I am using Vue.js 2.6 with the vue-router component. I have a search form as follows:
<form class="search-form" #submit.prevent="search">
<div class="form-group">
<input type="text" class="form-control" v-model="term" placeholder="Search">
</div>
</form>
And here is my script:
<script>
export default {
data() {
return {
term: this.$route.query.term,
items: []
}
},
created() {
if (this.term != null) {
this.search()
}
},
watch: {
'$route.query.term'() {
this.term = this.$route.query.term
this.search()
}
},
methods: {
search: function () {
window.axios.get('/images/search', {
params: {
term: this.term
}
})
.then(response => {
this.$router.push({query: { 'term' : this.term}})
this.items = response.data.collection.items
})
.catch(error => {
return error
})
}
}
}
</script>
What I am trying to achieve with this code is the following:
User submits form, the search() function is called. The URL is updated with the query param, e.g. /search?term=<term>. This is working but the search() function is being called twice.
User carries out several searches, then presses the back button. The search field in the form is updated and the search is carried out. This is working but the search() function is being called twice.
User manually enters query param in the URL bar. The search field in the form is populated and the search is carried out. This is working.
Where the search() function is being called twice, this is due to the watch() function, which is designed to watch changes to the URL bar. I am not sure how to combine this function correctly with the search() function.
In watch, you can compare new value with old value, and only perform search when new value is different with old value
watch: {
'$route.query.term'(newVal, oldVal) {
if (newVal != oldVal) {
this.term = this.$route.query.term
this.search()
}
}
},
To make it call only 1 for 1st case, you might want to separate button click handler with real search call
<script>
export default {
data() {
return {
term: this.$route.query.term,
items: []
}
},
created() {
if (this.term != null) {
this.performSearch()
}
},
watch: {
'$route.query.term': {
handler: function(newVal, oldVal) {
if (newVal != oldVal) {
this.term = this.$route.query.term
this.performSearch()
}
},
immediate: true
}
},
methods: {
search: function () {
// this is call when user click search Button
this.$router.push({query: { 'term' : this.term}})
},
performSearch() {
// perform actual searcch
window.axios.get('/images/search', {
params: {
term: this.term
}
})
.then(response => {
this.items = response.data.collection.items
})
.catch(error => {
return error
})
}
}
}
</script>
Related
backAction = () => {
if (this.props.navigation.isFocused() && !this.state.otpScreen) {
this.setState({ showLoginScreen: true });
return true;
} else if(this.state.showLoginScreen) {
this.props.navigation.dispatch(CommonActions.reset({
index: 0,
routes: [
{ name: 'Login' },
],
}))
return false;
}
};
the code above is for action that should be done by the hardware back press, at first it should show the one screen and on the second press it should exit the app, both otp screen and login screen are on the same component, I'm just hiding based on the condition ...
at the first time it is working as per the condition but for the second time it's not.
componentDidMount() {
this.focusListener = this.props.navigation.addListener('focus', () => {
this.setState({
mobile: '',
showLoginScreen: true,
});
});
this.getDataFromStorage();
AsyncStorage.setItem('countryCode', '+91');
BackHandler.addEventListener(
"hardwareBackPress",
this.backAction
);
}
componentWillUnmount() {
clearInterval(this.interval)
BackHandler.addEventListener('hardwareBackPress', () => { return false })
}
can anyone pls help me how to do this,thanks in Advance
I guess your problem is that you can't access the 'current' value of a state inside a listener.
More Details here
Try to use a Reference instead of a state
I have a QR code creating page. I want my QR codes to be created dynamically by user input. But I don't want to instantly create a QR code. I want to wait my user to finish writing then after one second i will generate the QR code. So I have a template like below:
<div class="app">
<qrcode-vue :value="genaratedQrCode"></qrcode-vue>
<input type="text" v-model="qrCodeInput" />
</div>
And my script:
import QrcodeVue from 'qrcode.vue';
export default {
data() {
return {
genaratedQrCode: '',
qrCodeInput: '',
isInputFunctionRunning: false
}
},
watch: {
async qrCodeInput() {
if (this.isInputFunctionRunning) {
return;
}
this.isInputFunctionRunning = true;
await new Promise(r => setTimeout(r, 1000));
this.genaratedQrCode = this.qrCodeInput;
this.isInputFunctionRunning = false;
}
}
components: {
QrcodeVue,
},
}
Apparently the code is not working. It generated the QR code every one seconds. What I want is waiting till user finished, then updating after 1 seconds.
