A lot of time while building your UI, you may have to switch your child components based on some value. Let's say you have a form for adding a question. You will also have a dropdown field to select the type of your question. If you select type as Multiple Choice, you may have a different set of configurations or you select Checkboxes, you may have a completely different set of configurations.
The aim is the efficiently switch between the child components and get back the data from the selected child component.
Let's build
We will be building an Add new vehicle form where Name and Type are a part of the main component.
Based on the type selected we switch the configuration form (child component) of the selected vehicle type. Finally, whatever configuration is added, should be passed back to the main form.
This is what it would look like.
The project structure is given below. We will use App.vue as the main component and Car, Motorcycle, Truck as the switchable child components.
// project structure
- src/
- components/
- Car.vue
- Motorcycle.vue
- Truck.vue
- App.vue
...
Initial setup
In the App.vue, we create data to store the name, vehicle type, and vehicle configuration.
// App.vue
// =========
<script>
export default {
name: 'App',
data() {
return {
name: '',
vehicleType: 'CAR',
vehicleConfig: {}
}
}
}
</script>
And then we bind name to the input text field and the vehicleType to the select field using v-model. At the bottom, after the hr tag, we display all the data.
// App.vue
// =========
<template>
<div id="app">
<div>
<label>Name: </label>
<input type="text" v-model="name">
</div>
<div>
<label>Type: </label>
<select v-model="vehicleType">
<option value="CAR">Car</option>
<option value="MOTORCYCLE">Motorcycle</option>
<option value="TRUCK">Truck</option>
</select>
</div>
<hr>
<div>
Vehicle type: {{ vehicleType }}
<br><br>
Vehicle name: {{ name }}
<br><br>
Vehicle Configuration: <br>
{{ vehicleConfig }}
</div>
</div>
</template>
Switching child components
Once we import all the child components, we add a computed property selectedVehicleComponent which will return the component name based on the selected vehicleType .
// App.vue
// =========
<script>
import Car from '@/components/Car.vue'
import Motorcycle from '@/components/Motorcycle.vue'
import Truck from '@/components/Truck.vue'
export default {
name: 'App',
components: {
Car,
Motorcycle,
Truck,
},
data() {
return {
name: '',
vehicleType: 'CAR',
vehicleConfig: {}
}
},
computed: {
selectedVehicleComponent() {
switch(this.vehicleType) {
case 'CAR':
return 'Car'
case 'MOTORCYCLE':
return 'Motorcycle'
case 'TRUCK':
return 'Truck'
}
return null
}
}
}
</script>
Using the <component> tag and binding the selectedVehicleComponent property to the is attribute, we create the switchable component.
// App.vue
// =========
<template>
<div id="app">
<div>
<label>Name: </label>
<input type="text" v-model="name">
</div>
<div>
<label>Type: </label>
<select v-model="vehicleType">
<option value="CAR">Car</option>
<option value="MOTORCYCLE">Motorcycle</option>
<option value="TRUCK">Truck</option>
</select>
</div>
<component
:is="selectedVehicleComponent"
/>
<hr>
<div>
Vehicle type: {{ vehicleType }}
<br><br>
Vehicle name: {{ name }}
<br><br>
Vehicle Configuration: <br>
{{ vehicleConfig }}
</div>
</div>
</template>
Now, if you change the type of the vehicle to Motorcycle, the Motorcycle component will be loaded, if you change the type to Truck, its component will be rendered, and so on.
Passing data from the child to the parent
Let's look at the Car component.
// components/Car.vue
// ==================
<template>
<div class="container">
<div>
<label>No. of airbags: </label>
<input type="text" v-model="noOfAirbags" />
</div>
<div>
<input type="checkbox" v-model="isTractionControl" />
<label>Traction Control</label>
</div>
<div>
<input type="checkbox" v-model="isABS" />
<label>ABS</label>
</div>
</div>
</template>
<script>
export default {
name: 'Car',
data() {
return {
noOfAirbags: 0,
isTractionControl: false,
isABS: false
}
},
created() {
this.emitCarConfig()
},
methods: {
emitCarConfig() {
this.$emit('on-change-car-config', {
noOfAirbags: this.noOfAirbags,
isTractionControl: this.isTractionControl,
isABS: this.isABS,
})
}
},
watch: {
noOfAirbags() { this.emitCarConfig() },
isTractionControl() { this.emitCarConfig() },
isABS() { this.emitCarConfig() }
}
}
</script>
- The data has 3 values:
noOfAirbags, isTractionControl and isABS. We have bound these values to their corresponding input fields using v-model.
- We create a method
emitCarConfig() that emits an event with the event name on-change-car-config and passes the data as a payload.
- We call
emitCarConfig() in the created method so whenever the component is switched we pass the data to the parent.
- We create watchers to watch all the values of the data, so whenever they change we call
emitCarConfig() and pass the data to the parent.
That's it for the child component.
Now, the parent has to listen to this event on-change-car-config.
// App.vue
// =========
<template>
<div id="app">
...
<component
:is="selectedVehicleComponent"
@on-change-car-config="onChangeCarConfig"
/>
...
</div>
</template>
<script>
...
export default {
...
methods: {
onChangeCarConfig(carConfig) {
this.vehicleConfig = carConfig
}
}
}
</script>
When on-change-car-config event is fired, we call the onChangeCarConfig() method where we save the new carConfig (passed from the car component) to vehicleConfig in our parent.
Similarly, we can create Motorcycle.vue and Truck.vue, and listen to its events.
<template>
<div id="app">
...
<component
:is="selectedVehicleComponent"
@on-change-car-config="onChangeCarConfig"
@on-change-motorcycle-config="onChangeMotorcycleConfig"
@on-change-truck-config="onChangeTruckConfig"
/>
...
</div>
</template>
Finally, App.vue should look like this.
// App.vue
// =========
<template>
<div id="app">
<div>
<label>Name: </label>
<input type="text" v-model="name">
</div>
<div>
<label>Type: </label>
<select v-model="vehicleType">
<option value="CAR">Car</option>
<option value="MOTORCYCLE">Motorcycle</option>
<option value="TRUCK">Truck</option>
</select>
</div>
<div>
<component
:is="selectedVehicleComponent"
@on-change-car-config="onChangeCarConfig"
@on-change-motorcycle-config="onChangeMotorcycleConfig"
@on-change-truck-config="onChangeTruckConfig"
/>
</div>
<hr>
<div>
Vehicle type: {{ vehicleType }}
<br><br>
Vehicle name: {{ name }}
<br><br>
Vehicle Configuration: <br>
{{ vehicleConfig }}
</div>
</div>
</template>
<script>
import Car from '@/components/Car.vue'
import Motorcycle from '@/components/Motorcycle.vue'
import Truck from '@/components/Truck.vue'
export default {
name: 'App',
components: {
Car,
Motorcycle,
Truck,
},
data() {
return {
name: '',
vehicleType: 'CAR',
vehicleConfig: {}
}
},
computed: {
selectedVehicleComponent() {
switch(this.vehicleType) {
case 'CAR':
return 'Car'
case 'MOTORCYCLE':
return 'Motorcycle'
case 'TRUCK':
return 'Truck'
}
return null
}
},
methods: {
onChangeCarConfig(carConfig) {
this.vehicleConfig = carConfig
},
onChangeMotorcycleConfig(motorcycleConfig) {
this.vehicleConfig = motorcycleConfig
},
onChangeTruckConfig(truckConfig) {
this.vehicleConfig = truckConfig
}
}
}
</script>
That's it, we have successfully wired everything up. Click here to check out the full code
Thanks for reading!
