How do I use vuex store in the router in Vue 3 SSR app?

Question

I have a Vue3 project with SSR, Vue-Cli, Vuex and Typescript.

In the router page I need to commit data to the Vuex Store. In a .vue file I simply use this.$store which is typed in vuex.d.ts, like:

this.$store.commit("setFoo", "Bar")

But how do I do that from a ts file (router/index.ts) where there is no this or vue instance.

I've tried importing the store index file and committing:

import store from "@/store/index"

store.commit("setFoo", "Bar")

But I get an error

Property 'commit' does not exist on type '() => Store<{ foo: string; }>'.ts(2339)

The store file (since I'm running SSR the store cant be a singleton):

import Vuex from "vuex"

export default function () {
  return new Vuex.Store({
    state: () => ({
      foo: "foo",
    }),
    mutations: {
      setFoo(state, payload) {
        state.foo = payload
      },
    },
  })
}

Updated store file for vuex 4:

import { createStore } from "vuex"

const store = {
  state: () => ({
    foo: "foo",
  })
}

export default function () {
  return createStore(store)
}

entry-client.js:

import createApp from "./main"

const { app, router } = createApp()

router.isReady().then(() => {
  app.mount("#app", true)
})

entry-server.ts:

import createApp from "./main"

export default function () {
  const { app, router } = createApp()

  return {
    app,
    router,
  }
}

main.js:

import { createSSRApp, createApp, h } from "vue"
import { isSSR } from "@/helpers"
import createRouter from "@/router"
import createStore from "@/store"
import axios from "axios"
import VueAxios from "vue-axios"
import App from "@/App.vue"

export default function () {

  const rootComponent = {
    render: () => h(App),
    components: { App },
  }

  const app = (isSSR() ? createSSRApp : createApp)(rootComponent)
  const router = createRouter()
  const store = createStore()

  app.use(VueAxios, axios)
  app.use(router)
  app.use(store)

  app.provide("axios", app.config.globalProperties.axios)

  return {
    app,
    router,
    store,
  }
}

Router/index.ts:

  import { createRouter, createWebHistory, createMemoryHistory } from "vue-router"
  import store from "@/store/index"
  import axios from "axios"
  import MockAdapter from "axios-mock-adapter"
  import { routes } from "./routes"
  import { isSSR } from "@/helpers"

  const history = isSSR()
    ? createMemoryHistory()
    : createWebHistory(process.env.BASE_URL)

  const router = createRouter({ routes, history })

  router.beforeEach(async (to, from, next) => {
   // do stuff with store
  })
  
  export default function () {
    return router
  }

Package.json:

  "scripts": {
    "build:all": "npm run build:client && npm run build:server",
    "build:client": "vue-cli-service build --dest dist/client",
    "build:server": "export SSR=1 || set SSR=1&& vue-cli-service build --dest dist/server",
    "build:server:dev": "export SSR=1 || set SSR=1&& vue-cli-service build --mode development --dest dist/server",
    "serve:client": "vue-cli-service serve",
    "serve:server": "node ./dist/server/server.js",
    "lint": "vue-cli-service lint"
  },
  "dependencies": {
    "@vue/server-renderer": "^3.2.4",
    "axios": "^0.21.1",
    "core-js": "^3.6.5",
    "express": "^4.17.1",
    "vue": "^3.0.0",
    "vue-axios": "^3.2.5",
    "vue-router": "^4.0.0-0",
    "vuex": "^4.0.0-0"
  },
  "devDependencies": {
    "@typescript-eslint/eslint-plugin": "^4.18.0",
    "@typescript-eslint/parser": "^4.18.0",
    "@vue/cli-plugin-babel": "^5.0.0-beta.3",
    "@vue/cli-plugin-eslint": "^5.0.0-beta.3",
    "@vue/cli-plugin-router": "^5.0.0-beta.3",
    "@vue/cli-plugin-typescript": "^5.0.0-beta.3",
    "@vue/cli-plugin-vuex": "^5.0.0-beta.3",
    "@vue/cli-service": "^5.0.0-beta.3",
    "@vue/compiler-sfc": "^3.0.0",
    "@vue/eslint-config-prettier": "^6.0.0",
    "@vue/eslint-config-typescript": "^7.0.0",
    "axios-mock-adapter": "^1.20.0",
    "eslint": "^7.20.0",
    "eslint-plugin-prettier": "^3.3.1",
    "eslint-plugin-vue": "^7.6.0",
    "node-sass": "^4.12.0",
    "prettier": "^2.2.1",
    "sass-loader": "^8.0.2",
    "typescript": "~4.1.5",
    "webpack-manifest-plugin": "^4.0.2",
    "webpack-node-externals": "^3.0.0"
  }

Answer 1

Note that Avoid Stateful Singletons rule applies not only to main app instance and store, but also to a router

Your current Router/index.ts creates stateful singleton. What you need instead is to create a "router factory" function so each server requests gets new router instance. Added benefit is that now you can pass a store instance into it

Router/index.ts

  import { createRouter, createWebHistory, createMemoryHistory } from "vue-router"
  import axios from "axios"
  import MockAdapter from "axios-mock-adapter"
  import { routes } from "./routes"
  import { isSSR } from "@/helpers"

  const createHistory = isSSR()
    ? createMemoryHistory
    : createWebHistory

  export default function (store) {
    const router = createRouter({ 
      routes, 
      history: createHistory(process.env.BASE_URL)
    })

    router.beforeEach(async (to, from, next) => {
      // do stuff with store (store comes from argument)
    })
  
    return router
  }

Note that both server and client bundle should use createSSRApp - if you use standard createApp, client side hydration will not work

Vue provides a createSSRApp method for use in client-side code to tell Vue to hydrate the existing static HTML instead of re-creating all the DOM elements

main.js

import { createSSRApp, h } from "vue"
import { isSSR } from "@/helpers"
import createRouter from "@/router"
import createStore from "@/store"
import axios from "axios"
import VueAxios from "vue-axios"
import App from "@/App.vue"

export default function () {

  const rootComponent = {
    render: () => h(App),
    components: { App },
  }

  const app = createSSRApp(rootComponent)
  const store = createStore()
  const router = createRouter(store)

  app.use(VueAxios, axios)
  app.use(router)
  app.use(store)

  app.provide("axios", app.config.globalProperties.axios)

  return {
    app,
    router,
    store,
  }
}

Answer 2

Your default export is a function

export default function () {

I think you wanted to do this instead:

export default new Vuex.Store({...})

If you want to keep it as a function you can also try store().commit but that'll just create a new Vuex instance everytime you call store()