You have to use .lazy modifier :
<input type="text" v-model.lazy="qrCodeInput" />
If you want to wait some delay try this :
import QrcodeVue from 'qrcode.vue';
function debounce (fn, delay) {
var timeoutID = null
return function () {
clearTimeout(timeoutID)
var args = arguments
var that = this
timeoutID = setTimeout(function () {
fn.apply(that, args)
}, delay)
}
}
export default {
data() {
return {
genaratedQrCode: '',
qrCodeInput: '',
isInputFunctionRunning: false
}
},
watch: {
qrCodeInput:debounce(function() {
if (this.isInputFunctionRunning) {
return;
}
this.isInputFunctionRunning = true;
this.genaratedQrCode = this.qrCodeInput;
this.isInputFunctionRunning = false;
},1000)
}
components: {
QrcodeVue,
},
}
This is based on this answer;
I am struggeling with a proper solution which requires an advanced parent-child communication in vuejs. There can be many different parent components which has a logic how to save data. From the other side there will be only one child component which has a list of elements and a form to create new elements but it doesn't know how to save the data.
The question is: Is there any other way (better approach) to have the same functionality but to get rid of this.$refs.child links. For example I am wondering if I can just pass a function (SaveParent1(...) or SaveParent2(...)) to the child component. But the problem is the function contains some parent's variables which won't be available in child context and those variables could be changed during the runtime.
Just few clarifications:
The methods SaveParent1 and SaveParent2 in real life return
Promise (axios).
The child-component is like a CRUD which is used
everywhere else.
At the moment the communication looks like that: CHILD -event-> PARENT -ref-> CHILD.
Bellow is the example:
<div id="app">
<h2>😀Advanced Parent-Child Communication:</h2>
<parent-component1 param1="ABC"></parent-component1>
<parent-component2 param2="XYZ"></parent-component2>
</div>
Vue.component('parent-component1', {
props: { param1: { type: String, required: true } },
methods: {
onChildSubmit(p) {
// Here will be some logic to save the param. Many different parents might have different logic and all of them use the same child component. So child-component contains list, form and validation message but does not know how to save the param to the database.
var error = SaveParent1({ form: { p: p, param1: this.param1 } });
if (error)
this.$refs.child.paramFailed(error);
else
this.$refs.child.paramAdded(p);
}
},
template: `<div class="parent"><p>Here is parent ONE:</p><child-component ref="child" #submit="onChildSubmit"></child-component></div>`
});
Vue.component('parent-component2', {
props: { param2: { type: String, required: true } },
methods: {
onChildSubmit(p) {
// Here is a different logic to save the param. In prictice it is gonna be different requests to the server.
var error = SaveParent2({ form: { p: p, param2: this.param2 } });
if (error)
this.$refs.child.paramFailed(error);
else
this.$refs.child.paramAdded(p);
}
},
template: `<div class="parent"><p>Here is parent TWO:</p><child-component ref="child" #submit="onChildSubmit"></child-component></div>`
});
Vue.component('child-component', {
data() {
return {
currentParam: "",
allParams: [],
errorMessage: ""
}
},
methods: {
submit() {
this.errorMessage = "";
this.$emit('submit', this.currentParam);
},
paramAdded(p) {
this.currentParam = "";
this.allParams.push(p);
},
paramFailed(msg) {
this.errorMessage = msg;
}
},
template: `<div><ol><li v-for="p in allParams">{{p}}</li></ol><label>Add Param: <input v-model="currentParam"></label><button #click="submit" :disabled="!currentParam">Submit</button><p class="error">{{errorMessage}}</p></div>`
});
function SaveParent1(data) {
// Axios API to save data. Bellow is a simulation.
if (Math.random() > 0.5)
return null;
else
return 'Parent1: You are not lucky today';
}
function SaveParent2(data) {
// Axios API to save data. Bellow is a simulation.
if (Math.random() > 0.5)
return null;
else
return 'Parent2: You are not lucky today';
}
new Vue({
el: "#app"
});
There is also a live demo available: https://jsfiddle.net/FairKing/novdmcxp/
Architecturally I recommend having a service that is completely abstract from the component hierarchy and that you can inject and use in each of the components. With this kind of component hierarchy and architecture it is easy to run into these issues. It is important to abstract as much functionality and business logic from the components as possible. I think of components in these modern frameworks just merely as HTML templates on steroids, which should at most act as controllers, keeping them as dumb and as thin as possible so that you don't run into these situations. I do not know vue.js so I cannot give you the technical solution but hope this indication helps
I think I have found a solution. So no two ways communication. I can just pass a method and the child will do everything without communicating with parent. I am happy with that I am marking it as an answer. Thanks everyone for your help.
