Vue & Vuex - How to enable form submit on any input / state change?

Question

I have a form with a submit button that is disabled by default. How do I make it enabled by any changes, without setting up a watcher for each input or some other way??

The Vuex mapState is empty when the template is mounted or created, so I can not deep clone that and compare with deep-diff for instance.. (also I did read its bad practice to deep clone states into variables).

My button:

<v-btn color="green" @click="onUpdateProfile" :disabled="!anyInputsChanged" :loading="false">Save</v-btn>

My input fields:

<InputField
  label="Förnamn"
  v-model="first_name"
/>
<InputField
  label="Efternamn"
  v-model="last_name"
/>

My script

import { mapState } from 'vuex'
import { mapFields } from 'vuex-map-fields'

import FormCard from '@/components/FormCard.vue'
import InputField from '@/components/base_components/InputField.vue'

export default {
  components: {
    FormCard,
    InputField,
  },
  data () {
    return {
      loading: true,
      isDisabled: true,
    }
  },
  computed: {
    ...mapState(['user', 'userProfile']),
    ...mapFields([
        'userProfile.first_name',
        'userProfile.last_name',
        'userProfile.fortnox_data.api_key'
    ]),
  },
  watch: {
  },
  mounted: function() {
    this.loading = false;
  },
  methods: {
    onUpdateProfile () {
      this.$store.dispatch('updateUserData', {
        id: this.user.uid,
        first_name: this.userProfile.first_name,
        last_name: this.userProfile.last_name,
        updated_at: new Date().toISOString(),
      })
    },
  }
}

the "anyInputsChanged" variable / computed / whatever I have not defined because I do not know how to. And bascially thats my question.. I want to enable "Submit" if any input element has changed, and disable if they all are unchanged.

Answer 1

Assuming you're using the basic updateField mutation, you could add a Vuex subscriber to listen for any commits and update an extra piece of state.

For example

import Vue from 'vue';
import Vuex from 'vuex';

import { getField, updateField } from 'vuex-map-fields';

Vue.use(Vuex);

const store = new Vuex.Store({
  strict: true,
  state: {
    modified: false, // 👈 add this one
    userProfile: {
      // whatever you got
    }
  },
  getters: {
    getField,
  },
  mutations: {
    updateField,
    setModified: (state, modified) => state.modified = !!modified
  },
  // actions, etc
});

// subscribe to "updateField" mutations
store.subscribe((mutation, state) => {
  if (mutation.type === "updateField") {
    store.commit("setModified", true)
  }
})

export default store

You can then use the modified state to control your button. Super simple example but you'd probably want to use mapState or similar.

<v-btn 
  color="green"
  @click="onUpdateProfile"
  :disabled="!$store.state.modified"
  :loading="false"
>Save</v-btn>

The last thing to do after that would be to commit modified back to false in your updateUserAction action to reset the state.