You need to understand, the component hierarchy you are having and how you are passing props, definitely your case is special and not usually encountered by the devs.
Parent Component -myProp-> Child Component -myProp-> Grandchild
Component
If myProp is changed in parent component it will be reflected in the child component too.
And if myProp is changed in child component it will be reflected in grandchild component too.
So if myProp is changed in parent component then it will be reflected in grandchild component. (so far so good).
Therefore down the hierarchy you don't have to do anything props will be inherently reactive.
Now talking about going up in hierarchy
If myProp is changed in grandChild component it won't be reflected in the child component. You have to use .sync modifier in child and emit event from the grandChild component.
If myProp is changed in child component it won't be reflected in the parent component. You have to use .sync modifier in parent and emit event from the child component.
If myProp is changed in grandChild component it won't be reflected in the parent component (obviously). You have to use .sync modifier child and emit event from the grandchild component, then watch the prop in child component and emit an event on change which is being listened by parent component using .sync modifier.
Let's see some code to avoid confusion
Parent.vue
<template>
<div>
<child :myProp.sync="myProp"></child>
<input v-model="myProp"/>
<p>{{myProp}}</p>
</div>
</template>
<script>
import child from './Child.vue'
export default{
data(){
return{
myProp:"hello"
}
},
components:{
child
}
}
</script>
<style scoped>
</style>
Child.vue
<template>
<div> <grand-child :myProp.sync="myProp"></grand-child>
<p>{{myProp}}</p>
</div>
</template>
<script>
import grandChild from './Grandchild.vue'
export default{
components:{
grandChild
},
props:['myProp'],
watch:{
'myProp'(){
this.$emit('update:myProp',this.myProp)
}
}
}
</script>
<style>
</style>
Grandchild.vue
<template>
<div><p>{{myProp}}</p>
<input v-model="myProp" @input="changed"/>
</div>
</template>
<script>
export default{
props:['myProp'],
methods:{
changed(event){
this.$emit('update:myProp',this.myProp)
}
}
}
</script>
<style>
</style>
But after this you wont help notice the screaming warnings of vue saying
'Avoid mutating a prop directly since the value will be overwritten
whenever the parent component re-renders.'
Again as I mentioned earlier most of the devs don't encounter this issue, because it's an anti pattern. That's why you get this warning.
But in order to solve your issue (according to your design). I believe you have to do the above work around(hack to be honest). I still recommend you should rethink your design and make is less prone to bugs.
I hope it helps.
