Adding Pinia to a Vite + Vue 3 + TypeScript Project

Pinia is the state management library recommended for Vue 3 and maintained by the Vue core team. It is intended as a replacement for Vuex, with a smaller and more direct API.

Key characteristics:

• Simpler, more direct API, including composition-style usage.
• Module hot updates and server-side rendering support.
• Stronger TypeScript support.

Install

npm i pinia

Set up Pinia

1. Create the Pinia instance

Create a store folder under src and add an index.ts file:

import { createPinia } from 'pinia'

const store = createPinia()

export default store

2. Register it in the app

Import and use it in main.ts:

import { createApp } from 'vue'
import pinia from '@/store'
import './style.css'
import App from './App.vue'

import router from '@/router/index'

createApp(App).use(router).use(pinia).mount('#app')

3. Define a store

Create a store.ts type declaration in the types folder:

export interface UserState {
  token: string
  userInfo: { name?: string; phone?: string }
}

Create a modules folder inside store, then add user.ts:

import { defineStore } from 'pinia'
import { UserState } from 'types/store'

// first argument is the id, must be unique
export const useUserStore = defineStore('user', {
  state: () => {
    return {
      token: 'EFA68205747CB561BB7C0F85D5689856',
      userInfo: { name: 'weizwz', phone: '18392016879' }
    }
  },
  getters: {
    namePic: (state) => state.userInfo.name.substring(0, 1)
  },
  actions: {
    setToken(token: string) {
      this.token = token
    },
    setUserInfo(userInfo: UserState['userInfo']) {
      this.userInfo = { ...this.userInfo, ...userInfo }
    }
  }
})

4. Use the store in components

Update home.vue under the view folder to read from the store:

<script setup lang="ts">
import { computed } from 'vue'
import { storeToRefs } from 'pinia'
import { useUserStore } from '@store/user'

defineOptions({
  name: 'V-home'
})

const userStore = useUserStore()
// To access state reactively, use computed or storeToRefs. Accessing it directly is not reactive (you always get the initial value).
const username = computed(() => userStore.userInfo.name)
// To access getters, use storeToRefs or use them directly in the template as userStore.namePic.
const { namePic, token } = storeToRefs(userStore)
</script>

<template>
  <div>Hello: {{ namePic }}, your name is {{ username }}, your token is {{ token }}</div>
</template>

<style scoped></style>

Update login.vue under the view folder to write to the store:

<script setup lang="ts">
import { ref } from 'vue'
import { storeToRefs } from 'pinia'
import { useUserStore } from '@store/user'

defineOptions({
  name: 'V-login'
})

const userStore = useUserStore()
const { userInfo, token } = storeToRefs(userStore)
const userName = ref(userInfo.value.name)
const userToken = ref(token)

const updateUserName = () => {
  userStore.setUserInfo({
    name: userName.value
  })
}
const updateUserToken = () => {
  userStore.setToken(userToken.value)
}
</script>

<template>
  <div>login page</div>
  name:
  <input type="text" v-model="userName" @input="updateUserName" />
  <br />
  token:
  <input type="text" v-model="userToken" @input="updateUserToken" />
</template>

<style scoped></style>

If @store/user cannot be resolved, add this path to paths in tsconfig.json:

"paths": {
  "@store/*": ["src/store/modules/*"],
},

Persistence

Refreshing the page resets the store, so it is common to persist it in a cookie or in storage. For cookies, js-cookie is a practical option.

1. Install

npm i js-cookie -S
npm i @types/js-cookie -S

2. Wrap cookie helpers

Create a utils folder under src, then add auth.ts:

import Cookies from 'js-cookie'

export const TokenKey = 'weiz-token'

type ExpiresData = Date | number
export interface TokenInfo {
  token: string
  expires: ExpiresData
}

export function getToken() {
  return Cookies.get(TokenKey)
}

export function setToken(data: TokenInfo) {
  const { token, expires } = data
  return expires ? Cookies.set(TokenKey, token, { expires: expires }) : Cookies.set(TokenKey, token)
}

export function removeToken() {
  return Cookies.remove(TokenKey)
}

3. Use the cookie helpers in the store

Update user.ts under store:

import { getToken, setToken } from '@/utils/auth'
// omitted
state: () => {
  return {
    token: getToken() || 'EFA68205747',
    userInfo: { name: 'weizwz', phone: '18392016879' }
  }
}
// omitted
setToken(token: string) {
  this.token = token
  setToken({
    token,
    expires: 30
  })
}

Here’s the result in action: