i have a tree of objects that im showing using vue. Each node in the tree can be of a specific type, and users can click through the tree from node to node. Most nodes can be rendered the same, using a default template. But some nodes require drastically different rendering. So I figure id use specific components for each node type.
I know I can use the "component is=" method, but how can I load specific components based on a node's type, or if there isnt a specific component for that type, load a default component. Is there some way to check if a component exists? Or should I maintain some array with all types that need a specific component?
As you mentioned, you could use <component :is>. Here's a possible implementation:
You can call a function getNodeComponentByType(node) which returns a specific type of component based on the current node.
E.g.In your template (i.e. if this is how you render tree nodes)
<component v-for="node in nodes" :is="getNodeComponentByType(node)">
and subsequently implement this method as shown:
var vm = new Vue({
el: '#app,
data: {
...
},
methods: {
getNodeComponentByType: function (node) {
switch(node.type) {
case 'typeA' : return ATypeTreeNodeComponent;
case 'typeB': return BTypeTreeNodeComponent;
default: return defaultTreeNodeComponent;
}
}
},
components: {
ATypeTreeNodeComponent,
BTypeTreeNodeComponent,
defaultTreeNodeComponent
...
}
})
Hope this helps.
Related
In vue.js what is the right way to edit prop without changing parent data?
What I mean by that is whenever we pass any property from parent to child in vue.js then if we make any change to that property in child component then the change is also reflected in parent's component.
Is there any way in vue.js to make a local copy of passed property in a child?
I googled this but everywhere it is written that we can achieve this by doing this.
props:["user"],
data(){
return {
localUser: Object.assign({}, this.user)
}
}
here the user is passed an object and I am creating a copy of it in local user but it doesn't work at all, the local user is undefined.
Have you encountered a scenario like this where you have to make changes to a parent property in child component without affecting the state of parent component i.e- making your own copy in child and then edit it?
Any insights on this will be helpful.
I have also read somewhere that in In vue#2.3.3，when we want to pass a prop from Father to Child component, we need to manually create a local data to save the prop, that makes lots of useless works.
we can maually create the local data like this :
props: ['initialCounter'],
data: function () {
return { counter: this.initialCounter }
}
but this is not working in my case as well.
I am using vue cli 3.0.1 for the developemnt purpose.
Here is my code for the same.
In my application I have a list view.
When user clicks on the See Focused View button user is redirected to below mentioned view i.e is actaully a bootstrap - modal view.
Here user can edit the value of Name, but as I am passing name here as a property from aprent component so editing it here causes it to update on parent component as well i.e in the list view as well.
In your fiddle, the child component is using Object.assign() to create a copy of data, which is an array of objects. However, this only creates a shallow copy, so the array elements would still refer to the original instances, leading to the behavior you're seeing.
A few solutions to deep copy the array:
Use JSON.parse(JSON.stringify(this.data)), which works reasonably well for primitive object properties (String, Number, BigInt, Boolean, undefined, and null):
data() {
return {
local_data: JSON.parse(JSON.stringify(this.data))
}
}
(demo 1)
Map the objects into new ones, which works well if the depth is only 1 (nested arrays/objects will still be shallow copied):
data() {
return {
local_data: this.data.map(x => ({...x}))
}
}
(demo 2)
Use a utility library, such as lodash's cloneDeep:
data() {
return {
local_data: _.cloneDeep(this.data)
}
}
(demo 3)
I have a menu of topics (e.g. "About us", "Support") and I want to be able to tell what topic is active right now. When a topic is clicked it will become the active one. Think of it as a substitute for a router that will set an active route. This is not possible in my case since I'm working in SharePoint 2010... in a content editor. So I made the decision to have an activeTopic variable in my Vue instance.
The Vue instance
new Vue({
el: '#app',
data: {
activeTopic: '',
}
});
This is because the activeTopic has to update another component and show some data based on the active topic. Like a router showing a child route.
The topic component
Vue.component('topic', {
props: ["title"],
methods: {
setActiveTopic: function (title) {
activeTopic = title;
},
isActiveTopic: function (title) {
return activeTopic == title;
}
},
template: `
<div v-bind:class="{active: isActiveTopic(title)}" v-on:click="setActiveTopic(title)">
<p v-text="title"></p>
</div>
`
});
The setActiveTopic function works as it should when I click it; it updates the activeTopic. But the isActiveTopic function gives me this error:
Error in render: "ReferenceError: activeTopic is not defined"
What I don't understand is that I can edit the activeTopic variable but I can't make a comparison? I've tried setting a default value but it still says it is undefined.
activeTopic should be assigned to the Vue component by setting and reading this.activeTopic. As is, you have two independent activeTopic variables scoped within each of your component methods.
