I have a parent component A, creating a child component B.
This child component's definition is imported using Loadable. In the following, component B is the Catalog.
Now I want to fetch some initial data before rendering this component, as it is described in the doc. Here's what I have :
const Catalog = Loadable.Map({
loader: {
Catalog: () => import('./Catalog'),
initialData: () => fetchCatalogInitialData(foo1, foo2),
},
loading: () => {return <div>foo</div>},
render(loaded, props) {
let Catalog = loaded.Catalog.default;
let initialData = loaded.initialData;
return <Catalog {...props} initialData={initialData} />;
},
});
I'd like fetchCatalogInitialData to be called with parameters, i.e a URL, a token, etc. Is this doable in a nice way?
As far as I know, this is not doable without forking the library. There are a few rejected PRs (example) that attempt to do this that the maintainer has rejected. To be fair, the rationale the author provides is as follows:
Your loader should be as static as possible or it's impossible to do things like server-side rendering reliably. I know that it is very limiting, but it's on purpose.
If you're not doing SSR, forking may be the best solution.
Related
I'm working in Nuxt3 and I've got a slightly unusual setup trying to watch or retrieve data from child components in a complex form that is structured as a multi-step wizard. It's obviously Vue underneath and I'm using the composition API.
My setup is that I have a page the wizard component is on, and that component has a prop that is an array of steps in the wizard. Each of these steps is some string fields for titles and labels and then a component type for the content. This way I can reuse existing form blocks in different ways. The key thing to understand is that the array of steps can be any length and contain any type of component.
Ideally, I'd like each child component to be unaware of being in the wizard so it can be reused elsewhere in the app. For example, a form that is one of the steps should handle its own validation and make public its state in a way the wizard component can read or watch.
The image below explains my basic setup.
The page includes this tag:
<Wizard :steps="steps" :object="project" #submit="createProject"/>
The Wizard loops over the steps to create each component.
<div v-for="(step) in steps" :key="step.name">
<component v-if="step.status === 'current'" :is="step.content.component" />
</div>
The data to setup the component with the right props for the wizard itself and the child component props.
const steps = ref([
{
name: 'overview',
title: t('overview'),
subTitle: t('projectCreateOverviewDescription'),
status: 'current',
invalid: true,
content: {
component: Overview,
props: null,
model: {}
}
},
{
name: 'members',
title: t('members'),
subTitle: t('projectCreateMembersDescription'),
status: 'upcoming',
invalid: false,
content: {
component: ThumbnailList,
props: {
objects: users,
title: t('users'),
objectNameSingular: t('user'),
objectNamePlural: t('users'),
So far I've tried to dynamically create references in the wizard component to watch the state of the children but those refs are always null. This concept of a null ref seems to be the accepted answer elsewhere when binding to known child components, but with this dynamic setup, it doesn't seem to be the right route.
interface StepRefs {
[key: string]: any
}
let stepRefs: StepRefs = {}
props.steps.forEach(step => {
stepRefs[step.name] = ref(null)
watch(() => stepRefs[step.name].value, (newValue, oldValue) => {
console.log(newValue)
console.log(oldValue)
}, { deep: true })
})
Can anyone direct me to the right approach to take for this setup? I have a lot of these wizards in different places in the app so a component approach is really attractive, but if it comes to it I'll abandon the idea and move that layer of logic to the pages to avoid the dynamic aspect.
To handle changes in child components I'd recommend to use events. You can have the children emit an event on change or completion, and the wizard is listening to events from all children and handling them respectively.
On the wizard subscribe to the event handler of the step component, and process the data coming from each step on completion (or whatever stage you need).
This way you don't need any special data type for the steps, they can just be an array. Simply use a ref to keep track of the current step. You don't even need a v-for, if you just display one step at a time. For a wizard navigation you might still need a v-for, but it would be much simpler. Please see a rough example below.
<div>
<stepComponent step="currentStep" #step-complete="handleStepComplete"/>
<div>
<wizardNavigationItemComponent v-for="step in steps" :active="step.name === currentStep.name" />
</div>
</div>
<script setup lang="ts">
const steps = step[/*your step data here*/]
const currentStepIndex = ref(0)
const currentStep = ref(steps[currentStepIndex.value])
function handleStepComplete(data) {
/* handle the data and move to next step */
currentStepIndex.value = currentStepIndex.value + 1 % steps.length
}
</script>
In the component you just need to define the event and emit it when the data is ready, to pass along the data:
<script setup lang="ts">
const emit = defineEmits<{
(event: "stepComplete", data: <your data type>): void
}>()
/* call emit in the component when its done / filled */
emit("stepComplete", data)
</script>
I hope this helps and can provide a viable path forward for you!