Let me please know what do you think guys.
Bellow is my solution:
<div id="app">
<h2>😀Advanced Parent-Child Communication:</h2>
<parent-component1 param1="ABC"></parent-component1>
<parent-component2 param2="XYZ"></parent-component2>
</div>
Vue.component('parent-component1', {
props: { param1: { type: String, required: true } },
computed: {
saveFunc() {
return function(p) { SaveParent1({ form: { p: p, param1: this.param1 } }); }.bind(this);
}
},
template: `<div class="parent"><p>Here is parent ONE:</p><child-component :saveFunc="saveFunc"></child-component></div>`
});
Vue.component('parent-component2', {
props: { param2: { type: String, required: true } },
computed: {
saveFunc() {
return function(p) { SaveParent2({ form: { p: p, param2: this.param2 } }); }.bind(this);
}
},
template: `<div class="parent"><p>Here is parent TWO:</p><child-component :saveFunc="saveFunc"></child-component></div>`
});
Vue.component('child-component', {
props: {
saveFunc: { type: Function, required: true }, // This is gonna be a Promise in real life.
},
data() {
return {
currentParam: "",
allParams: [],
errorMessage: ""
}
},
methods: {
submit() {
this.errorMessage = "";
var error = this.saveFunc(this.currentParam);
if (error)
this.paramFailed(error);
else
this.paramAdded(this.currentParam);
},
paramAdded(p) {
this.currentParam = "";
this.allParams.push(p);
},
paramFailed(msg) {
this.errorMessage = msg;
}
},
template: `<div><ol><li v-for="p in allParams">{{p}}</li></ol><label>Add Param: <input v-model="currentParam"></label><button #click="submit" :disabled="!currentParam">Submit</button><p class="error">{{errorMessage}}</p></div>`
});
function SaveParent1(data) {
console.log(data);
// Axios API to save data
if (Math.random() > 0.5)
return null;
else
return 'Parent1: You are not lucky today';
}
function SaveParent2(data) {
console.log(data);
// Axios API to save data
if (Math.random() > 0.5)
return null;
else
return 'Parent2: You are not lucky today';
}
new Vue({
el: "#app"
});
The demo link: https://jsfiddle.net/FairKing/novdmcxp/126/
I need to make a pagination in my task, but it is not working.
I made two buttons to which I attached the "click" event and I registered a property in the "data". When I click on the buttons, the property changes and is written to the link and in the same way changes the current 10 posts to the following.
But for some reason it does not work as it should work. Can someone please explain what my mistake is and if you can suggest some articles on the subject of "pagination".
This is my html:
<button type="button" #click="counter -=1" class="prev">Prev</button>
<div class="counter">{{ counter }}</div>
<button type="button" #click="counter +=1" class="next">Next</button>
This is my Vue:
export default {
name: 'app',
data () {
return {
counter: 1,
zero: 0,
posts: [],
createTitle: '',
createBody: '',
visiblePostID: ''
};
},
created () {
axios.get('http://jsonplaceholder.typicode.com/posts?_start=${this.counter}+${this.zero}&_limit=10').then(response => {
this.posts = response.data;
});
}
};
The created method is called only when the component is created. To make the GET request everytime the counter increase or decrease use watches link.
Your example will become:
export default {
name: 'app',
data () {
return {
counter: 1,
zero: 0,
posts: [],
createTitle: '',
createBody: '',
visiblePostID: '',
}
},
watch: {
counter: function(newValue, oldValue) {
this.getData()
}
}
created(){
this.getData()
},
methods: {
getData() {
axios.get(`http://jsonplaceholder.typicode.com/posts?_start=${this.counter}+${this.zero}&_limit=10`).then(response => {
this.posts = response.data
})
}
}
}
You need to create a watcher for your counter that fires a load method. This way every time your counter changes you'll load in the correct posts for the page in your paginated results.
export default {
name: 'app',
data () {
return{
counter: 1,
...