You'll also want to include activeTopic in the component's data block, rather than on the Vue object itself, since it's specific to the component.
(If there's a reason to put that variable on the Vue object you would either want to pass it down to the component as a prop, or else access it directly as Vue.activeTopic instead of this.activeTopic. I'm honestly not certain whether Vue would treat that last structure as a reactive value within components -- I've never had a reason to try that, and can't think of a situation where that'd be a reasonable architecture.)
Vue.component('topic', {
props: ["title"],
data() { return {
activeTopic: ''
}},
methods: {
setActiveTopic(title) {
this.activeTopic = title;
},
isActiveTopic(title) {
return this.activeTopic == title;
}
},
template: `
<div v-bind:class="{active: isActiveTopic(title)}" v-on:click="setActiveTopic(title)">
<p v-text="title"></p>
</div>
`
});
I am new to Vue, and have seen data being defined as an object in several examples.
But apparently, as per the documentation, you have to use data as a function that returns an object.
This is to ensure that all instances will have it's own version of the data object, and is not shared with all instances.
Instead of
data: {
count: 0
}
use
data: function () {
return {
count: 0
}
}
However I still don't know why in one of my component, data as an object worked, and in a child component with it's own data as an object, I got the error count is undefined;
I am assuming, the root element, (defined by new Vue({}) has to be a singleton, and is not intended to have several instances.
And since components, can have instances, the data in that needs to be defined as a function.
I'm new to Vue.js. I followed the tutorial here - https://coligo.io/dynamic-components-in-vuejs/ - on dynamic components, to give me a dynamic layout I liked, for listing products and allowing the user to switch to an edit view when they click on one of the products in the table. So, I have a 'list-products' component and an 'edit-product' component, and which one is displayed is dependent on the state of 'currentView' in the main Vue instance.
<div id="content">
<keep-alive>
<component :is="currentView"></component>
</keep-alive>
</div>
The switching is all working fine when currentView is changed. What I haven't got figured out is how best to pass the product information to the edit component such that it ends up as data. I suppose the list and edit components are two sibling components of the main Vue instance, instantiated at the same time. What I need to do is when I click on a row in listing table, have the product object used for building that row made available to the edit component. I'm not sure how I do that (at least, in a proper Vue way). When the displayed component is switched (via the change in 'currentView'), is some event called for the newly (re)displayed component? If so, I could presumably call some function?
LATER: I have determined that the 'activated' hook is called when I switch to the edit-product component, which I imagine I should be able to use somehow. Now to figure that out.
You could use Vuex for that. Vuex is a Flux inspired state management library for Vue.
Your application basically has two different states: (1) no product selected (list-products component), and (2) any product selected (edit-product). When this is modeled with Vuex, the idea is to keep the currently selected product in a so-called store and let the components figure out their internal state depending on the store state. Here's an example:
Create a store to keep the application state:
const store = new Vuex.Store({
state: {
selectedProduct: null
},
getters: {
selectedProduct: state => state.selectedProduct
},
mutations: {
selectProduct: (state, data) => state.selectedProduct = data
}
});
Handle product selection in your list-products component:
methods: {
selectProduct(product) {
this.$store.commit('selectProduct', product);
}
}
Display the current product in edit-product:
Vue.component('edit-product', {
store,
template: '<div>{{selectedProduct.name}}</div>',
computed: Vuex.mapGetters(['selectedProduct'])
});
And finally switch the components depending on the state:
new Vue({
el: '#app',
store,
computed: Object.assign(Vuex.mapGetters(['selectedProduct']), {
currentView() {
return this.selectedProduct ? 'edit-product' : 'list-products'
}
})
});
Here's a basic working JSFiddle.
I'm somewhat new to Vue, and I'm having particular difficulty in passing in formData to my individual child nodes. Ideally each child node simply updates the parent formData object allowing me to submit the form data later on as a whole.
I've setup a JSFiddle to illustrate: https://jsfiddle.net/3nm1mrLo/
My current thinking is that I should v-bind:field="formData.name" but that throws an error. It seems as though formData doesn't exist in the slot based HTML.
Any pointers would be gratefully received. Thanks!
As you rightly said, you need to use v-bind:field="formData.name" or :field="formData.name".
It is not working because you have defined the main app template directly in your html, and used "content distribution" to include <example-form> and <example-input>.
As defined in the docs, this content-distribution (or "transclusion" if you are familiar with Angular 1.x) works fine, but the scope belongs to the main app (the root instance, because the template belongs to it).
Ref: https://v2.vuejs.org/v2/guide/components.html#Compilation-Scope
Quote:
A simple rule of thumb for component scope is:
Everything in the parent template is compiled in parent scope; everything in the child template is compiled in child scope.
