Develop Reference

Initialize array data from array prop in a Vue component

In my Vue component I have an array (of objects) prop called selectedSuppliers. I want to initialize a data prop called suppliers to selectedSuppliers, but any subsequent changes to suppliers should not propogate to selectedSuppliers.
I tried the following
props: {
selectedSuppliers: {
type: Array,
required: true
},
},
data () {
return {
selected: [...this.selectedSuppliers],
}
}
But it doesn't work. What is the correct way to initialize an array data property to an array prop?

If selectedSuppliers is an array of object, then the spread operator only performs a shallow copy of this array. It means that updating any object of suppliers will update the content of selectedSuppliers.
You can take a look at this short post.

This might work,
props: {
selectedSuppliers: {
type: Array,
required: true
},
},
data () {
return {
selected: this.selectedSuppliers.map(o => Object.assign({}, o)
}
}

Updating child array in reducer using React Context

I am doing some filtering using React Context and I am having some difficulty in updating a child's array value when a filter is selected.
I want to be able to filter by a minimum price, which is selected in a dropdown by the user, I then dispatch an action to store that in the reducers state, however, when I try and update an inner array (homes: []) that lives inside the developments array (which is populated with data on load), I seem to wipe out the existing data which was outside the inner array?
In a nutshell, I need to be able to maintain the existing developments array, and filter out by price within the homes array, I have provided a copy of my example code before, please let me know if I have explained this well enough!
export const initialState = {
priceRange: {
min: null
},
developments: []
};
// Once populated on load, the developments array (in the initialState object)
// will have a structure like this,
// I want to be able to filter the developments by price which is found below
developments: [
name: 'Foo',
location: 'Bar',
distance: 'xxx miles',
homes: [
{
name: 'Foo',
price: 100000
},
{
name: 'Bar',
price: 200000
}
]
]
case 'MIN_PRICE':
return {
...state,
priceRange: {
...state.priceRange,
min: action.payload
},
developments: [
...state.developments.map(development => {
// Something here is causing it to break I believe?
development.homes.filter(house => house.price < action.payload);
})
]
};
<Select onChange={event=>
dropdownContext.dispatch({ type: 'MIN_PRICE' payload: event.value }) } />

You have to separate homes from the other properties, then you can apply the filter and rebuild a development object:
return = {
...state,
priceRange: {
...state.priceRange,
min: action.payload
},
developments: state.developments.map(({homes, ...other}) => {
return {
...other,
homes: homes.filter(house => house.price < action.payload)
}
})
}

How to put return value into another return value in JS vue

I want the "topic1" to be the value of my breed name and key, but when I try to put this.topic1 to replace the manual typing, it shows nothing.
Or there are any other method to have my button name same as my retrieve API param, and sent it name when I click it?
new Vue({
el: '#app2',
components: { Async },
data() {
return {
topic1: null,
topic2: null,
currentBreed: 0,
breeds: [
{ name: this.topic1 , key: this.topic1 },
{ name: "German Shepherd", key: "germanshepherd" },
{ name: "Husky", key: "husky" },
{ name: "Pug", key: "pug" },
{ name: "(Error)", key: "error" },
]
}
},
async created() {
try {
this.promise = axios.get(
"https://k67r3w45c4.execute-api.ap-southeast-1.amazonaws.com/TwitterTrends"
);
const res = await this.promise;
this.topic1 = res.data[0].Trends;
this.topic2 = res.data[1].Trends;
} catch (e) {
console.error(e);
}
},
async mounted () {
let test = this.topic1;
},
computed: {
breedKey() {
return this.breeds[this.currentBreed].key;
}
}
})

