I have a store in Vuex with an empty state
const state = {
data: {
}
};
And a simple mutations for test to change value or add new data
const mutations = {
changeOrAdd(state, {key,value}) {
state.data[key] = value;
}
};
If I do a commit to changeOrAdd, it is added to state BUT it doesn't have reactivity.
I did a simple trick to change a default value
const state = {
data: {
change: 0
}
};
And in the mutation:
const mutations = {
changeValueAttr(state, {
key,
value
}) {
state.data[key] = value;
state.data.change++;
}
};
And everytime I change or add a new value, it looks like a reactivity.
But, exists a way to do this without a "default" variable and without this stupid trick?
To add a new data in store vue and make it with reactivity?
Thanks
Since your keys initially are not declared in data, Vue can't track the changes. You need to use Vue.set to reactively add properties, see change detection caveats:
import Vue from 'vue'
const mutations = {
changeOrAdd(state, {key, value}) {
Vue.set(state.data, key, value)
}
}
Related
I am passing a ref value to a composable function, updateableSetting. This has an initial value, settingA, but can be updated by the user. When updated, us it possible to have useFeature run again and return an updated feature value?
export default defineComponent({
setup() {
const updateableSetting = ref('settingA')
const { feature } = useFeature(updateableSetting.value)
}
})
Sure. Use a computed property
import { ref, defineComponent, computed} from 'vue'
const useFeature = (initialRef) => {
const feature = computed(() => initialRef.value + ' - I am always up to date!')
return {
feature
}
}
export default defineComponent({
setup() {
const updateableSetting = ref('settingA')
//make sure you don't pass .value here - pass the whole ref object instead
const { feature } = useFeature(updateableSetting)
return { feature }
}
})
If you mean "run a function everytime updatedValue changes", you can use
watch(
[updatedValue],
() => {console.log('updatedValue changed! doing some calculations...')}
)
I had same problem when using composables in nuxt 3.
In nuxt 3 new reactive state is available called useState. try useState instead of ref.
for more information see nuxt 3 document: useState nuxt3
I'm trying to figure out how to properly update a getter value when some other variable from VueX changes/updates.
Currently I'm using this way in a component to update:
watch: {
dates () {
this.$set(this.linedata[0].chartOptions.xAxis,"categories",this.dates)
}
}
So my getter linedata should be updated with dates value whenever dates changes. dates is state variable from VueX store.
The thing is with this method the value won't be properly updated when I changed route/go to different components. So I think it's better to do this kind of thing using the VueX store.
dates is updated with an API call, so I use an action to update it.
So the question is how can I do such an update from the VueX store?
EDIT:
I tried moving this to VueX:
async loadData({ commit }) {
let response = await Api().get("/cpu");
commit("SET_DATA", {
this.linedata[0].chartOptions.xAxis,"categories": response.data.dates1,
this.linedata[1].chartOptions.xAxis,"categories": response.data.dates2
});
}
SET_DATA(state, payload) {
state = Object.assign(state, payload);
}
But the above does not work, as I cannot set nested object in action this way...
Getters are generally for getting, not setting. They are like computed for Vuex, which return calculated data. They update automatically when reactive contents change. So it's probably best to rethink the design so that only state needs to be updated. Either way, Vuex should be updated only with actions/mutations
Given your example and the info from all your comments, using linedata as state, your action and mutation would look something like this:
actions: {
async loadData({ commit }) {
let response = await Api().get("/cpu");
commit('SET_DATA', response.data.dates);
}
}
mutations: {
SET_DATA(state, dates) {
Vue.set(state.linedata[0].chartOptions.xAxis, 'categories', dates[0]);
Vue.set(state.linedata[1].chartOptions.xAxis, 'categories', dates[1]);
}
}
Which you could call, in the component for example, like:
this.$store.dispatch('loadData');
Using Vue.set is necessary for change detection in this case and requires the following import:
import Vue from 'vue';
Theoretically, there should be a better way to design your backend API so that you can just set state.linedata = payload in the mutation, but this will work with what you have.
Here is a simple example of a Vuex store for an user.
export const state = () => ({
user: {}
})
export const mutations = {
set(state, user) {
state.user = user
},
unset(state) {
state.user = {}
},
patch(state, user) {
state.user = Object.assign({}, state.user, user)
}
}
export const actions = {
async set({ commit }) {
// TODO: Get user...
commit('set', user)
},
unset({ commit }) {
commit('unset')
},
patch({ commit }, user) {
commit('patch', user)
}
}
export const getters = {
get(state) {
return state.user
}
}
If you want to set the user data, you can call await this.$store.dispatch('user/set') in any Vue instance. For patching the data you could call this.$store.dispatch('user/patch', newUserData).
