Returning data from a Vuex action - vue.js

Can I return data from a Vuex action or do I need to update the store?
I've got an action defined but it returns no data:
getData() {
return { "a" : 1, "b" : 2 }
}

You can actually return data from an action. From the documentation:
Actions are often asynchronous, so how do we know when an action is
done? And more importantly, how can we compose multiple actions
together to handle more complex async flows?
You should return a promise and the data in the resolve() method:
actions: {
actionA () {
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve({ name: 'John Doe' })
}, 1000)
})
}
}
And use it this way:
store.dispatch('actionA').then(payload => {
console.log(payload) /* => { name: 'John Doe' } */
})

Your code will work if the code that calls your action uses either 'await' or a callback.
For example:
const result = await store.dispatch('getData');
The main takeaway being that actions return promises even if the action isn't doing any asynchronous work!

Related

Vuejs created and mounted doesn't work properly even if at the same level than methods

I'm experiencing a strange behaviour with created() and mounted() in Vue.js. I need to set 2 lists in created() - so it means those 2 lists will help me to create a third list which is a merge.
Here is the code :
// return data
created () {
this.retrieveSellOffers();
this.getAllProducts();
},
mounted () {
this.mergeSellOffersProducts();
},
methods: {
retrieveSellOffers() {
this.sellerId = localStorage.sellerId;
SellOfferServices.getAllBySellerId(this.sellerId)
.then((response) => {
this.sellOffers = response.data;
console.log("this.sellOffers");
console.log(this.sellOffers);
})
.catch((e) => {
console.log(e);
});
},
getAllProducts() {
ProductServices.getAll()
.then((response) => {
this.products = response.data;
console.log("this.products");
console.log(this.products);
})
.catch((e) => {
console.log(e);
});
},
mergeSellOffersProducts () {
console.log(this.products) // print empty array
console.log(this.sellOffers) // print empty array
for (var i = 0; i < this.sellOffers.length; i++) {
if (this.sellOffers[i].productId === this.products[i]._id) {
this.arr3.push({id: this.sellOffers[i]._id, price: this.sellOffers[i].price, description: this.products[i].description});
}
}
this.arr3 = this.sellOffers;
},
}
//end of code
So my problem is when I enter in mergeSellOffersProducts(), my 2 lists are empty arrays :/
EDIT :
This way worked for me :
async mounted() {
await this.retrieveSellOffers();
await this.getAllProducts();
this.mergeSellOffersProducts();
},
methods: {
async retrieveSellOffers() {
this.sellerId = localStorage.sellerId;
this.sellOffers = (await axios.get('link/api/selloffer/seller/', { params: { sellerId: this.sellerId } })).data;
},
async getAllProducts() {
this.products = (await axios.get('link/api/product')).data;
},
}
I think the reason is: Vue does not wait for the promises to resolve before continuing with the component lifecycle.
Your functions retrieveSellOffers() and getAllProducts() contain Promise so maybe you have to await them in the created() hook:
async created: {
await this.retrieveSellOffers();
await this.getAllProducts();
}
So I tried to async my 2 methods :
async retrieveSellOffers() {
this.sellerId = localStorage.sellerId;
this.sellOffers = (await axios.get('linkhidden/api/selloffer/', { params: { sellerId: '615b1575fde0190ad80c3410' } })).data;
console.log("this.sellOffers")
console.log(this.sellOffers)
},
async getAllProducts() {
this.products = (await axios.get('linkhidden/api/product')).data;
console.log("this.products")
console.log(this.products)
},
mergeSellOffersProducts () {
console.log("here")
console.log(this.sellOffers)
console.log(this.products)
this.arr3 = this.sellOffers;
},
My data are well retrieved, but yet when I enter in created, the two lists are empty...
You are calling a bunch of asynchronous methods and don't properly wait for them to finish, that's why your data is not set in mounted. Since Vue does not await its lifecycle hooks, you have to deal with the synchronization yourself.
One Vue-ish way to fix it be to replace your method mergeSellOffersProducts with a computed prop (eg mergedSellOffersProducts). Instead of generating arr3 it would simply return the merged array. It will be automatically updated when products or sellOffers is changed. You would simply use mergedSellOffersProducts in your template, instead of your current arr3.
If you only want to update the merged list when both API calls have completed, you can either manually sync them with Promise.all, or you could handle this case in the computed prop and return [] if either of the arrays is not set yet.
When you're trying to merge the 2 lists, they aren't filled up yet. You need to await the calls.
async created () {
await this.retrieveSellOffers();
await this.getAllProducts();
},
async mounted () {
await this.mergeSellOffersProducts();
},

How can i pass parameters from method to action in vuejs vuex

I have to files with this code:
Users.vue
methods: {
obtenerUsuarios() {
console.log('Obtener Usuarios')
this.$store
.dispatch('auth/getValidToken')
.then((data) => {
console.log(data). // Console First Message
this.$store
.dispatch('user/fetchUsers', data)
.then((response) => {
this.items = response.data
})
.catch((error) => {
console.log(error)
})
})
.catch((error) => {
console.log('Error: ' + error)
})
},
},
Console Firsts Mesagge show me a json web token in console that is ok.
When i dispatch 'user/fetchUsers in
user.js
export const actions = {
fetchUsers({ jwt }) {
console.log('Action JWT:' + jwt) //Second console.log
return UserService.getUsers(jwt)
},
}
The second messaje show me: Action JWT:undefined in the console
if i change the line two to
fetchUsers(jwt) {
The second messaje show me: Action JwT:[object Object]
I need to pass a json web token from Users.vue method to fetchUsers action y user.js
I will to appreciate any help
Jose Rodriguez
Your action method currently declares the data in the first argument (and no second argument), but actions receive the Vuex context as its first argument. The data payload is in the second argument:
const actions = {
//fetchUsers(data) {} // DON'T DO THIS (1st arg is for context)
fetchUsers(context, data) {}
}

How to use debounce with Vuex?

