Pinia is now the recommended choice by Vue and is now an official part of the whole Vue ecosystem, maintained and developed by core members of the Vue team
Creating a new project
npx nuxi init nuxt3-pinia
Install pinia
npm i @pinia/nuxt pinia -D
add module to nuxt.config.ts
export default defineNuxtConfig({
modules: [
// ...
'@pinia/nuxt',
],
});
Creating a todo store
create store folder in root of project, then create a todos.ts file, we will be calling https://jsonplaceholder.typicode.com/todos this is a mock API which returns a list of todos
Before diving into core concepts, we need to know that a store is defined using defineStore() and that it requires a unique name, passed as the first argument:
store/todos.ts
import { defineStore } from 'pinia';
export const useTodosStore = defineStore('todos', {
});
In Pinia the state is defined as a function that returns the initial state. This allows Pinia to work in both Server and Client Side.
let's create an empty todos state
store/todos.ts
state: () => ({
todos: [],
}),
Now lets create an action, which will call the endpoint above to fetch a list of todos and assign the data to the todos state
Actions are the equivalent of methods in components. They can be defined with the actions property in defineStore() and they are perfect to define business logic:
store/todos.ts
async fetchTodos() {
const { data } = await useFetch('https://jsonplaceholder.typicode.com/todos');
if (data.value) {
this.todos = data.value;
}
}
Nuxt 3 provides new composable called useFetch this will let us do a GET call without having to install axios
the completed code now for store/todos.ts
import { defineStore } from 'pinia';
export const useTodosStore = defineStore('todos', {
state: () => ({
todos: [],
}),
actions: {
async fetchTodos() {
const { data }: any = await useFetch('https://jsonplaceholder.typicode.com/todos');
if (data.value) {
this.todos = data.value;
}
},
},
});
How to use the todos store
open app.vue we now need to import our fetchTodos function from the store
import { useTodosStore } from '~/store/todos';
now we need to destructure our store and call the actions, states we need, destructuring the store will break reactivity.
const { fetchTodos, todos } = useTodosStore();
to maintain the reactivity we can use a computed property or storeToRefs()
Reactivity with computed
use computed property to make todos state reactive
const store = useTodosStore();
const todos = computed(() => store.todos)
Reactivity with storeToRefs()
storeToRefs() lets us destructure the store value while keeping it reactive
import { storeToRefs } from 'pinia'
const store = useTodosStore();
const { todos,} = storeToRefs(store)
what about functions
storeToRefs doesn't allow us to destructure a function we can simply call an action with store.fetchTodos or we can destructrutre the store value
import { storeToRefs } from 'pinia'
const store = useTodosStore();
const { fetchTodos } = store; // have all non reactiave stuff here
const { todos } = storeToRefs(store) // have all reactive states here
because Nuxt 3 supports top level async/await we can just call fetchTodos action
await fetchTodos();
now on our html can we loop over the todos and display each one
<template>
<div>
<h1>Todos:</h1>
<ul v-for="todo in todos" :key="todo.id">
<li>{{ todo.title }}</li>
</ul>
</div>
</template>
now we should see a list of todos
complete code for app.vue
<template>
<div>
<h1>Todos:</h1>
<ul v-for="todo in todos" :key="todo.id">
<li>{{ todo.title }}</li>
</ul>
</div>
</template>
<script lang="ts" setup>
import { storeToRefs } from 'pinia';
import { useTodosStore } from '~/store/todos';
const store = useTodosStore();
const { fetchTodos } = store; // have all non reactiave stuff here
const { todos } = storeToRefs(store); // have all reactive states here
await fetchTodos();
</script>
Alternative away of setting up pinia store
import { defineStore } from 'pinia';
export const useTodosStore = defineStore('todos', () => {
const todos = ref([]); // ref by defaults are states,
// functions get added to actions
const fetchTodos = async () => {
const { data }: any = await useFetch('https://jsonplaceholder.typicode.com/todos');
if (data.value) {
todos.value = data.value;
}
};
// we must return what we want to use accross the application
return {
todos,
fetchTodos,
};
});
This way of setting up the store feels very familiar way of creating a composbale in vue
You can find the repository here
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