If you are curious, try changing your main app (root instance) as follows:
new Vue({
el: '*[my-app]',
data: function() {
return {
formData: { name: 'abc', location: 'xyz'}
};
}
});
Now you will see that formData is not undefined anymore.
But a more proper method is to include <example-input> as part of the template of example-form component as follows:
Vue.component('example-form', {
template: `
<div class="my-example-form">
<form><pre>{{formData}}</pre><slot></slot></form>
<example-input :field="formData.name"></example-input>
<example-input :field="formData.location"></example-input>
</div>
`,
data: function() {
return {
formData: { name: '', location: ''}
};
}
});
Now it will bind to the right formData as you would expect.
But this will still not work for you because props is a one-way binding only. The child component (example-input) will get the value, but will not pass the data changes back to parent component (example-form)
For child to pass data back to parent, the right way is to use $emit as explained in this question: Updating parent data via child component?
If you want to have an <example-input> component to work as form elements, here is a related answer which works like what you expect: https://stackoverflow.com/a/40337942/654825 - there is a working jsFiddle also.
I'm using the vue-cli scaffold for webpack
My Vue component structure/heirarchy currently looks like the following:
App
PDF Template
Background
Dynamic Template Image
Static Template Image
Markdown
At the app level, I want a vuejs component method that can aggregate all of the child component's data into a single JSON object that can be sent off to the server.
Is there a way to access child component's data? Specifically, multiple layers deep?
If not, what is the best practice for passing down oberservable data/parameters, so that when it's modified by child components I have access to the new values? I'm trying to avoid hard dependencies between components, so as of right now, the only thing passed using component attributes are initialization values.
UPDATE:
Solid answers. Resources I found helpful after reviewing both answers:
Vuex and when to use it
Vuex alternative solution for smaller apps
In my child component, there are no buttons to emit changed data. It's a form with somewhat 5~10 inputs. the data will be submitted once you click the process button in another component. so, I can't emit every property when it's changing.
So, what I did,
In my parent component, I can access child's data from "ref"
e.g
<markdown ref="markdowndetails"></markdown>
<app-button #submit="process"></app-button>
// js
methods:{
process: function(){
// items is defined object inside data()
var markdowns = this.$refs.markdowndetails.items
}
}
Note: If you do this all over the application I suggest move to vuex instead.
For this kind of structure It's good to have some kind of Store.
VueJS provide solution for that, and It's called Vuex.If you are not ready to go with Vuex, you can create your own simple store.
Let's try with this
MarkdownStore.js
export default {
data: {
items: []
},
// Methods that you need, for e.g fetching data from server etc.
fetchData() {
// fetch logic
}
}
And now you can use those data everywhere, with importing this Store file
HomeView.vue
import MarkdownStore from '../stores/MarkdownStore'
export default {
data() {
sharedItems: MarkdownStore.data
},
created() {
MarkdownStore.fetchData()
}
}
So that's the basic flow that you could use, If you dont' want to go with Vuex.
what is the best practice for passing down oberservable data/parameters, so that when it's modified by child components I have access to the new values?
The flow of props is one way down, a child should never modify its props directly.
For a complex application, vuex is the solution, but for a simple case vuex is an overkill. Just like what #Belmin said, you can even use a plain JavaScript object for that, thanks to the reactivity system.
Another solution is using events. Vue has already implemented the EventEmitter interface, a child can use this.$emit('eventName', data) to communicate with its parent.
The parent will listen on the event like this: (#update is the shorthand of v-on:update)
<child :value="value" #update="onChildUpdate" />
and update the data in the event handler:
methods: {
onChildUpdate (newValue) {
this.value = newValue
}
}
Here is a simple example of custom events in Vue:
http://codepen.io/CodinCat/pen/ZBELjm?editors=1010
This is just parent-child communication, if a component needs to talk to its siblings, then you will need a global event bus, in Vue.js, you can just use an empty Vue instance:
const bus = new Vue()
// In component A
bus.$on('somethingUpdated', data => { ... })
// In component B
bus.$emit('somethingUpdated', newData)
you can meke ref to child component and use it as this
this.$refs.refComponentName.$data
parent-component
<template>
<section>
<childComponent ref="nameOfRef" />
</section>
</template>
methods: {
save() {
let Data = this.$refs.nameOfRef.$data;
}
},
In my case I have a registration form that I've broken down into components.
As suggested above I used $refs, In my parent I have for example:
In Template:
<Personal ref="personal" />
Script - Parent Component
export default {
components: {
Personal,
Employment
},
data() {
return {
personal: null,
education: null
}
},
mounted: function(){
this.personal = this.$refs.personal.model
this.education = this.$refs.education.model
}
}
This works well as the data is reactive.