As title
Vuefire can auto get data from firebase database, but it needs some loading time.
So I want to display some css animation before data being fetched, is there any event can I $watch when it successed
The readyCallback approach in the other answer didn't work for me. I got an error document.onSnapshot is not a function.
Instead, I used the binding approach to set a flag when loading is complete.
<script>
// ...
export default {
data() {
return {
data: [],
loaded: false,
}
},
mounted() {
this.$bind('data', firebase.firestore().collection('someDocRef'))
.then(() => this.loaded = true);
},
}
</script>
Then my template can have conditionally-rendered loading screens:
<template>
<template v-if="!loaded">
<p>Loading...</p>
</template>
<template v-if="loaded">
<!-- Display data here -->
</template>
</template>
You can do this multiple ways.
Vuefire has readyCallback out of the box which is callback called when the data is fetched (ready).
Here it is:
var vm = new Vue({
el: '#demo',
data: function() {
return {
loaded: false
}
}
firebase: {
// simple syntax, bind as an array by default
anArray: db.ref('url/to/my/collection'),
// can also bind to a query
// anArray: db.ref('url/to/my/collection').limitToLast(25)
// full syntax
anObject: {
source: db.ref('url/to/my/object'),
// optionally bind as an object
asObject: true,
// optionally provide the cancelCallback
cancelCallback: function () {},
// this is called once the data has been retrieved from firebase
readyCallback: function () {
this.loaded = true // NOTE THIS LINE
}
}
}
})
Related
Following code, is a very simple Firebase - VueJS app, (codeSandBox demo)
app.vue
<template>
<div class="container">
<!-- Adding Quote -->
<add-quote/>
<!-- Display Quotes -->
<quote-list/>
</div>
</template>
<script>
import addQuote from "./components/AddQuote.vue";
import quoteList from "./components/QuoteList.vue";
export default {
components: {
addQuote,
quoteList
},
methods: {
get_allQuotes: function() {
// var vm = this;
var localArr = [];
quotesRef
.once("value", function(snapshot) {
snapshot.forEach(function(snap) {
localArr.push({
key: snap.key,
category: snap.val().category,
quoteTxt: snap.val().quoteTxt
});
});
})
.then(data => {
this.$store.commit("set_allQuotes", localArr);
});
}
},
mounted() {
this.get_allQuotes();
console.log("App: mounted fired");
}
};
</script>
store.js(vuex store)
import Vue from "vue";
import Vuex from "vuex";
Vue.use(Vuex);
export const store = new Vuex.Store({
state: {
quotesList: []
},
getters: {
get_quotesList(state) {
return state.quotesList;
}
},
mutations: {
set_allQuotes(state, value) {
state.quotesList = value;
}
}
});
AddQuote.vue
<template>
<div class="row quote-edit-wrapper">
<div class="col-xs-6">
<textarea v-model.lazy="newQuoteTxt"
rows="4"
cols="50"></textarea>
<button #click="addQuote">Add Quote</button>
</div>
</div>
</template>
<script>
export default {
data() {
return {
newQuoteTxt: '',
}
},
computed: {
allQuotes() {
return this.$store.getters.get_quotesList;
},
newQuoteIdx() {
var localArr = [...this.allQuotes]
if(localArr.length > 0) {
var highestKEY, currKEY
localArr.forEach((element, idx) => {
currKEY = parseInt(element.key)
if(idx == 0) {
highestKEY = currKEY
} else {
if(highestKEY < currKEY) {
highestKEY = currKEY
}
}
})
return highestKEY + 1
} else {
return 1
}
}
},
methods: {
// ADD new Quote in DB
addQuote: function() {
var vm = this
var localArr = [...this.allQuotes]
//1. First attach 'value' event listener,
// Snapshot will contain data from that ref
// when any child node is added/updated/delete
quotesRef.on('value', function (snapshot) {
snapshot.forEach(function(snap) {
var itemExists = localArr.some(function (item, idx) {
return item.key == snap.key
})
// If newly added item doesn't yet exists then add to local array
if (!(itemExists)) {
localArr.push({
key: snap.key,
category: snap.val().category,
quoteTxt: snap.val().quoteTxt })
vm.$store.commit('set_allQuotes', localArr)
