ComboBox template component with VueJS - vue.js

I want to make a Combobox template Component with vuejs v3 and to do so I have the following code:
<template>
<select name={{selector_name}} class= "combobox" id={{selector_id}}>
v-for=opt in {{selector_options}}
<option value=opt>
opt
</option>
</select>
</template>
<script>
export default {
name: 'ComboBox',
data() {
return {
selector_name: null,
selector_id: null,
selector_options : null,
}
},
props: {
selector_name: {
type: String,
required: true
},
selector_id: {
type: String,
default: "combobox"
},
selector_options: {
type: Array,
required: true
}
},
methods: {
onChange: (event) => {
console.log(event.target.value);
},
},
computed: {},
}
</script>
But the way that I use v-for does not seem to be correct to me, can you please tell me how can I correct that? thanks in advance.

I see a lot of things, to be clear and answer your questions, v-for is used on a element.
<template>
// For mor readability i recommend you do bind your property:
// - name={{selector_name}} become :name="selector_name"
<select :name="selector_name" class= "combobox" :id="selector_id">
<!-- v-for is required with a unique key, you can take the index and use it -->
<option v-for="(opt, index) in selector_options" :key="`opt ${index}`" value=opt>
{{ opt }}
</option>
</select>
</template>
You can't define a props and data with the same name. Props, inject inside a data the property and value.
It's exactly the same, but the data come from a parent where you pass a value to the child.
So use props if you need to pass data, but not define it too inside data.
There is a work example of all of that (i use data and not props for readability).

Related

Why do I have en error "Unexpected mutation of "modelValue" prop" in Vue?

So i'm working with you and I have a select component, I created a modelValue prop which is an empty string, and passed it in v-model:
<select v-model="modelValue" #change="changeOption">
<option
disabled
value="">
Choose from the list
</option>
<option
v-for="option in options"
:key="option.value"
:value="option.value">
{{ option.name }}
</option>
</select>
props:{
modelValue:{
type: String
},
options:{
type: Array,
default: () => []
}
}
But for some reason it gives an error: Unexpected mutation of "modelValue" prop.
I just started working with Vue so I'm not sure where this error could come from. I was following a tutorial and everything seemed to work there.
You can't modify a prop directly.
The best way is create a computed with get set functions and emit update inside set function.
https://v2.vuejs.org/v2/guide/computed.html#Computed-Setter
computed: {
localModelValue: {
get() {
return this.modelValue
},
set(newValue) {
this.$emit('update:modelValue', newValue)
},
},
},
And in the component instance declare prop as sync
https://v2.vuejs.org/v2/guide/components-custom-events.html#sync-Modifier
:model-value.sync="..."
create life cycle "computed"
computed: {
localModelValue: {
get() {
return this.modelValue
},
},
},
After that change v-model="modelValue" to v-model="localModelValue"

vue.js - passing selected option string data from <childComponent1/> to <childComponent2/>

I have this block of code in <oneChildComponent />, based on <select> element:
new Vue({
template:'
<select v-model="selectedOption" #change="handleChange">
<option value="" disabled>--Select--</option>
<option v-for="item in data" :value="item.val">
{{item.text}}
</option>
</select>
',
data:{
selectedOption:''
},
methods:{
handleChange:function(event){
console.log(this.selectedOption); //you will find the value here
}
}
})
The goal is to take a string value of selectedOption and pass it from <oneChildComponent /> to <anotherChildComponent />. Those components are contained in main parent component.
Is it possible to modify this handleChange() method with $emit(), and what's the best way to do it?
I'me new with vue.js, so thanks in advance.
Simply emit the changed value to the parent:
handleChange: function(event){
this.$emit("valueChanged", this.selectedOption);
}
In the parent, you need to define a variable, in which the emitted value is stored, and a function for assigning it.
{
data: function() {
return {
myValue: ""
}
},
methods: {
setValue(value) {
this.myValue = value;
}
}
}
Also in the parent, you then can intercept this emit and set this value by doing:
<oneChildComponent #valueChanged="setValue"/>
Finally, you have to pass myValue to your second child component as prop:
<anotherChildComponent :myValue="myValue" />
This variable is available in this child component by declaring it as a prop:
{
props: {
myValue: String
}
}

Vue.js custom component with HTML <select> and v-model (W3C compliant)

