Q:

How can I update state in vuex ? vue.js 2

My vue component is like this :
<template>
    <div>
        <div class="row">
            <div class="col-sm-3">
                <div class="form-group">
                    <label for="status" class="sr-only">Status</label>
                    <select class="form-control" v-model="selected" @change="filterByStatus()">
                        <option value="">All Status</option>
                        <option v-for="status in orderStatus" v-bind:value="status.id">{{ status.name }}</option>
                    </select>
                </div>
            </div>
        </div>
        ...
    </div>
</template>

<script>
    import { mapActions, mapGetters } from 'vuex';
    export default {
        ...
        data() {
            return { selected: '' }
        },
        methods: {
            filterByStatus: function() {
                this.$store.state.status = this.selected
            }
        }
    }
</script>

My modules order vuex is like this :
import { set } from 'vue'
import order from '../../api/order'
import * as types from '../mutation-types'

const state = {
    status: ''
}
const getters = {
    ...
}
const actions = {
    ...
}

const mutations = {
    ...
}

export default {
    state,
    getters,
    actions,
    mutations
}

I use this : this.$store.state.order.status = this.selected, to update state when executed, but there exist error like this :

[Vue warn]: Error in callback for watcher "function () { return
  this._data.$$state }":  (found in )
Error: [vuex] Do not mutate vuex store state outside mutation
  handlers.

How can I solve it?
I want update state, because I want the value used by component another

A:

You must have received this error because of enabling strict mode in your vuex store setup. 
This, however, is a good practice. You must not modify state except from within a mutation. 
So to use the newly setup store; have a mutation in like:
const mutations = {
   mutateOrderStatus: function (state, payload) {
      state.order.status = payload
   }
}

const actions = {
   updateOrderStatusAction: function ({commit}, payload) {
      commit('mutateOrderStatus', payload)
   }
}

Now include it in your component like:
...
methods: {
  ...mapActions([ // spread operator so that other methods can still be added.
    'updateOrderStatusAction'
  ]),
  filterByStatus: function() {
    this.updateOrderStatusAction(this.selected)
  }
}

Note: you might need babel and babel-preset-es2015 installed to make use of spread operator: ....