}
})
})
//2. Second set/create a new quotes in Firebase,
// When this quote gets added in Firebase,
// value event (attached earlier) gets fired
// with
var newQuoteRef = quotesRef.child(this.newQuoteIdx)
newQuoteRef.set({
category: 'motivation',
quoteTxt: this.newQuoteTxt
})
}
}
}
</script>
quoteList.vue
<template>
<div class="row">
<div class="col-xs-12 quotes-list-wrapper">
<template v-for="(quote,idx) in allQuotes">
<!-- Quote block -->
<div class="quote-block-item">
<p class="quote-txt"> {{quote.quoteTxt}} </p>
</div>
</template>
</div>
</div>
</template>
<script>
export default {
computed: {
allQuotes() {
return this.$store.getters.get_quotesList;
}
}
}
</script>
Note: The main code of concern is of addQuote.vue
User enter newQuoteTxt that gets added to Firebase (addQuote()) as a quote item under quotesRef. As soon as quote is added (on firebase), Firebase client side SDK's value event fires, and adds the new quote (via callback) to localArray (allQuotes). VueJS then updates the DOM with newly added Quote.
The addQuote() method works in the following manner:
First, attach a callback/listener to 'value' event on quotesRef
quotesRef.on('value', function (snapshot) {
....
})
Next, A firebase ref (child of quotesRef) is created with a ID this.newQuoteIdx
var newQuoteRef = quotesRef.child(this.newQuoteIdx)
Then set() is called (on this newly created Ref) adding newquote to firebase RealTime DB.
value event gets triggered (attached from step 1) and listener /callback is called.
The callback looks for this new quote's key in existing list of items by matching keys of localArr and snap.key, if not found, adds the newly quote to localArr. localArr commits to a vuex store.
`vm.$store.commit('set_allQuotes', localArr)`
VueX then updates all subscriber component of this array. VueJS then adds the new quote to the existing list of quotes (updates the DOM)
While debugging the addQuote method, the problem I notice, the execution/flow of script (via F8 in chrome debugger) first steps into the listener/callback attached to value event before the code newQuoteRef.set({ ... }) that adds new quote (on firebase), which in turn will cause 'value' event to trigger.
I am not sure why this occurs. Can anybuddy explain why the listener/callback is called before the quotes is created.
Are child nodes (of QuotesRef) are cached at clientside such that 'value' fires even before new quote is added.
Thanks
If I correctly understand your question (Your code is not extremely easy to follow! :-)) it is the normal behaviour. As explained in the documentation:
The value event will trigger once with the initial data stored at
this location, and then trigger again each time the data
changes.
Your sandbox demo does not actually shows how the app works, but normally you should not set-up the listener in the method that saves a new node to the database. These two things should be decoupled.
One common approach is to set the listener in the created hook of a component (see https://v2.vuejs.org/v2/guide/instance.html#Instance-Lifecycle-Hooks and https://v2.vuejs.org/v2/api/#created) and then in your addQuote method you just write to the database. As soon as you write, the listener will be fired.
I'm pretty new on Vue JS and dbs like Firebase and I'm having some trouble with what I'd like to do.
Here is the idea: I have repeated components ('LaundryMachine.vue') which each have a boolean property (computed property) available.
I want users to be able to change the state of these components. The change is sent to the Firestore DB and the app needs to read the data from the DB.
I have been able link the VueJS code and the DB and edit the DB data within the app. I have however not been successful at reading the data from the DB.
More precisely, I have only been able to read the data from one or several documents of the DB and log at the console. But i can't manage to link the data to properties.
