Vue.JS not update data into nested Component - laravel

Question

I'm working with 3 VUE nested components (main, parent and child) and I'm getting trouble passing data.
The main component useget a simple API data based on input request: the result is used to get other info in other component.
For example first API return the regione "DE", the first component is populated then try to get the "recipes" from region "DE" but something goes wrong: The debug comments in console are in bad order and the variable used results empty in the second request (step3):
app.js:2878 Step_1: DE
app.js:3114 Step_3: 0
app.js:2890 Step_2: DE
This is the parent (included in main component) code:
parent template:
<template>
<div>
<recipes :region="region"/>
</div>
</template>
parent code:
data: function () {
return {
region: null,
}
},
beforeRouteEnter(to, from, next) {
getData(to.params.e_title, (err, data) => {
console.log("Step_1: "+data.region); // return Step_1: DE
// here I ned to update the region value to "DE"
next(vm => vm.setRegionData(err, data));
});
},
methods: {
setRegionData(err, data) {
if (err) {
this.error = err.toString();
} else {
console.log("Step_2: " + data.region); // return DE
this.region = data.region;
}
}
},
child template:
<template>
<div v-if="recipes" class="content">
<div class="row">
<recipe-comp v-for="(recipe, index) in recipes" :key="index" :title="recipe.title" :vote="recipe.votes">
</recipe-comp>
</div>
</div>
</template>
child code:
props: ['region'],
....
beforeMount () {
console.log("Step_3 "+this.region); // Return null!!
this.fetchData()
},
The issue should be into parent beforeRouteEnter hook I think.
Important debug notes:
1) It looks like the child code works properly because if I replace the default value in parent data to 'IT' instead of null the child component returns the correct recipes from second API request. This confirms the default data is updated too late and not when it got results from first API request.
data: function () {
return {
region: 'IT',
}
},
2) If I use {{region}} in child template it shows the correct (and updated) data: 'DE'!
I need fresh eyes to fix it. Can you help me?

Answer 1

Instead of using the beforeMount hook inside of the child component, you should be able to accomplish this using the watch property. I believe this is happening because the beforeMount hook is fired before the parent is able to set that property.
More on the Vue lifecycle can be found here
More on the beforeMount lifecycle hook can be found here
In short, you can try changing this:
props: ['region'],
....
beforeMount () {
console.log("Step_3 "+this.region); // Return null!!
this.fetchData()
},
To something like this:
props: ['region'],
....
watch: {
region() {
console.log("Step_3 "+this.region); // Return null!!
this.fetchData()
}
},
Cheers!!