I have a component, which looks like this:
export default {
name: 'todos',
props: ['id'],
created () {
this.fetchData()
},
data() {
return {
}
},
computed: {
todos () {
return this.$store.state.todos[this.id]
}
},
methods: {
async fetchData () {
if (!this.$store.state.todos.hasOwnProperty(this.id)) {
await this.$store.dispatch('getToDos', this.id)
}
}
}
}
This is what's happening:
The component receives an id via props.
When the component loads I need to fetch some data based on the id
I have a created() hook from where I call a function fetchData() to fetch the data.
In methods, the fetchData() function dispatches an action to get the data. This gets and stores the data in Vuex store.
The computed property todos gets the data for this id.
The problem is that when the page first loads, the computed property todos shows up as undefined. If I change the page (client side) then the computed property gets the correct data from the store and displays it.
I am unable to understand why computed property doesn't update?
You could use following approach:
component.vue (and just render todoItem)
methods: {
async fetchData () {
const _this = this;
if (!this.$store.state.todos.hasOwnProperty(this.id)) {
this.$store.dispatch('getToDos', {id: this.id, callback: () => {
_this.todoItem = _this.$store.state.todos[_this.id]
}});
}
}
}
store.js
actions: {
getToDos: (context, payload) => {
// simulate fetching externally
setTimeout(() => {
context.commit("getToDos__", {newId: payload.id, task: "whatever" });
payload.callback();
}, 2000);
},
Base on here
When this hooks is called, the following have been set up: reactive data, computed properties, methods, and watchers. However, the mounting phase has not been started, and the $el property will not be available yet.
I think what might solve it is if you create a getter for todos.
So in your VueX Store add:
getters: {
todos(state) {
return state.todos;
}
};
And than in your computed use:
computed: {
todos () {
return this.$store.getters.todos[this.id]
}
}
Related
Essentially, in a Vue application, I have a page that lists Contacts. And a search form that is part of a header component. I capture the input search term as a state variable in the vuex store and track it as a computed variable.
I have a method to retrieve contacts that is called within the mounted hook. I want to call the same getContacts method again whenever the state search variable changes. Using a watcher to do this atm, but I have read that watching a computed value is not the right way. Wondering if there is a better way to do this. Script below.
<script>
import API from '#/utils/Api.js'
...
export default ({
...
tableData: [],
}
},
computed: {
search() {
return this.$store.getters.search;
}
},
mounted() {
this.getContacts();
},
methods: {
async getContacts() {
try {
const {data} = await API.get('/contacts?search=' + this.search)
this.tableData = data
} catch (e) {
console.error(e)
}
}
},
watch: {
search () {
this.getContacts();
}
}
})
</script>
Try to watch directly the state item and then pass the new value as parameter for the method, then use immediate:true to replace the mounted hook call :
export default ({
...
tableData: [],
}
},
methods: {
async getContacts(val) {
try {
const {data} = await API.get('/contacts?search=' + val)
this.tableData = data
} catch (e) {
console.error(e)
}
}
},
watch: {
'$store.getters.search': {
handler(newVal)
this.getContacts(newVal);
},
immediate:true
}
}
})
I am working on a product overview page, that send out an API-call based on the current Category you are looking at:
store.dispatch("tweakwise/fetchAPIAttributesLayeredNavigation", {
tweakwiseCategory,
this.pageNumber,
}
In my Store, the data from this API-call will be set in the following VueX Store State:
this.$store.state.tweakwise.tweakwiseLayeredNavigationAttributes: []
I want to react to this data in my front-end but my Computed methods do not seem to react to this change. As you can also see in the function below I added a Catch to prevent a "Non defined" error. The function, however, will not be called after the state has been set.
This computed property is also added to the Mount() op the component
computed: {
initialFetchProducts() {
this.fetchProducts(
this.$store.state.tweakwise?.tweakwiseLayeredNavigationAttributes || []
);
},
},
make computed property for state you want to watch,
than create watch() for this prop. In watch you can react on computed property change.
<template>
<div v-for="product in products"></div>
</template>
<script>
export default {
data: {
return {
products: [],
}
},
computed: {
tweakwiseLayeredNavigationAttributes() {
return this.$store.state.tweakwise.tweakwiseLayeredNavigationAttributes;
},
},
watch: {
// on every tweakwiseLayeredNavigationAttributes change we call fetchProducts
tweakwiseLayeredNavigationAttributes: {
handler(newValue, oldValue) {
this.fetchProducts(newValue);
},
deep: true, // necessary for watching Arrays, Object
immediate: true, // will be fired like inside mounted()
}
},
methods: {
async fetchProducts(params) {
const products = await axios.get('/api', params);
this.products = products;
}
}
};
</script>
I use Vue.js and have a component. I pass a prop "request" to that component:
<adjustments-list
v-if="request"
:request="request"
/>
In the component I'm able to do this:
<text-input
:value="request.id"
/>
It works that is the value of "id" is displayed.