I'm new to Vue.js (using Nuxt.js) and what I'm trying to achieve is to have a Select component that I can reuse everywhere and is W3C compliant.
With the help of #Jasmonate answers, I managed to create this component, it's working. But the value attribute is still visible in the source code and so isn't W3C compliant. Maybe the problem is coming from somewhere else in the project ?!
Parent component
<custom-select
:options="options"
v-model="selectedOption"
></custom-select>
<span>Selected : {{ selectedOption }}</span>
<script>
data() {
return {
selectedOption: "A",
options: [
{ label: "One", value: "A" },
{ label: "Two", value: "B" },
{ label: "Three", value: "C" }
],
};
}
</script>
custom-select.vue
<template>
<select :value="value" #input="clicked">
<option
v-for="option in options"
:key="option.label"
:value="option.value"
>
{{ option.label }}
</option>
</select>
</template>
<script>
export default {
props: {
value: {
required: true
},
options: {
type: Array,
required: true
}
},
methods: {
clicked($event) {
this.$emit("input", $event.target.value);
}
}
};
</script>
I read those documentation pages:
Form Input Bindings
Components Basics
And also looked around the web to find example of v-model in a custom component, but it's always about the input tag. The only example I found about a custom select with v-model isn't actually a select tag, like the Vue Select plugin or this thread on StackOverflow.
v-model is syntax sugar. By default, the value is a prop that has the name value, and it changes (two-way-binding) whenever the event input is emitted.
Also, v-model is bound on the select element, not option.
Your code can be modified as such:
<template>
<select :value="value" #input="clicked">
<option
v-for="option in options"
:key="option.label"
:value="option.value"
>
{{ option.label }}
</option>
</select>
</template>
<script>
export default {
props: {
value: {
required: true
},
options: {
type: Array,
required: true
}
},
methods: {
clicked($event) {
this.$emit('input', $event.target.value);
}
}
};
</script>
Documentation here: https://v2.vuejs.org/v2/guide/components.html#Using-v-model-on-Components
You can also change the prop name and event name that v-model uses, see: https://v2.vuejs.org/v2/guide/components-custom-events.html#Customizing-Component-v-model

Conditional <router-link> in Vue.js dependant on prop value?

Hopefully this is a rather simple question / answer, but I can't find much info in the docs.
Is there a way to enable or disable the anchor generated by <router-link> dependent on whether a prop is passed in or not?
<router-link class="Card__link" :to="{ name: 'Property', params: { id: id }}">
<h1 class="Card__title">{{ title }}</h1>
<p class="Card__description">{{ description }}</p>
</router-link>
If there's no id passed to this component, I'd like to disable any link being generated.
Is there a way to do this without doubling up the content into a v-if?
Thanks!
Assuming you want to disable anchor tag as in not clickable and look disabled the option is using CSS. isActive should return true by checking prop id.
<router-link class="Card__link" v-bind:class="{ disabled: isActive }" :to="{ name: 'Property', params: { id: id }}">
<h1 class="Card__title">{{ title }}</h1>
<p class="Card__description">{{ description }}</p>
</router-link>
<style>
.disabled {
pointer-events:none;
opacity:0.6;
}
<style>
If you want to just disable the navigation , you can use a route guard.
beforeEnter: (to, from, next) => {
next(false);
}
If you need to use it often, consider this:
Create new component
<template>
<router-link
v-if="!disabled"
v-bind="$attrs"
>
<slot/>
</router-link>
<span
v-else
v-bind="$attrs"
>
<slot/>
</span>
</template>
<script>
export default {
name: 'optional-router-link',
props: {
params: Object,
disabled: {
type: Boolean,
default: false,
},
},
};
</script>
Optional, register globally:
Vue.component('optional-router-link', OptionalRouterLink);
Use it as follows:
<optional-router-link
:disabled="isDisabled"
:to="whatever"
>
My link
</optional-router-link>
The problem is that router-link renders as an html anchor tag, and anchor tags do not support the disabled attribute. However you can add tag="button" to router-link:
<router-link :to="myLink" tag="button" :disabled="isDisabled" >
Vue will then render your link as a button, which naturally supports the disabled attribute. Problem solved! The downside is that you have to provide additional styling to make it look like a link. However this is the best way to achieve this functionality and does not rely on any pointer-events hack.
I sometimes do stuff like this:
<component
:is="hasSubLinks ? 'button' : 'router-link'"
:to="hasSubLinks ? undefined : href"
:some-prop="computedValue"
#click="hasSubLinks ? handleClick() : navigate"
>
<!-- arbitrary markup -->
</component>
...
computed: {
computedValue() {
if (this.hasSubLinks) return 'something';
if (this.day === 'Friday') return 'tgif';
return 'its-fine';
},
},
But I basically always wrap router-link, so you can gain control over disabled state, or pre-examine any state or props before rendering the link, with something like this:
<template>
<router-link
v-slot="{ href, route, navigate, isActive, isExactActive }"
:to="to"
>
<a
:class="['nav-link-white', {
'nav-link-white-active': isActive,
'opacity-50': isDisabled,
}]"
:href="isDisabled ? undefined : href"
#click="handler => handleClick(handler, navigate)"
>
<slot></slot>
</a>
</router-link>
</template>
<script>
export default {
name: 'top-nav-link',
props: {
isDisabled: {
type: Boolean,
required: false,
default: () => false,
},
to: {
type: Object,
required: true,
},
},
data() {
return {};
},
computed: {},
methods: {
handleClick(handler, navigate) {
if (this.isDisabled) return undefined;
return navigate(handler);
},
},
};
</script>
In my app right now, I'm noticing that some combinations of #click="handler => handleClick(handler, navigate)" suffer significantly in performance.
For example this changes routes very slow:
#click="isDisabled ? undefined : handler => navigate(handler)"
But the pattern in my full example code above works and has no performance issue.
In general, ternary operator in #click can be very dicey, so if you get issues, don't give up right away, try many different ways to bifurcate on predicates or switch over <component :is="" based on state. navigate itself is an ornery one because it requires the implicit first parameter to work.
I haven't tried, but you should be able to use something like Function.prototype.call(), Function.prototype.apply(), or Function.prototype.bind().
For example, you might be able to do:
#click="handler => setupNavigationTarget(handler, navigate)"
...
setupNavigationTarget(handler, cb) {
if (this.isDisabled) return undefined;
return this.$root.$emit('some-event', cb.bind(this, handler));
},
...
// another component
mounted() {
this.$root.$on('some-event', (navigate) => {
if (['Saturday', 'Sunday'].includes(currentDayOfTheWeek)) {
// halt the navigation event
return undefined;
}
// otherwise continue (and notice how downstream logic
// no longer has to care about the bound handler object)
return navigate();
});
},
You could also use the following:
<router-link class="Card__link" :to="id ? { name: 'Property', params: { id: id }} : {}">
<h1 class="Card__title">{{ title }}</h1>
<p class="Card__description">{{ description }}</p>
</router-link>
If id is undefined the router won't redirect the page to the link.
I've tried different solutions but only one worked for me, maybe because I'm running if from Nuxt? Although theoretically nuxt-link should work exactly the same as router-link.
Anyway, here is the solution:
<template>
<router-link
v-slot="{ navigate }"
custom
:to="to"
>
<button
role="link"
#click="onNavigation(navigate, $event)"
>
<slot></slot>
</button>
</router-link>
</template>
<script>
export default {
name: 'componentName',
props: {
to: {
type: String,
required: true,
},
},
methods: {
onNavigation(navigate, event) {
if (this.to === '#other-action') {
// do something
} else {
navigate(event);
}
return false;
},
};
</script>