There are several problems here.
The data function is called just once, when the corresponding Vue instance is created. Within that function you can get a reference to its Vue instance via this. At that point some properties, such as those corresponding to props, will already exist. However, others won't.
The object returned from data is used to create new properties on the instance. In this case you're creating 4 properties: topic1, topic2, currentBreed and breeds. Vue creates those properties based on that returned object, so they won't exist until after the data function is run.
So when you write { name: this.topic1 , key: this.topic1 }, within that data function you're attempting to access a property called topic1 that doesn't exist yet. As such it will have a value of undefined. So you're creating an entry equivalent to { name: undefined , key: undefined },.
Further, there is no link back to topic1. That object won't be updated when the value of topic1 changes.
It's also worth noting a few points about timing.
The data function will be called before the created hook, so the axios call isn't made until after the data properties are populated.
An axios call is asynchronous.
Using await may make the code a little easier to read but the 'waiting' is mostly just an illusion. The remaining code inside the function won't run until the awaited promise is resolved but that won't cause anything outside of the function to wait. await is equivalent to using then.
The component will render just after the created hook is called. This is synchronous, it won't wait for the axios request. The mounted hook will then be called, all before the axios call has completed.
All of this means you may need to adjust your template to handle the case where the axios call hasn't completed yet as it will initially render prior to the values of topic1 and topic2 being available.
Specifically addressing the breeds property you have a few options. One is to inject the values in once the value has loaded:
breeds: [
{ name: "" , key: "" }, // Initially empty values
{ name: "German Shepherd", key: "germanshepherd" },
// ...
const res = await this.promise;
this.topic1 = res.data[0].Trends;
this.topic2 = res.data[1].Trends;
this.breeds[0].name = this.breeds[0].key = this.topic1;
Another is to use a computed property for breeds (you'd remove it from the data for this):
computed: {
breeds () {
return [
{ name: this.topic1 , key: this.topic1 },
{ name: "German Shepherd", key: "germanshepherd" },
{ name: "Husky", key: "husky" },
{ name: "Pug", key: "pug" },
{ name: "(Error)", key: "error" },
]
}
}
As we're using a computed property it will be updated when topic1 changes as it's a reactive dependency.
Using a computed property is probably the most natural solution in this case but there are other tricks you can use to get this to work.
For example, you could use property getters for the two properties in that first breed object (that's JavaScript property getters, nothing to do with Vue):
data () {
const vm = this;
return {
topic1: null,
topic2: null,
currentBreed: 0,
breeds: [
{
get name () {
return vm.topic1;
},
get key () {
return vm.topic1;
}
},
{ name: "German Shepherd", key: "germanshepherd" },
{ name: "Husky", key: "husky" },
{ name: "Pug", key: "pug" },
{ name: "(Error)", key: "error" },
]
}
},
I'm not advocating this approach for your use case but it is an interesting way to do it that can sometimes be useful. The key thing to note is how the dependency on topic1 is evaluated only when the properties name and key are accessed, not when the data function is executed. This allows topic1 to be registered as a dependency of whatever is accessing name and key, e.g. during rendering.

Vuex Getters doesn't call state

I trying to return back sorted data (which is the already defined state) in a list with the help of a getter, then assign it to the html list in my vue, but it seems it's empty when I check with the vuex tools.
I don't know what am doing wrong.
Below is my store.js file
export default {
namespaced: true,
state:{
displayChatMessages: [],
},
mutations:{
create(state, payload) {
state.displayChatMessages.push(payload)
},
reset(state){
state.displayChatMessages = []
},
},
actions :{
getAllData:({commit}, payload) => {
commit('create',payload)
},
},
getters:{
filteredChatMessages: state => (chatID) => {
return state.displayChatMessages[0]
.filter(el => el.groupid === chatID).sort((l,r)=> l.timestamp - r.timestamp)
},
},
}
Then, after, I call it in the computed area like below :
...mapGetters('chatMessages',['filteredChatMessages']),
Then , I call the Getter inside my function , like below :
getFilteredMessages: function() {
let vm = this
return vm.filteredChatMessages(vm.groupID)
},
Then afterwards, then I set the getFilteredMessages() to the list , getFilteredMessages() , is also defined in the computed section.
But when I look into my vuex tools , I don't see it as an array :
What am I doing wrong ?

Update dynamic components disabled state based on Vuex state value

I have no idea if what I'm doing is correct or not, but here's a simplified version of what I'm trying to do:
I want to have 3 file inputs, with the 2nd and 3rd disabled until the 1st one has had a file selected.
I've tried to do is set the Vuex state variable to whatever the first file input is has selected, but upon doing that the other 2 inputs don't update their disabled state.
I have some file inputs that are created dynamically, like so:
Vue.component('file-input', {
props: ['items'],
template: `<div><input type="file" v-on:change="fileSelect(item)" v-bind:id="item.id" v-bind:disabled="disabledState"></div>`,
methods: {
fileSelect: function(item) {
store.commit('fileSelect', file);
}
},
computed: {
disabledState: function (item) {
return {
disabled: item.dependsOn && store.getters.getStateValue(item.dependsOn)
}
}
}
}
The data for the component is from the instance:
var vm = new Vue({
data: {
items: [
{ text: "One", id: "selectOne" },
{ text: "Two", id: "selectTwo", dependsOn: "fileOne" },
{ text: "Three", id: "selectThree", dependsOn: "fileOne" }
}
});
Now, notice the "dependsOn". In the Vuex store, I have a corresponding state item:
const store = new Vuex.Store({
state: {
files: [
{
fileOne: null
}
]
},
mutations: {
fileSelect(state, file) {
state.files.fileOne = file;
}
},
getters: {
getStateValue: (state) => (stateObject) => {
return state.files.findIndex(x => x[stateObject] === null) === 0 ? true : false;
}
}
});
Now, the above works when everything is first initialized. But once the first input has something selected, the other two inputs don't change.
I'm not sure how to update the bindings once a mutation of the state occurs.

I think you need to refactor your mutation to make the state property mutable, like this:
fileSelect(state, file) {
Vue.set(state.files[0].fileOne, file);
}

Well, I figured it out...
Because my state object is an array of objects, I can't just change one of the property's values with state.files.fileOne. I needed to do state.files[0].fileOne.