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Computed property depends on vuex store. How to update the cached value?

Posted by: admin November 26, 2021 Leave a comment

Questions:

The value of this.$store.state.Auth.loginToken is modified by one of its child components. The initial value of this.$store.state.Auth.loginToken is undefined. But still, the update in its value has no effect in the cached value of navItems thus it always returns the second value.

computed: {
    navItems () {
        return this.$store.state.Auth.loginToken != undefined ?
        this.items.concat([
            { icon: 'add', title: 'Add new journal entry', to: '/' },
            { icon: 'power_settings_new', title: 'Logout', to: '/logout'}
        ]) :
        this.items.concat([
            { icon: 'play_arrow', title: 'Login', to: '/login' }
        ])
    }
}

Is there a better way to keep a watch on this.$store.state.Auth.loginToken so that it can be used same as navItems?

Answers:

I created a basic example of how you can use vuex getters and Auth token (codepen):

const mapGetters = Vuex.mapGetters;

var store = new Vuex.Store({
  state: {
    Auth: {
      loginToken: ''
    },
    menuItems: [
       { icon: 'home', title: 'Home', to: '/' },
       { icon: 'about', title: 'About', to: '/about' },
       { icon: 'contact', title: 'Contact', to: '/contact' }
    ]
  },
  mutations: {
    SET_LOGIN_TOKEN(state, data) {
      state.Auth.loginToken = 1
    }
  },
  getters: {
    menuItems(state, getters) {
      if(state.Auth.loginToken !== '') {
        return state.menuItems.concat([{
            icon: 'profile', title: 'Profile', to: '/profile'
        }])
      }
      return state.menuItems
    },
    loggedIn(state) {
      return state.Auth.loginToken !== ''
    }
  },
  actions: {
    doLogin({commit}) {
       commit('SET_LOGIN_TOKEN', 1)
    }
  }
});

new Vue({
  el: '#app',
  store,
  data: function() {
    return {
      newTodoText: "",
      doneFilter: false
    }
  },
  methods: {
    login() {
       this.$store.dispatch('doLogin')
    }
  },
  computed: {
   ...mapGetters(['menuItems', 'loggedIn'])
  }
})

This is just an example so you can ignore the actual login action. Also, the store should be a directory, the getters, mutations and actions should have their own files which are then imported in the index.js in the store like in this example