In props section of component:
props: {
request: Object
In mounted hook of component:
async mounted () {
await this.refresh()
},
In refresh function of component:
async refresh () {
console.log('this.request.id =', this.request.id)
if (this.request.id) {
const data = await requestApi.getRequestResultAdjustmentByReqId(this.request.id)
}
},
The this.request.id is undefined.
I'm not sure why.
If the request property is asynchronously available to the component then, you have to use combination of watchers like:
// adjustments-list component
new Vue({
props: {
request: Object
},
data() {
return {
apiData: null
}
},
watch: {
request(newValue, _oldValue) {
this.refresh(newValue);
}
},
mounted: function () {
// Do something here
},
methods: {
refresh (request) {
if (request.id) {
// Using promise instead of async-await
requestApi.getRequestResultAdjustmentByReqId(request.id)
.then(() => this.apiData = data);
}
}
}
});
Also, note that, mounted should be a plain old JS function and not an async function. That's the lifecycle method of the component supposed to behave in particular way.
My goal is to pass a getter object inside asyncData, because I need to access the state to pass data to axios
Code example
export default {
async asyncData() {
let result = await $axios.$post('/api/test', { data: this.totalPrice })
},
computed: {
...mapGetters(["totalPrice"])
}
}
As you can see I want to access getter object in asyncData However I got
As indicated in the documentation...
Warning: You don't have access to the component instance through this inside asyncData because it is called before initiating the component.
Instead, use the context object provided
async asyncData ({ store }) {
const body = { data: store.getters.totalPrice }
const { data } = await $axios.$post('/api/test', body)
return data
}
Methods should be placed into methods to have the vue context:
export default {
methods : {
async asyncData() {
let result = await $axios.$post('/api/test', { data: this.totalPrice })
}
},
computed: {
...mapGetters(["totalPrice"])
}
}
If you want to do it onload use mounted (https://v2.vuejs.org/v2/guide/instance.html#Lifecycle-Diagram)
export default {
async mounted() {
let result = await $axios.$post('/api/test', { data: this.totalPrice })
},
computed: {
...mapGetters(["totalPrice"])
}
}
I'm having trouble understanding the following:
I have a store which contains variables needed for the application. In particular, there is a globalCompanies which stores:
globalCompanies: {
current: [],
all: [],
currentName: "",
}
Inside another component, I want to do the following:
mounted() {
this.$store.dispatch( "fetchUsers" );
var currentName = this.$store.state.globalCompanies.currentName;
console.log(currentName);
},
However, this just shows as empty. I know the value is there because I have computed which returns the currentName and it works fine inside the view itself. It just doesn't like the fact that it's in the mounted component.
Where am I going wrong and what can I do to resolve this issue? I really need to capture the companies Name in order to use it for some real time events.
As a result of our discussion:
In the question Vuex state value, accessed in component's mounted hook, returns empty value, because it is set in an async action which does not resolve before mounted executes.
When you need to trigger some function when async action in Vuex resolves with a value, you can achieve it using watch on a computed property, which returns a value from your Vuex state. When a value in store changes, the computed property reflects these changes and watch listener executes:
const store = new Vuex.Store({
state: {
globalCompanies: {
test: null
}
},
mutations: {
setMe: (state, payload) => {
state.globalCompanies.test = payload
}
},
actions: {
pretendFetch: ({commit}) => {
setTimeout(() => {
commit('setMe', 'My text is here!')
}, 300)
}
}
})
new Vue({
el: '#app',
store,
computed: {
cp: function() { // computed property will be updated when async call resolves
return this.$store.state.globalCompanies.test;
}
},
watch: { // watch changes here
cp: function(newValue, oldValue) {
// apply your logic here, e.g. invoke your listener function
console.log('was: ', oldValue, ' now: ', newValue)
}
},
mounted() {
this.$store.dispatch('pretendFetch');
// console.log(this.cp, this.$store.state.globalCompanies.test); // null
// var cn = this.$store.state.globalCompanies.test; // null
// console.log(cn) // null
}
})
<script src="https://cdnjs.cloudflare.com/ajax/libs/vue/2.3.0/vue.js"></script>
<script src="https://unpkg.com/vuex#2.3.1"></script>
<div id="app">
{{ cp }}
</div>
VueJS - Accessing Store Data Inside Mounted
Ran into this issue and it turned out to be a scope issue.
Store:
export default () => {
items:[],
globalCompanies:{
current:[],
all:[],
currentName: "Something"
},
ok: "Here you go"
}
Getters:
export default {
getGlobalCompanies(state){
return state.globalCompanies;
}
}
Mounted: This works...
mounted() {
// Initialize inside mounted to ensure store is within scope
const { getters } = this.$store;
const thisWorks = () => {
const globalCompanies = getters.getGlobalCompanies;
}
},
This is Bad: Reaching for the store outside the mounted scope
mounted() {
function ThisDontWork() {
const { getters } = this.$store; // this.$store == undefined
}
ThisDontWork();
},