The getter is then reactively updated in any Vue instance where it is mapped. You should use the function mapGetters from Vuex in the computed properties. Here is an example.
...
computed: {
...mapGetters({
user: 'user/get'
})
}
...
The three dots ... before the function call is destructuring assignment, which will map all the properties that will the function return in an object to computed properties. Those will then be reactively updated whenever you call dispatch on the user store.
Take a look at Vuex documentation for a more in depth explanation.
I'm having trouble understanding how to interact with my local state from my vuex state. I have an array with multiple items inside of it that is stored in vuex state. I'm trying to get that data from my vuex state into my components local state. I have no problems fetching the data with a getter and computed property but I cannot get the same data from the computed property into local state to manipulate it. My end goal is to build pagination on this component.
I can get the data using a getters and computed properties. I feel like I should be using a lifecycle hook somewhere.
Retrieving Data
App.vue:
I'm attempting to pull the data before any components load. This seems to have no effect versus having a created lifecycle hook on the component itself.
export default {
name: "App",
components: {},
data() {
return {
//
};
},
mounted() {
this.$store.dispatch("retrieveSnippets");
}
};
State:
This is a module store/modules/snippets.js
const state = {
snippets: []
}
const mutations = {
SET_SNIPPETS(state, payload) {
state.snippets = payload;
},
}
const actions = {
retrieveSnippets(context) {
const userId = firebase.auth().currentUser.uid;
db.collection("projects")
.where("person", "==", userId)
.orderBy("title", "desc")
.onSnapshot(snap => {
let tempSnippets = [];
snap.forEach(doc => {
tempSnippets.push({
id: doc.id,
title: doc.data().title,
description: doc.data().description,
code: doc.data().code,
person: doc.data().person
});
});
context.commit("SET_SNIPPETS", tempSnippets);
});
}
}
const getters = {
getCurrentSnippet(state) {
return state.snippet;
},
Inside Component
data() {
return {
visibleSnippets: [],
}
}
computed: {
stateSnippets() {
return this.$store.getters.allSnippets;
}
}
HTML:
you can see that i'm looping through the array that is returned by stateSnippets in my html because the computed property is bound. If i remove this and try to loop through my local state, the computed property doesn't work anymore.
<v-flex xs4 md4 lg4>
<v-card v-for="snippet in stateSnippets" :key="snippet.id">
<v-card-title v-on:click="snippetDetail(snippet)">{{ snippet.title }}</v-card-title>
</v-card>
</v-flex>
My goal would be to get the array that is returned from stateSnippets into the local data property of visibleSnippets. This would allow me to build pagination and manipulate this potentially very long array into something shorter.
You can get the state into your template in many ways, and all will be reactive.
Directly In Template
<div>{{$store.state.myValue}}</div>
<div v-html='$store.state.myValue'></div>
Using computed
<div>{{myValue}}</div>
computed: {
myValue() { return this.$store.state.myValue }
}
Using the Vuex mapState helper
<div>{{myValue}}</div>
computed: {
...mapState(['myValue'])
}
You can also use getters instead of accessing the state directly.
The de-facto approach is to use mapGetters and mapState, and then access the Vuex data using the local component.
Using Composition API
<div>{{myValue}}</div>
setup() {
// You can also get state directly instead of relying on instance.
const currentInstance = getCurrentInstance()
const myValue = computed(()=>{
// Access state directly or use getter
return currentInstance.proxy.$store.state.myValue
})
// If not using Vue3 <script setup>
return {
myValue
}
}
I guess you are getting how Flux/Vuex works completely wrong. Flux and its implementation in Vuex is one way flow. So your component gets data from store via mapState or mapGetters. This is one way so then you dispatch actions form within the component that in the end commit. Commits are the only way of modifying the store state. After store state has changed, your component will immediately react to its changes with latest data in the state.
Note: if you only want the first 5 elements you just need to slice the data from the store. You can do it in 2 different ways:
1 - Create a getter.
getters: {
firstFiveSnipets: state => {
return state.snipets.slice(0, 5);
}
}
2 - Create a computed property from the mapState.
computed: {
...mapState(['allSnipets']),
firstFiveSnipets() {
return this.allSnipets.slice(0, 5);
}
}
I'm saving an array into local storage
and adding/removing from the array like.