I've been tasked with implementing selectors in our redux application. Everything I'm reading online about redux selectors talks about React and how you can replace what is in mapStateToProps with a selector. What is the equivalent/where would i do this in a mithril app?
What is the equivalent/where would i do this in a mithril app?
Firstly, you don't need an equivalent, you can just use the exact same selectors that you would in a React application.
Where to call selectors?
You can call the selectors wherever you want, but I recommend calling them as close to where the data is used as possible. Don't call selectors in a component high up in the component hierarchy only to pass the data down via several components before they end up in a component that actually uses the data – unless you have a good reason to do so.
For most cases you can call the selectors inside a view-function, although you might come across cases where you need to call selectors in other lifecycle methods as well. In some applications you might also want to use selectors in m.render as well.
A couple of examples off the top of my head:
Inside the view function when creating DOM-elements
var LoggedinUserDetails = {
view: function () {
return m('', [
m('', getLoggedinUserName(store.getState())), // getLoggedinUserName is a selector
m('img', { src: getLoggedinUserImageUrl(store.getState()) }) // getLoggedinUserImageUrl is a selector
])
}
}
Inside the view function when creating Mithril components
var UserDetails = {
view: function (attrs) {
return m('', [
m('', attrs.user.name),
m('img', { src: attrs.user.imageUrl })
])
}
}
...
m(UserDetails, { user: getLoggedInUserDetails(store.getState()) }) // getLoggedInUserDetails is a selector
Inside m.render
In this example, we have a game that requires us to re-render the whole page after any change.
function onStateChange() {
var state = store.getState();
m.render(document.body, m(Game, {
map: getMap(state),
players: getPlayers(state),
visibleArea: getVisibleArea(state)
}));
}
// Receiving partial state updates from server via websockets
websocket.on('update-map', function (map) {
store.dispatch({ type: 'update-map', payload: map });
});
websocket.on('update-players', function (players) {
store.dispatch({ type: 'update-players', payload: players });
});
// Changing state based on user input
window.addEventListener('keydown', function (event) {
switch (event.key) {
case 'Enter':
store.dispatch({ type: 'move-visible-area-to-next-player' });
break;
}
});
I'm not familiar with Mithril, but Redux state selectors are independent from React. They are just functions that expect state and return a:
a slice of state
or data derived from state
For example, if I my Redux state has an entry named records containg a list of models:
{
records: [ ... ],
}
I could create a selector returning the length:
const numOfRecords = state => state.records.length
Or if my state also keeps track of a sortBy value:
const sortedRecords = state => state.records.sort(sortByFn(state.sortBy))
Selectors can be helpful to increase performance and reduce the need for updates. (reselect is a great module for this).
They are also great for developing modular pieces of code that depend on data stored in application state but don't really want to know where that data comes from.
So I'm creating what is at it's core a very simple CRUD-style application, using React + Redux. There is a collection of (lets call them) posts, with an API, and I want to be able to list those and then when the user clicks on one, go into a detail page about that post.
So I have a posts reducer. Originally I started using the approach taken from the redux real-world example. This maintains a cache of objects via an index reducer, and when you do a "get post" it checks the cache and if it's there, it returns that, else it makes the appropriate API call. When components mount they try to get things from this cache, and if they're not there they wait (return false) until they are.
Whilst this worked OK, for various reasons I now need to make this non-caching i.e. everytime I load the /posts/:postId page I need to get the post via the API.
I realise in the non-redux world you would just do a fetch() in the componentDidMount, and then setState() on that. But I want the posts stored in a reducer as other parts of the app may call actions that modify those posts (say for example a websocket or just a complex redux-connected component).
One approach I've seen people use is an "active" item in their reducer, like this example: https://github.com/rajaraodv/react-redux-blog/blob/master/public/src/reducers/reducer_posts.js
Whilst this is OK, it necessitates that each component that loads the active post must have a componentWillUnmount action to reset the active post (see resetMe: https://github.com/rajaraodv/react-redux-blog/blob/master/public/src/containers/PostDetailsContainer.js). If it did not reset the active post, it will be left hanging around for when the next post is displayed (it will probably flash for a short time whilst the API call is made, but it's still not nice). Generally forcing every page that wants to look at a post to do a resetMe() in a componentWillUnmount fells like a bad-smell.
So does anyone have any ideas or seen a good example of this? It seems such a simple case, I'm a bit surprised I can't find any material on it.
