Plugins

Pinia stores can be fully extended thanks to a low level API. Here is a list of things you can do:

• Add new properties to stores
• Add new options when defining stores
• Add new methods to stores
• Wrap existing methods
• Intercept actions and its results
• Implement side effects like Local Storage
• Apply only to specific stores

Plugins are added to the pinia instance with pinia.use(). The simplest example is adding a static property to all stores by returning an object:

import { createPinia } from 'pinia'

// add a property named `secret` to every store that is created
// after this plugin is installed this could be in a different file
function SecretPiniaPlugin() {
  return { secret: 'the cake is a lie' }
}

const pinia = createPinia()
// give the plugin to pinia
pinia.use(SecretPiniaPlugin)

// in another file
const store = useStore()
store.secret // 'the cake is a lie'

This is useful to add global objects like the router, modal, or toast managers.

Introduction

A Pinia plugin is a function that optionally returns properties to be added to a store. It takes one optional argument, a context:

export function myPiniaPlugin(context) {
  context.pinia // the pinia created with `createPinia()`
  context.app // the current app created with `createApp()` (Vue 3 only)
  context.store // the store the plugin is augmenting
  context.options // the options object defining the store passed to `defineStore()`
  // ...
}

This function is then passed to pinia with pinia.use():

pinia.use(myPiniaPlugin)

Plugins are only applied to stores created after the plugins themselves, and after pinia is passed to the app, otherwise they won't be applied.

Augmenting a Store

You can add properties to every store by simply returning an object of them in a plugin:

pinia.use(() => ({ hello: 'world' }))

You can also set the property directly on the store but if possible use the return version so they can be automatically tracked by devtools:

pinia.use(({ store }) => {
  store.hello = 'world'
})

Any property returned by a plugin will be automatically tracked by devtools so in order to make hello visible in devtools, make sure to add it to store._customProperties in dev mode only if you want to debug it in devtools:

// from the example above
pinia.use(({ store }) => {
  store.hello = 'world'
  // make sure your bundler handle this. webpack and vite should do it by default
  if (process.env.NODE_ENV === 'development') {
    // add any keys you set on the store
    store._customProperties.add('hello')
  }
})

Note that every store is wrapped with reactive, automatically unwrapping any Ref (ref(), computed(), ...) it contains:

const sharedRef = ref('shared')
pinia.use(({ store }) => {
  // each store has its individual `hello` property
  store.hello = ref('secret')
  // it gets automatically unwrapped
  store.hello // 'secret'

  // all stores are sharing the value `shared` property
  store.shared = sharedRef
  store.shared // 'shared'
})

This is why you can access all computed properties without .value and why they are reactive.

Adding new state

If you want to add new state properties to a store or properties that are meant to be used during hydration, you will have to add it in two places:

• On the store so you can access it with store.myState
• On store.$state so it can be used in devtools and, be serialized during SSR.

On top of that, you will certainly have to use a ref() (or other reactive API) in order to share the value across different accesses:

import { toRef, ref } from 'vue'

pinia.use(({ store }) => {
  // to correctly handle SSR, we need to make sure we are not overriding an
  // existing value
  if (!store.$state.hasOwnProperty('hasError')) {
    // hasError is defined within the plugin, so each store has their individual
    // state property
    const hasError = ref(false)
    // setting the variable on `$state`, allows it be serialized during SSR
    store.$state.hasError = hasError
  }
  // we need to transfer the ref from the state to the store, this way
  // both accesses: store.hasError and store.$state.hasError will work
  // and share the same variable
  // See https://vuejs.org/api/reactivity-utilities.html#toref
  store.hasError = toRef(store.$state, 'hasError')

  // in this case it's better not to return `hasError` since it
  // will be displayed in the `state` section in the devtools
  // anyway and if we return it, devtools will display it twice.
})

Note that state changes or additions that occur within a plugin (that includes calling store.$patch()) happen before the store is active and therefore do not trigger any subscriptions.

WARNING

If you are using Vue 2, Pinia is subject to the same reactivity caveats as Vue. You will need to use Vue.set() (Vue 2.7) or set() (from @vue/composition-api for Vue <2.7) for when creating new state properties like secret and hasError:

import { set, toRef } from '@vue/composition-api'
pinia.use(({ store }) => {
  if (!store.$state.hasOwnProperty('secret')) {
    const secretRef = ref('secret')
    // If the data is meant to be used during SSR, you should
    // set it on the `$state` property so it is serialized and
    // picked up during hydration
    set(store.$state, 'secret', secretRef)
  }
  // set it directly on the store too so you can access it
  // both ways: `store.$state.secret` / `store.secret`
  set(store, 'secret', toRef(store.$state, 'secret'))
  store.secret // 'secret'
})

Resetting state added in plugins

By default, $reset() will not reset state added by plugins but you can override it to also reset the state you add:

import { toRef, ref } from 'vue'

pinia.use(({ store }) => {
  // this is the same code as above for reference
  if (!store.$state.hasOwnProperty('hasError')) {
    const hasError = ref(false)
    store.$state.hasError = hasError
  }
  store.hasError = toRef(store.$state, 'hasError')

  // make sure to set the context (`this`) to the store
  const originalReset = store.$reset.bind(store)

  // override the $reset function
  return {
    $reset() {
      originalReset()
      store.hasError = false
    },
  }
})

Adding new external properties

When adding external properties, class instances that come from other libraries, or simply things that are not reactive, you should wrap the object with markRaw() before passing it to pinia. Here is an example adding the router to every store:

import { markRaw } from 'vue'
// adapt this based on where your router is
import { router } from './router'

pinia.use(({ store }) => {
  store.router = markRaw(router)
})