I want the count of the array to update in the component as and when new items get added to the array in localstorage
I am using a computed property:
numOfCodes: {
// getter
get: function() {
let storageItems = localStorage.getItem("items");
if (storageItems) {
var items = JSON.parse(storageItems);
return items.length;
}
return 0;
}
}
The count is not changing as expected. it remains the same.
I have tried using vuex, but still have the issue. the goal is having the value react to the localstorage change
I think a solution to this would be to use vuex, I've mocked up an example below:
On your component:
computed: {
...mapGetters({
itemsCount: 'mockLocalStorage/itemsCount'
})
},
created() {
this.setItems(...);
},
methods: {
...mapActions({
setItems: 'mockLocalStorage/setItems'
})
}
In vuex:
state = {
items: []
};
getters = {
itemsCount: state => state.items.length
};
actions: {
setItems({ commit }, items) {
localStorage.setItem('items', items);
commit('setItems', items);
}
};
this.itemsCount would then be reactive in your component, and you could create a few more actions to add and remove individual items.
The localStorage does not share the reactivity system of Vue. This whole process is handled by Vue itself. See also here. I think you should be able to manually trigger a re-render by forcing Vue to update all of its components using forceUpdate. However, keep in mind that you would have to trigger the re-render whenever you update the localStorage or whenever you expect it to be updated.
Use a watcher.
props: ['storageItems', 'itemsLength'],
watch: {
storageItems: function(newVal, oldVal) {
this.storageItems = newVal
this.itemsLength = newVal.length
}
}
When I put this in my Vue component ...
// using store getter
computed: {
authenticated() {
return this.$store.getters.authenticated
}
}
... it works. The value for authenticated is reactive and the computed property returns true when the value in the vuex store is true.
This should work ... (and would be the right way according to the docs)
// using store state
computed: {
authenticated() {
return this.$store.state.authenticated
}
}
... but doesn't. The computed property is always false.
It doesn't even work on initial state, so I guess it has nothing to do with the action or mutation. The vuex store holds the correct values in the state and the getters (Firefox Vue DevTools).
My store looks like this:
const state = {
authenticated: authenticate.isAuthenticated(),
};
const getters = {
authenticated () {
return state.authenticated
}
};
const mutations = {
isAuthenticated (state, isAuthenticated) {
state.authenticated = isAuthenticated
}
};
So, it works with store getters but not with store state. Afaik the store state should be reactive as well.
Any idea what I might be doing wrong?
More as an aside to this discussion, vuex offers the mapGetters, mapState, mapActions, and mapMutations helper functions.
In the case of the authenticated getter, you would map it like:
import { mapGetters } from 'vuex
computed: {
...mapGetters({
authenticated: 'authenticated'
})
}
Helps to keep your code clean and concise, imo.
Assuming you construct your Vuex.Store as I do below, the computed works as expected using either state.authenticated or getters.authenticated.
The mutations section made no difference, so I took it out to make things minimal.
As Bert noted, your getter should take state as a parameter; otherwise, it is using the declared const, which is the same thing in this case, but deceptive to read.
const authenticate = {
isAuthenticated() {
return true;
}
};
const state = {
authenticated: authenticate.isAuthenticated()
};
const getters = {
authenticated (state) {
return state.authenticated;
}
};
const store = new Vuex.Store({
state,
getters
});
new Vue({
el: '#app',
store,
computed: {
authenticated() {
return this.$store.state.authenticated;
}
}
});
<script src="//unpkg.com/vue#latest/dist/vue.js"></script>
<script src="//unpkg.com/vuex#latest/dist/vuex.js"></script>
<div id="app">
Anything? {{authenticated}}
</div>
const state = {
authenticated: authenticate.isAuthenticated(),
};
The state is an object. An attribute in the object is trying to call the result of a function. This might be the problem, as it would be asking an object to invoke functions. Try setting it to a fixed value first, and change the state value by invoking a mutation when needed.
You could also try js object function call to invoke the authenticate.isAuthenticated() function inside the state object.
Details here: https://www.w3schools.com/js/js_function_call.asp
Possible solution:
const state = {
authenticated: function(){ return authenticate.isAuthenticated() },
};
I do not think the problem is with using getters or state. Since state ran correctly, getters should do the same since it is pointing to state. Have you exported getters from your store? That seems to be the likely issue. As previously mentioned, you ought to pass state as a parameter when using vuex getters