How to do it depends on your already existing reducers, but i'll just make a new one
reducers/post.js
import { GET_ALL_POSTS } from './../actions/posts';
export default (state = {
posts: []
}, action) => {
switch (action.type) {
case GET_ALL_POSTS:
return Object.assign({}, state, { posts: action.posts });
default:
return state;
}
};
It is very easy to understand, just fire an action to get all your posts and replace your previous posts with the new ones in the reducer.
Use componentDidMount to fire the GET_ALL_POSTS action, and use a boolean flag in the state to know if the posts where loaded or not, so you don't reload them every single time, only when the component mounts.
components/posts.jsx
import React from 'react';
export default class Posts extends React.Component {
constructor(props) {
super(props);
this.state = {
firstLoad: false
};
}
componendDidMount() {
if (!this.state.firstLoad) {
this.props.onGetAll();
this.setState({
firstLoad: true
});
}
}
// See how easy it is to refresh the lists of posts
refresh() {
this.props.onGetAll();
}
render () {
...
// Render your posts here
{ this.props.posts.map( ... ) }
...
}
}
We're just missing the container to pass the posts and the events to the component
containers/posts.js
import { connect } from 'react-redux';
import { getPosts } from './../actions/posts';
import Posts from './../components/posts.jsx';
export default connect(
state => ({ posts: state.posts }),
dispatch => ({ onGetAll: () => dispatch(getPosts()) })
);
This is a very simple pattern and I've used it on many applications
If you use react-router you can take advantage of onEnter hook.
I'm a novice to Meteor/React.js applications, and while I've been able to cobble together an app with multiple components by passing the App.jsx collections around as props, I can't seem to get individual components to handle their own collections. My rational is that some components need the collection fetched in one order, while others need the collection fetched in another. It seems silly to pass around a collection and then have to manipulate it internally to get the proper effect when a new sort is what's needed. My main App.jsx has:
App.propTypes = {
workdone:PropTypes.array.isRequired,
subjects:PropTypes.array.isRequired
};
export default createContainer(() => {
return {
workdone: WorkDoneCollection.find({},{sort:{createdAt:-1}}).fetch(),
subjects: SubjectCollection.find({},{sort:{subject:1}}).fetch()
};
}, App);
and if I pass the props.workdone on to another component everything works fine. On the other hand if I try a set up an independent collection in the other component, like this:
WorkSummary.propTypes = {
workdone:PropTypes.array
};
export default createContainer(() => {
return {
workdone: WorkDoneCollection.find({},{sort:{createdAt:1}}).fetch()
};
}, WorkSummary);
the workdone property is undefined.
I faced a problem, I solve it by cookies but I want to solve the problem without cookies. I have a component which called app-header and It has another component which called outmodal.
Now, My first Vue instance require component app-header.
var vue = new Vue({
el : "html",
data : {
title : "Site Title",
description : "description of page",
keywords : "my keywords",
view : "home",
login : "login"
},
components:{
"app-header" :require("../../components/header"),
"app-footer" :require("../../components/footer"),
"home" :require("../../views/home")
},
});
code of app-header
var Vue = require("vue");
Vue.partial("login",require("../../partials/login.html"));
Vue.partial("logged",require("../../partials/logged.html"));
module.exports = {
template : require("./template.html"),
replace : true,
components : {
outmodal : require("../outmodal")
},
props : ['login']
}
code of outmodal
var Vue = require("vue");
Vue.partial("loginModal",require("../../partials/loginModal.html"));
module.exports = {
template : require("./template.html"),
replace : true,
props : ['name'],
data : function () {
return {
userLogin : { mail : "", password : "", remember : ""}
}
},
methods : {
formSubmit : function(e){
e.preventDefault();
this.$http.post("http://example.com/auth/login",{ "email": this.userLogin.mail , "password": this.userLogin.password },function(data,status,request){
$.cookie("site_token",data.token,{expires : 1})
}).error(function(data,status,request){
});
}
}, ready : function(){
console.log("it works")
}
}
In outmodal component I connect the API and I check the login, If login will be succesfull, I want to change value of login variable in my Vue instance. I use web pack to build all requires. So I don't know how can I data binding between these files.