}
},
created(){
this.loadPosts()
},
watch: {
counter(newVal, oldVal){
this.loadPosts()
}
},
methods: {
loadPosts(){
axios.get('http://jsonplaceholder.typicode.com/posts?_start=${this.counter}+${this.zero}&_limit=10')
.then(response => {
this.posts = response.data
})
}
}
}
Maybe this can help you. https://scotch.io/courses/getting-started-with-vue/vue-events-build-a-counter
I don't know vue, but looks like you need a function to load new data
I've been trying to reproduce the button behavior that I've here, but with a different implementation. Basically, I'm trying to use Vuex instead of vue-i18n.js for internationalization purposes.
I now have the following code block, the purpose of which is to create language states and perform a XMLHttpRequest (for the .json files storing the various translations):
Vue.use(Vuex);
var storelang = new Vuex.Store({
state: {
lang: {}
},
mutations: {
LANG: function (state, ln) {
function loadJSON(callback) {
var xobj = new XMLHttpRequest();
xobj.overrideMimeType("application/json");
xobj.open('GET', '../resources/i18n/' + ln + '.json', true);
xobj.onreadystatechange = function () {
if (xobj.readyState == 4 && xobj.status == "200") {
callback(xobj.responseText);
}
};
xobj.send(null);
}
loadJSON(function (languageJSON) {
state.lang = JSON.parse(languageJSON);
})
},
strict: true
}
});
var mix = Vue.mixin({
computed: {
lang: function () {
return storelang.state.lang;
}
}
});
On my component constructor (created and initialized in the root Vue instance), I've the following:
components: {
lang: {
template: '<button type="button" class="btn btn-info" #click.prevent=activate(lang.code) #click="setActiveLang" v-show="!isActive">{{ lang.code }}</button>',
props: [
'active',
'lang'
],
computed: {
isActive: function() {
return this.lang.code == this.active.code
}
},
methods: {
activate: function(code) {
storelang.dispatch('LANG', code);
},
setActiveLang: function() {
this.active = this.lang;
}
},
ready: function() {
storelang.dispatch('LANG', 'en'); //default language
}
}
}
On my root Vue instance's data object, I've added the following:
langs: [{
code: "en"
}, {
code: "fr"
}, {
code: "pt"
}],
active: {
"code": "pt"
}
And finally, on my html:
<div v-for="lang in langs">
<p>
<lang :lang="lang" :active.sync="active"></lang>
</p>
</div>
I cannot figure out what I'm doing wrong here.
UPDATE
Here's a JsFiddle (I've exchanged the XMLHttpRequest request for json arrays). Also, this is a working example, but the language selector buttons do not hide when the respective language is selected, which is the opposite of what I want. Meaning that, I'm attempting to hide each individual language selector button when the user clicks it and selects the respective language (while showing the other language selector buttons).
The solution involves saving anactive state in the store, in addition to the lang state:
new Vuex.Store({
state: {
active: {},
lang: {}
Adding an ACTIVE mutation:
ACTIVE: function(state, ln) {
var langcode = 'en'
//portuguese
if (ln === 'pt') {
langcode = 'pt'
}
//french
if (ln === 'fr') {
langcode = 'fr'
}
state.active = langcode
}
On the computed properties block, one also needs to add getter functions for the active state and return the langcode that is currently active:
Vue.mixin({
computed: {
lang: function() {
return storelang.state.lang
},
enIsActive: function() {
return storelang.state.active == 'en'
},
frIsActive: function() {
return storelang.state.active == 'fr'
},
ptIsActive: function() {
return storelang.state.active == 'pt'
}
}
})
Then, it is just a question of conditionally displaying each of the buttons on the component template by adding v-show="!enIsActive", v-show="!frIsActive", etc.:
var langBtn = Vue.extend({
template: '<button type="button" class="btn btn-info" #click.prevent=activate("en") v-show="!enIsActive">en</button><button type="button" class="btn btn-info" #click.prevent=activate("pt") v-show="!ptIsActive">pt</button><button type="button" class="btn btn-info" #click.prevent=activate("fr") v-show="!frIsActive">fr</button>',
Finally, on the activate method, adding a new line to change the active state when the user clicks a button:
methods: {
activate: function(x) {
storelang.dispatch('LANG', x)
storelang.dispatch('ACTIVE', x)
}
},
The full working code here.