Here is what I have on the LaundryMachine.vue:
<template>
<div class="about">
<h2>Machine {{ this.machineNum }}</h2>
<img src="../assets/washing_machine.png" /><br />
<v-btn v-bind:color="buttonColor" v-on:click="changeAvailability">
{{ this.availability }}</v-btn
>
<v-btn v-bind:color="buttonColor" v-on:click="editState">Edit state</v-btn>
</div>
</template>
<script>
import db from './firebaseInit.js';
export default {
name: 'LaundryMachine',
props: {
name: String,
machineNum: Number,
residenceNum: Number,
},
methods: {
editState: function(event) {
console.log('available:' + this.available);
// Emit to parent component which succesfully edits the fields in the DB
this.$emit('update-availability', this.machineNum, this.residenceNum);
// This part is just about logging out on the console the db documents data which works fine
db.collection('Machines')
.get()
.then(querySnapshot => {
querySnapshot.forEach(doc => {
console.log(doc.id + doc.data() + doc.data().available);
});
});
}
},
computed: {
available: function() {
// This is where I want to link my computed property to the db document field but which doesn't work. If i print {{this.available}}, i'll get an undefined
let ref = db
.collection('Machines')
.doc('machine' + this.residenceNum + this.machineNum);
ref.get().then(snapshot => {
if (snapshot.exists) {
ref.get().then(snapshot => {
return snapshot.data().available;
});
} else {
return true;
}
});
},
availability: function() {
if (this.available) {
return 'disponible';
} else {
return 'indisponible';
}
},
buttonColor: function() {
if (this.available) {
return 'primary';
} else {
return 'red';
}
}
}
};
</script>
This is honestly really frustrating as I'm able to log on the console the fields of the data base but I can't link them to my "available" computed property. I've looked through a lot of posts and firestore doc and I can't find something which works.
Thanks in advance !
I am storing relative paths to images in my firebase database for each item I wish to display. I am having trouble getting the images to appear on the screen, as I need to get the images asynchronously. The firebase schema is currently as follows:
{
items: {
<id#1>: {
image_loc: ...,
},
<id#2>: {
image_loc: ...,
},
}
}
I would like to display each of these images on my page with code such as:
<div v-for="item in items">
<img v-bind:src="item.image_loc">
</div>
This does not work, as my relative location points to a place in firebase storage. The relavent code to get the true url from this relative url is:
firebase.storage().ref('items').child(<the_image_loc>).getDownloadURL()
which returns a promise with the true url. Here is my current vue.js code:
var vue = new Vue({
el: '.barba-container',
data: {
items: []
},
firebase: function() {
return {
items: firebase.database().ref().child('items'),
};
}
});
I have tried using computed properties, including the use of vue-async-computed, but these solutions do not seem to work as I cannot pass in parameters.
Basically, how do I display a list of elements where each element needs the result of a promise?
I was able to solve this by using the asyncComputed library for vue.js and by making a promise to download all images at once, instead of trying to do so individually.
/**
* Returns a promise that resolves when an item has all async properties set
*/
function VotingItem(item) {
var promise = new Promise(function(resolve, reject) {
item.short_description = item.description.slice(0, 140).concat('...');
if (item.image_loc === undefined) {
resolve(item);
}
firebase.storage().ref("items").child(item.image_loc).getDownloadURL()
.then(function(url) {
item.image_url = url;
resolve(item);
})
.catch(function(error) {
item.image_url = "https://placeholdit.imgix.net/~text?txtsize=33&txt=350%C3%97150&w=350&h=150";
resolve(item);
});
});
return promise;
}
var vue = new Vue({
el: '.barba-container',
data: {
items: [],
is_loading: false
},
firebase: function() {
return {
items: firebase.database().ref().child('items'),
};
},
asyncComputed: {
processedItems: {
get: function() {
var promises = this.items.map(VotingItem);
return Promise.all(promises);
},
default: []
}
}
});
Lastly, I needed to use: v-for="item in processedItems" in my template to render the items with image urls attached
I was able to solve it without any extra dependencies not adding elements to the array until the url is resolved:
in my template:
<div v-for="foo in foos" :key="foo.bar">
<img :src="foo.src" :alt="foo.anotherbar">
...
