state, I think the trick is to take a moment and really think about the default state of your component. When it first renders, what should the user see before any of it's data fetching/long-running operations are completed?
Once you determine what your default (not yet loaded) component should look like, try getting that to render on your screen, and secondarily add in the logic that fetches and updates state data.
2. Listening for when a Child Component is finished rendering from a parent component
This makes use of the above technique, but includes the usage of the updated() hook and emitting a custom event ( https://v2.vuejs.org/v2/guide/components-custom-events.html
)
If you really want to listen for when your child components are finished rendering, you can $emit a custom event in your updated() hook. Perhaps something like this (in one of your child components)
if (this.dataLoaded) { this.$emit('loadedAndRendered') }
So when the child's async operations are done, it can flip it's dataLoaded property to true. If dataLoaded is used in the child's <template> somewhere, then the component should re-render (for it's "finished" state). When the child re-renders, the updated() hook should trigger. (again, see: https://alligator.io/vuejs/component-lifecycle/ ) I included the if (this.dataLoaded) part just to handle case where updated() hook might be called during intermediate data updates. (We only want to emit loadedAndRendered event if child is finished loading data/updating.)
3. Other caveats about universal nuxt applications
It wasn't until after I wrote this answer that I realized you aren't using Nuxt. However I'm adding this in case other Nuxt users happen to come across this.
I'm adding this section just because it took some focused hands-on time for me to wrap my head around. A Nuxt Universal Application does both server-side and client-side rendering. Understanding when something renders on the client vs when it was rendered on the server was a little difficult for me at first. In the working example I linked above, when you visit the about page you can also see if that component was fetched from the server or if it was just rendered by the client.
I'd recommend playing with a Page's fetch() and asyncData() methods and see how it impacts when certain things render on your screen. ( https://nuxtjs.org/api/pages-fetch/ ) ( https://nuxtjs.org/api/ ). Seeing what these methods are useful for helps me also identify what they are not useful for.
If you're using a Vuex store, I'd recommend seeing what happens when you refresh a page or use instead of a to navigate between pages. (Seeing something like the SSR schema diagram can be helpful here: https://nuxtjs.org/guide#schema )
..I have yet to fully appreciate the details of the bundling and delivery behavior that Webpack provides for a Universal Nuxt app (See right side of diagram here: https://medium.freecodecamp.org/universal-application-code-structure-in-nuxt-js-4cd014cc0baa )
Somehow I still can't wrap my head around some core vue concepts.
I have made some simple webpage using phalcon. Created it so, that it would work without JS and now is the time to add some bells and whistles - ajax queries and the like, for the user experience to be better.
I wanted to do everything using vue, to see how it all adds up. But after hours of googling I still can't find solution for the simplest of tasks.
Say: I want to get a text paragraph in a series of <li>-s and change it somewhat. Maybe make excerpt of it and add 'see more' button behind it. Now, in jQuery I would just iterate with each() and perform the tasks. With vue targeting set of DOM elements is much harder for me, probably because of whole paradigm being "the other way round".
I know I could iterate with v-for, but these elements are already in the DOM, taken from the database and templated with volt. I had even this wild idea of creating .js files from phalcon, but it would completely negate my strategy of making functional webpage first and then enhance it progressively.
Frankly speaking I feel like I'm overcomplicating for the sake of it, right now. Is vue even fit for a project like this, or is it exclusively a tool to build app from the ground up?
Vue's templating is client-side, which means if you are delivering an already templated html page (by your backend) there is little vue can still do for you. Vue needs data, not DOM elements to build its viewmodels.
This becomes pretty obvious when building a single page application for example, which would be rendered only on the client-side. You'd simply load the data asynchronously from a backend api (REST for example) and then do all the rendering on the client.
As far as I understand your usecase you want to mix client and server side rendering, rendering most of the non-interactable content using your backend's templating engine and adding some interactivity using vue. In this case you'll need to add some vue components (with their own rendering logic) to your backend template and pass data to that component using vue's data-binding.
Here's an example:
...
<div id="app">
<my-vue-list :products="{% products %}"></my-vue-list>
</div>
...
And in your JS:
var app = new Vue({
el: '#app',
data: {
components: {MyVueList} // You will have to register all the components you want to use here
}
})
Vue provides the ref attribute for registering a reference to a dom element or child component:
// accessible via this.$refs.foo
<li ref="foo">...</li>
Do note, however, that refs are not reactive, as stated in the docs:
$refs is also non-reactive, therefore you should not attempt to use it in templates for data-binding.