How can I solve It? I
The Best Solution which I found
For 0.12
http://012.vuejs.org/guide/components.html#Inheriting_Parent_Scope
for 1.0
http://v1.vuejs.org/guide/components.html#Parent-Child-Communication
for 2.0
https://v2.vuejs.org/v2/guide/components.html#Composing-Components (use props to one-way bind data from parent to child)
There are several ways of doing it, and some are mentioned in other answers:
Use props on components
Use v-model attribute
Use the sync modifier (for Vue 2.0)
Use v-model arguments (for Vue 3.0)
Use Pinia
Here are some details to the methods that are available:
1.) Use props on components
Props should ideally only be used to pass data down into a component and events should pass data back up. This is the way the system was intended. (Use either v-model or sync modifier as "shorthands")
Props and events are easy to use and are the ideal way to solve most common problems.
Using props for two-way binding is not usually advised but possible, by passing an object or array you can change a property of that object and it will be observed in both child and parent without Vue printing a warning in the console.
Because of how Vue observes changes all properties need to be available on an object or they will not be reactive.
If any properties are added after Vue has finished making them observable 'set' will have to be used.
//Normal usage
Vue.set(aVariable, 'aNewProp', 42);
//This is how to use it in Nuxt
this.$set(this.historyEntry, 'date', new Date());
The object will be reactive for both component and the parent:
I you pass an object/array as a prop, it's two-way syncing automatically - change data in the
child, it is changed in the parent.
If you pass simple values (strings, numbers)
via props, you have to explicitly use the .sync modifier
As quoted from --> https://stackoverflow.com/a/35723888/1087372
2.) Use v-model attribute
The v-model attribute is syntactic sugar that enables easy two-way binding between parent and child. It does the same thing as the sync modifier does only it uses a specific prop and a specific event for the binding
This:
<input v-model="searchText">
is the same as this:
<input
v-bind:value="searchText"
v-on:input="searchText = $event.target.value"
>
Where the prop must be value and the event must be input
3.) Use the sync modifier (for Vue 2.0)
The sync modifier is also syntactic sugar and does the same as v-model, just that the prop and event names are set by whatever is being used.
In the parent it can be used as follows:
<text-document v-bind:title.sync="doc.title"></text-document>
From the child an event can be emitted to notify the parent of any changes:
this.$emit('update:title', newTitle)
4.) Use v-model arguments (for Vue 3.0)
In Vue 3.x the sync modifier was removed.
Instead you can use v-model arguments which solve the same problem
<ChildComponent v-model:title="pageTitle" />
<!-- would be shorthand for: -->
<ChildComponent :title="pageTitle" #update:title="pageTitle = $event" />
5.) Use Pinia (or Vuex)
As of now Pinia is the official recommended state manager/data store
Pinia is a store library for Vue, it allows you to share a state across components/pages.
By using the Pinia store it is easier to see the flow of data mutations and they are explicitly defined. By using the vue developer tools it is easy to debug and rollback changes that were made.
This approach needs a bit more boilerplate, but if used throughout a project it becomes a much cleaner way to define how changes are made and from where.
Take a look at their getting started section
**In case of legacy projects** :
If your project already uses Vuex, you can keep on using it.
Vuex 3 and 4 will still be maintained. However, it's unlikely to add new functionalities to it. Vuex and Pinia can be installed in the same project. If you're migrating existing Vuex app to Pinia, it might be a suitable option. However, if you're planning to start a new project, we highly recommend using Pinia instead.
i found this one to be more accurate.
https://v2.vuejs.org/v2/guide/components.html#sync-Modifier
only in 2.3.0+ tho.
and honestly it's still not good enough. should simply be a easy option for 'two-way' data binding. so none of these options is good.
try using vuex instead. they have more options for such purpose.
https://vuex.vuejs.org/en/state.html
I would prefer event-driven updates as recommended in the documentation. However, I was limited by the existing ("third-party") component already using props and $emit. This component is my grandchild. The following is my solution (passing value through child using props, sync and computed value with $emit.
Comments are welcome.
Value can be modified in parent and grandchild without error:
Grandchild (simplified third-party component):
<template>
<div v-show="value">{{ value}}</div>
<button #click="closeBox">Close</button>
</template>
<script>
export default {
props: {
value: null
},
methods: {
closeBox() {
this.$emit('update:value', null);
}
}
}
</script>
Child:
<template>
<grandchild-component :value.sync="passedValue" />
</template>
<script>
export default {
props: {
value: null
},
computed: {
passedValue: {
get() {
return this.value;
},
set(newVal) {
this.$emit('update:value', newVal);
}
}
}
}
</script>
Parent:
<template>
<child-component :value.sync="value" />
</template>
<script>
export default {
data() {
return {
value: null,
}
},
// ... e.g. method setting/modifying the value
}
</script>