</div>
in my component (for example inside mounted())
const db = firebase.firestore()
const storage = firebase.storage().ref()
const _this = this
db.collection('foos').get().then((querySnapshot) => {
const foos = []
querySnapshot.forEach((doc) => {
foos.push(doc.data())
})
return Promise.all(foos.map(foo => {
return storage.child(foo.imagePath).getDownloadURL().then(url => {
foo.src = url
_this.foos.push(foo)
})
}))
}).then(() => {
console.log('all loaded')
})
I'm trying to make a Meteor helper non-reactive with this code:
let titleNonReactive;
Template.articleSubmission.onCreated(function () {
this.autorun(function() {
titleNonReactive = Template.currentData().title;
});
});
Template.articleSubmission.helpers({
titleNonreactive: function() {
return titleNonReactive;
}
});
However the resulting output is still reactive. If I save a new value in the background, it's automatically updated on the frontend where I'm displaying the result of this helper with {{ titleNonreactive }}.
How can I fix this?
This is likely caused by your Blaze data context (will need to see your Template code to confirm), but here's a possible solution that doesn't involve using Tracker.nonreactive. Since you want the value of titleNonreactive to not be reactive, you can just use a standard local / non-reactive variable to store a copy of the original reactive title. For example:
import { Template } from 'meteor/templating';
import { articles } from '/imports/api/articles/collection';
import './main.html';
let originalTitle;
Template.body.onCreated(function onCreated() {
this.autorun(() => {
const article = articles.findOne();
if (article && !originalTitle) {
originalTitle = article.title;
}
});
});
Template.body.helpers({
article() {
return articles.findOne();
},
titleNonreactive() {
return originalTitle;
}
});
Then in your Template:
<ul>
{{#with article}}
<li>Reactive Title: {{title}}</li>
<li>Non-Reactive Title: {{titleNonreactive}}</li>
{{/with}}
</ul>
Session.set('coursesReady', false); on startup.
UPDATE:
I made it into a simpler problem. Consider the following code.
Inside router.js
Router.route('/', function () {
Meteor.subscribe("courses", function() {
console.log("data ready")
Session.set("coursesReady", true);
});
}
and inside main template Main.js
Template.Main.rendered = function() {
if (Session.get('coursesReady')) {
console.log("inject success");
Meteor.typeahead.inject();
}
The message "inject success" is not printed after "data ready" is printed. How come reactivity does not work here?
Reactivity "didn't work" because rendered only executes once (it isn't reactive). You'd need to wrap your session checks inside of a template autorun in order for them to get reevaluated:
Template.Main.rendered = function() {
this.autorun(function() {
if (Session.get('coursesReady')) {
console.log("inject success");
Meteor.typeahead.inject();
}
});
};
Probably a better solution is to wait on the subscription if you want to ensure your data is loaded prior to rendering the template.
Router.route('/', {
// this template will be rendered until the subscriptions are ready
loadingTemplate: 'loading',
waitOn: function () {
// return one handle, a function, or an array
return Meteor.subscribe('courses');
},
action: function () {
this.render('Main');
}
});
And now your rendered can just do this:
Template.Main.rendered = function() {
Meteor.typeahead.inject();
};
Don't forget to add a loading template.
To Solve Your Problem
Template.registerHelper("course_data", function() {
console.log("course_data helper is called");
if (Session.get('coursesReady')) {
var courses = Courses.find().fetch();
var result = [ { **Changed**
name: 'course-info1',
valueKey: 'titleLong',
local: function() {
return Courses.find().fetch();
},
template: 'Course'
}];
Session.set('courseResult', result); **New line**
return Session.get('courseResult'); **New line**
,
Explanation
The answer is at the return of the helper function needs to have be associated with reactivity in order for Blaze, template renderer, to know when to rerender.
Non-reactive (Doesn't change in the DOM as values changes)
Template.Main.helpers({
course_data: UI._globalHelpers.course_data ** Not reactive
});
Essentially: UI._globalHelpers.course_data returns an array of objects which is not reactive:
return [
{
name: 'course-info1',
valueKey: 'titleLong',
local: function() {
return Courses.find().fetch();
},
template: 'Course'
},
Reactive
From Meteor Documentation:
http://docs.meteor.com/#/full/template_helpers
Template.myTemplate.helpers({
foo: function () {
return Session.get("foo"); ** Reactive
}
});
Returning Session.get function to Blaze is reactive; thus, the template will change as the values changes.