I have a listing/detail use case, where the user can double-click an item in a product list, go to the detail screen to edit and then go back to the listing screen when they're done. I've already done this using the dynamic components technique described here: https://v2.vuejs.org/v2/guide/components.html#Dynamic-Components. But now that I'm planning to use vue-router elsewhere in the application, I'd like to refactor this to use routing instead. With my dynamic components technique, I used keep-alive to ensure that when the user switched back to the list view, the same selection was present as before the edit. But it seems to me that with routing the product list component would be re-rendered, which is not what I want.
Now, it looks like router-view can be wrapped in keep-alive, which would solve one problem but introduce lots of others, as I only want that route kept alive, not all of them (and at present I'm just using a single top level router-view). Vue 2.1 has clearly done something to address this by introducing include and exclude parameters for router-view. But I don't really want to do this either, as it seems very clunky to have to declare up front in my main page all the routes which should or shouldn't use keep-alive. It would be much neater to declare whether I want keep-alive at the point I'm configuring the route (i.e., in the routes array). So what's my best option?
You can specify the route you want to keep alive , like:
<keep-alive include="home">
<router-view/>
</keep-alive>
In this case, only home route will be kept alive
Vue 3
<router-view v-slot="{ Component }">
<keep-alive>
<component :is="Component" />
</keep-alive>
</router-view>
Exactly as is, you don't need a Component attribute in the App.vue. Also your this'll work even if your components don't have a name property specified.
I had a similar problem and looked at Vuex but decided it would require too much changes/additions in my code to add to the project.
I found this library https://www.npmjs.com/package/vue-save-state which solved the problem for me, keeping the state of 1 component synchronized with localStorage, and it only took a few minutes and a few lines of code (all documented in the Github page of the package).
One solution without localStorage:
import {Component, Provide, Vue} from "vue-property-decorator";
#Component
export default class Counter extends Vue {
#Provide() count = 0
/**
* HERE
*/
beforeDestroy() {
Object.getPrototypeOf(this).constructor.STATE = this;
}
/**
* AND HERE
*/
beforeMount() {
const state = Object.getPrototypeOf(this).constructor.STATE;
Object.entries(state || {})
.filter(([k, v]) => /^[^$_]+$/.test(k) && typeof v !== "function")
.forEach(([k]) => this[k] = state[k]);
}
}
What seems to me is you are looking for some kind of state management. If you have data which is shared by multiple components and you want to render component in different order, but dont want to load data again for each component.
This works like following:
Vue offers a simple state management, but I will recommend to use Vuex which is a standard for state management among vue community.
Is it possible to add an Aurelia top level component without the router?
The goal is to create a component without the router since my application doesn't need any url based navigation.
From what I can tell Aurelia seems to take you down a path where components are instantiated via routing based on how the component is registered with the router.
Instead I would like to just add markup for the top level component on the main index.html page:
<my-component bind.current="'123456'"></my-component>
I would like define components without a router and only use the templating and data binding capabilities of Aurelia.
Is that possible?
Tried this in index.html (inside the body tag of the default project)
<require from='./dist/my-component'></require>
<my-component></my-component>
But it does not seem to pick it up. Ideally I would like to just define it in markup on a page served from the server since it would enable me to sett attributes dynamically on the elements
<my-component current.bind={{someServerGeneratedId}}></my-component>
In the above I would use a templating framework like mustache to dynamically render the Aurelia when the page is served from the server.
I could wrap the component in another "landing" component, but that makes it hard to benefit from setting things up with server generated bindings.
UPDATE:
Per Rob's response: https://github.com/aurelia/framework/issues/175#issuecomment-126965417
- He is expecting to add the ability to add a root component to the landing page in a future release. I understand there are ways to not use the router, but it still depends on pulling in a partial view during bootstrapping of the application. This does not use the router directly, but conceptually this is really just an implied/convention based client side nav. In the end there is a client side request to pull in the view, which means I can't generate the html dynamically from the initial server response.
Yes you can do this very easily without the router. Just remove the router configuration from your app.js and in app.html remove the router code there as well.
I think the issue you are running in to is that you are specifying the dist folder again in your index.html. You should just reference it like this -
<require from="my-component"></require>
<my-component current.bind="someServerGeneratedId"></my-component>
This will bind up correctly.
I guess you're missunderstanding the route concept here.
At the time of writing, Aurelia's index.html page is your initial page where you put your "loading" stuff and where Aurelia bootstraps the entire app.
So, you can't put a custom component directly on it, but that should not be a problem.
If you don't change any configuration on Aurelia, it will look for your app.html to bootstrap your app, and there you can have anything you want (routes or not, doesn't matter). So, you should put your component there, beside the other tags/components/etc you need.
I've made a plunker without any routing and with a custom component in the app.html, and something simulating what you need.
<template>
<require from='./my-component'></require>
<my-component current.bind="serverGeneratedID"></my-component>
</template>
http://plnkr.co/edit/mLb8Ym638b4V2e9LDp0A?p=preview
If you need anything else, comment here and I'll try to go further.