Calling $subscribe inside plugins

You can use store.$subscribe and store.$onAction inside plugins too:

pinia.use(({ store }) => {
  store.$subscribe(() => {
    // react to store changes
  })
  store.$onAction(() => {
    // react to store actions
  })
})

Adding new options

It is possible to create new options when defining stores to later on consume them from plugins. For example, you could create a debounce option that allows you to debounce any action:

defineStore('search', {
  actions: {
    searchContacts() {
      // ...
    },
  },

  // this will be read by a plugin later on
  debounce: {
    // debounce the action searchContacts by 300ms
    searchContacts: 300,
  },
})

The plugin can then read that option to wrap actions and replace the original ones:

// use any debounce library
import debounce from 'lodash/debounce'

pinia.use(({ options, store }) => {
  if (options.debounce) {
    // we are overriding the actions with new ones
    return Object.keys(options.debounce).reduce((debouncedActions, action) => {
      debouncedActions[action] = debounce(
        store[action],
        options.debounce[action]
      )
      return debouncedActions
    }, {})
  }
})

Note that custom options are passed as the 3rd argument when using the setup syntax:

defineStore(
  'search',
  () => {
    // ...
  },
  {
    // this will be read by a plugin later on
    debounce: {
      // debounce the action searchContacts by 300ms
      searchContacts: 300,
    },
  }
)

TypeScript

Everything shown above can be done with typing support, so you don't ever need to use any or @ts-ignore.

Typing plugins

A Pinia plugin can be typed as follows:

import { PiniaPluginContext } from 'pinia'

export function myPiniaPlugin(context: PiniaPluginContext) {
  // ...
}

Typing new store properties

When adding new properties to stores, you should also extend the PiniaCustomProperties interface.

import 'pinia'
import type { Router } from 'vue-router'

declare module 'pinia' {
  export interface PiniaCustomProperties {
    // by using a setter we can allow both strings and refs
    set hello(value: string | Ref<string>)
    get hello(): string

    // you can define simpler values too
    simpleNumber: number

    // type the router added by the plugin above (#adding-new-external-properties)
    router: Router
  }
}

It can then be written and read safely:

pinia.use(({ store }) => {
  store.hello = 'Hola'
  store.hello = ref('Hola')

  store.simpleNumber = Math.random()
  // @ts-expect-error: we haven't typed this correctly
  store.simpleNumber = ref(Math.random())
})

PiniaCustomProperties is a generic type that allows you to reference properties of a store. Imagine the following example where we copy over the initial options as $options (this would only work for option stores):

pinia.use(({ options }) => ({ $options: options }))

We can properly type this by using the 4 generic types of PiniaCustomProperties:

import 'pinia'

declare module 'pinia' {
  export interface PiniaCustomProperties<Id, S, G, A> {
    $options: {
      id: Id
      state?: () => S
      getters?: G
      actions?: A
    }
  }
}

TIP

When extending types in generics, they must be named exactly as in the source code. Id cannot be named id or I, and S cannot be named State. Here is what every letter stands for:

• S: State
• G: Getters
• A: Actions
• SS: Setup Store / Store

Typing new state

When adding new state properties (to both, the store and store.$state), you need to add the type to PiniaCustomStateProperties instead. Differently from PiniaCustomProperties, it only receives the State generic:

import 'pinia'

declare module 'pinia' {
  export interface PiniaCustomStateProperties<S> {
    hello: string
  }
}

Typing new creation options

When creating new options for defineStore(), you should extend the DefineStoreOptionsBase. Differently from PiniaCustomProperties, it only exposes two generics: the State and the Store type, allowing you to limit what can be defined. For example, you can use the names of the actions:

import 'pinia'

declare module 'pinia' {
  export interface DefineStoreOptionsBase<S, Store> {
    // allow defining a number of ms for any of the actions
    debounce?: Partial<Record<keyof StoreActions<Store>, number>>
  }
}

TIP

There is also a StoreGetters type to extract the getters from a Store type. You can also extend the options of setup stores or option stores only by extending the types DefineStoreOptions and DefineSetupStoreOptions respectively.

Nuxt.jss

You will have to create a Nuxt plugin first. This will give you access to the pinia instance:

// plugins/myPiniaPlugin.ts
import { PiniaPluginContext } from 'pinia'

function MyPiniaPlugin({ store }: PiniaPluginContext) {
  store.$subscribe((mutation) => {
    // react to store changes
    console.log(`[🍍 ${mutation.storeId}]: ${mutation.type}.`)
  })

  // Note this has to be typed if you are using TS
  return { creationTime: new Date() }
}

export default defineNuxtPlugin(({ $pinia }) => {
  $pinia.use(MyPiniaPlugin)
})

INFO

The above example is using TypeScript, you have to remove the type annotations PiniaPluginContext and Plugin as well as their imports if you are using a .js file.

Nuxt.js 2

If you are using Nuxt.js 2, the types are slightly different:

// plugins/myPiniaPlugin.ts
import { PiniaPluginContext } from 'pinia'
import { Plugin } from '@nuxt/types'

function MyPiniaPlugin({ store }: PiniaPluginContext) {
  store.$subscribe((mutation) => {
    // react to store changes
    console.log(`[🍍 ${mutation.storeId}]: ${mutation.type}.`)
  })

  // Note this has to be typed if you are using TS
  return { creationTime: new Date() }
}

const myPlugin: Plugin = ({ $pinia }) => {
  $pinia.use(MyPiniaPlugin)
}

export default myPlugin