Vue - requests and watch data on unmounted components - vuejs3

Question

I'm new to vue and strugling with some props and attributes.
I have a vue application where the main app is calling three different components:
Navbar,
Sidebar
MapContainer
In Navbar user will fill a selector with information about city and states. After user presses search, the list of results will then show up in the Sidebar menu.
Sidebar itself is a simple component carrying only a router-view for it's children components which are Results and Details
Results will receive the result of the search performed in the Navbar component. When user clicks any item in the Results component, Sidebar will then load Details taking the place of Results with detailed information about that place.
the problem is that the data used to make the request(city and states) comes from the first component navbar. I'm passing this data to sub-components using vue-router params option. When component Results gets unmounted, I lost all the data that was passed, even adding a Watch couldn'd fix the problem and thus can't return back to the previous page. Even adding a Watch couldn'd fix the problem. What's the proper way to handle data across components that area unmounted?
Navbar.vue
<template>
<div class="navbar">
<div class="logo">
Logo
</div>
<div class="middle">
<div class="flex-selectors">
<div class="navbar-options">
<select v-model="state_id" class="main-selectors" #click="load_cities">
<option v-for="state in states" :value="state.state_id" :key="state">
{{ state.state }}
</option>
</select>
<select v-model="city_id" class="main-selectors">
<option v-for="city in cities" :value="city.city_id" :key="city">
{{ city.city }}
</option>
</select>
</div>
<div class="search">
<button #click="seach">
<router-link :to="{name: 'results', params: {state: state_id, city: city_id} }" aria-current="page" title="Resultados">
<div>Search</div>
</router-link>
</button>
</div>
</div>
</div>
</template>
Sidebar.vue
<template>
<div class="sidebar">
<router-view></router-view>
</div>
</template>
Results.vue
<template>
<div v-if="areas.length">
<router-link :to="{name: 'details' }" tag="div" class="container" #click="load(area)" v-for="area in areas" :key="area" :value="area">
<!-- BUNCH OF DIVS AND V-FOR -->
</router-link>
</div>
<div v-else>
NA
</div>
</template>
<script>
export default {
data() {
return {
state_id: this.$route.params.state,
city_id: this.$route.params.city,
areas: [],
}
},
methods: {
search(state_id, city_id) {
load_areas.get(state_id, city_id).then(
result => {
this.areas = result.data
}
)
}
},
mounted() {
this.emitter = inject('emitter')
this.searchAreas(this.state_id, this.city_id)
},
created() {
this.$watch(
() => this.$route.params,
(toParams, previousParams) => {
this.searchAreas(toParams.state, toParams.city)
}
)
},
watch: {}
}
</script>

Answer 1

What's the proper way to handle data across components that are
unmounted?
You cannot access data from an unmounted component.
When multiple components need to access or modify the same data, a good option to look into is state management. Pinia is the new official library recommendation for state management.
Instead of passing data through vue-router params, create a store for it. Set results of your search query from Navbar component and access it in Results component. When Results component gets unmounted, you won't lose the data.