VueJs reactivity with parent component property object

I'm having difficulty to get parent component's property object, with dynamically populated properties to make the values available inside of the same component.
A bit hard to explain, so please have a look at the example below:
Parent Component
<script>
export default {
data() {
return {
fields: {},
}
}
}
</script>
Child Component
<template>
<select
#change="update()"
v-model="field"
>
<option
v-for="option in options"
:value="option.value"
>
{{ option.name }}
</option>
</select>
</template>
<script>
export default {
props: {
initialOptions: {
type: Array,
required: true
}
},
data() {
return {
field: '',
options: this.initialOptions
}
},
mounted() {
if (
(this.field === undefined || this.field === '') &&
this.options.length > 0
) {
this.field = this.options[0].value;
}
this.update();
},
methods: {
update() {
this.$emit('input', this.field);
}
}
}
</script>
DOM
<parent-component inline-template>
<div>
<child-component>
:initial-options="[{..}, {..}]"
v-model="fields.type_id"
></child-component>
</div>
<div :class="{ dn : fields.type_id == 2 }">
// ...
</div>
</parent-component>
Using Vue console I can see that fields object gets all of the child component models with their associated values as they emit input when they are mounted, however for some strange reason the :class="{ dn : fields.type_id == 2 }" does not append the class dn when the selection changes to 2. Dom doesn't seem to reflect the changes that are synced between parent and child components.
Any help on how to make it work?
Here is what I was trying to get at in comments. Vue cannot detect changes to properties that are added dynamically to an object unless you add them using $set. Your fields object does not have a type_id property, but it gets added because you are using v-model="fields.type_id". As such, Vue does not know when it changes.
Here, I have added it and the color of the text changes as you would expect.
console.clear()
Vue.component("child-component", {
template: `
<select
#change="update()"
v-model="field"
>
<option
v-for="option in options"
:value="option.value"
>
{{ option.name }}
</option>
</select>
`,
props: {
initialOptions: {
type: Array,
required: true
}
},
data() {
return {
field: '',
options: this.initialOptions
}
},
mounted() {
if (
(this.field === undefined || this.field === '') &&
this.options.length > 0
) {
this.field = this.options[0].value;
}
this.update();
},
methods: {
update() {
this.$emit('input', this.field);
}
}
})
new Vue({
el: "#app",
data: {
fields: {
type_id: null
}
}
})
.dn {
color: red;
}
<script src="https://unpkg.com/vue#2.2.6/dist/vue.js"></script>
<div id="app">
<div>
<child-component :initial-options="[{name: 'test', value: 1}, {name: 'test2', value: 2}]" v-model="fields.type_id"></child-component>
</div>
<div :class="{ dn : fields.type_id == 2 }">
Stuff
</div>
</div>
It looks like you are trying to make a re-usable component.
I would ask myself what the value of a re-usable component is when the parent component has to handle more than half of the effort. The component might be better named...
<DifficultToUseSelect/>.
Essentially, you are creating a component that provides, all by itself, all of the following HTML...
<select></select>
Everything else is managed by the parent component.
It would probably be more useful to do any of the following...
Encapsulate often needed options in a specific select component, as in
StateAbbrevsSelect v-model="state"
Pass the name of a data model to a select component. The component would then load and manage its own data via the model.
Pass the URL of a web service to the component, which it then calls to load its options.
Again, the main point I am trying to convey here is that making a re-usable component where more than half of the effort is handled by the parent component is really not very re-usable.