I am trying to debounce a method within a Vuex action that requires an external API.
// Vuex action:
async load ({ state, commit, dispatch }) {
const params = {
period: state.option.period,
from: state.option.from,
to: state.option.to
}
commit('SET_EVENTS_LOADING', true)
const res = loadDebounced.bind(this)
const data = await res(params)
console.log(data)
commit('SET_EVENTS', data.collection)
commit('SET_PAGINATION', data.pagination)
commit('SET_EVENTS_LOADING', false)
return data
}
// Debounced method
const loadDebounced = () => {
return debounce(async (params) => {
const { data } = await this.$axios.get('events', { params })
return data
}, 3000)
}
The output of the log is:
[Function] {
cancel: [Function]
}
It is not actually executing the debounced function, but returning to me another function.
I would like to present a custom debounce method which you can use in your vuex store as
let ongoingRequest = undefined;
const loadDebounced = () => {
clearTimeout(ongoingRequest);
ongoingRequest = setTimeout(_ => {
axios.get(<<your URL>>).then(({ data }) => data);
}, 3000);
}
This method first ensures to cancel any ongoing setTimeout in the pipeline and then executes it again.
This can be seen in action HERE

Can I dispatch vuex action inside getter function?

I want to dispatch action inside getter function.
1. Is it possible and right.
2. If yes how can I do it?
I guess it will be something like this dispatch('GET_BOOKS');
const getters = {
getAllBooksDispatch: (state, getters, dispatch) => {
if (state.books === null) {
dispatch('GET_BOOKS');
}
return state.books
},
};
But it does not work.
So my store file looks like this.
const initialState = {
books: null
};
const getters = {
getAllBooksDispatch: (state, getters, dispatch) => {
if (state.books === null) {
dispatch('GET_BOOKS');
}
return state.books
},
};
const mutations = {
SET_BOOKS: (state,{data}) => {
console.log('SET_BOOKS mutations')
state.books = data;
},
};
const actions = {
GET_BOOKS: async ({ commit }) => {
let token = users.getters.getToken;
let query = new Promise((resolve, reject) => {
axios.get(config.api + 'books', {token}).then(({data}) => {
if (data) {
commit('SET_BOOKS', {data: data})
resolve()
} else {
reject(data.message);
}
}).catch(() => {
reject('Error sending request to server!');
})
})
},
};
No, you can't. At least not the way you want to. The third argument in a getter is the rootState object when using modules, not dispatch. Even if you find a way to dispatch an action inside a getter it won't work the way you expect. Getters must be synchronous, but actions can be (and in this example are) asynchronous. In your example, GET_BOOKS would be dispatched but the getter would still return state.books as null.
I'd recommend handling this sort of lazy-loading outside of the Vuex store.

How can my vuex mutation dispatch a new action?

How can my vuex mutation dispatch a new action or how can my action get read access to the store?
Basically I've got a action that calls an mutation:
updateSelectedItems: (context, payload) => {
context.commit('updateSelectedItems', payload);
},
And the mutation that updates the list. It also gets any new items. I need to do something with these new items:
updateSelectedItems: (state, payload) => {
var newItems = _.differenceWith(payload, state.selectedItems, function (a, b) {
return a.name === b.name;
});
state.selectedItems = _.cloneDeep(payload);
_.each(newItems, (item) => {
// How do I do this??
context.dispatch('getItemDetail', item.name)
});
},
It's really not best practice to make your mutations do too much. It's best if they're super-simple and generally do one thing. Let your actions take care of any multi-step processes that might affect the state.
Your example would make more sense structured like this:
actions: {
updateSelectedItems(context, payload) {
var selectedItems = context.state.selectedItems;
var newItems = _.differenceWith(payload, selectedItems, (a, b) => {
return a.name === b.name;
});
context.commit('setSelectedItems', payload);
_.each(newItems, (item) => {
context.dispatch('getItemDetail', item.name)
});
},
getItemDetail(context, payload) {
// ...
}
},
mutations: {
setSelectedItems(state, payload) {
state.selectedItems = _.cloneDeep(payload);
}
}
If you really need to dispatch something from inside a mutation (which I'd highly recommend not doing), you can pass the dispatch function to the mutation as part of the payload.
It is technically possible using this to call dispatch or commit (or few others) ... i'm only mentioning this for anybody who comes here and needs it for their specific use case.
In my situation i'm using fiery-vuex library which actually passes a function as the payload that will return the updated data, i use this along with a refresh_time key in the db to determine when to refresh certain user data
SOME_MUTATION( state, getData() ){
const new_data = getData()
if( new_data.refresh_time > state.user.refresh_time ){
this.dispatch( 'refreshFromOtherStateMeta', state.user.id )
}
state.user = new_data
}