I have a component that must make an HTTP request based off new props. Currently it's taking a while to actually update, so we've implemented a local store that we'd like to use to show data from past requests and then show the HTTP results once they actually arrive.
I'm running into issues with this strategy:
componentWillRecieveProps(nextProps){
this.setState({data:this.getDataFromLocalStore(nextProps.dataToGet)});
this.setState({data:this.makeHttpRequest(nextProps.dataToGet)});
//triggers single render, only after request gets back
}
What I think is happening is that react bundles all the setstates for each lifecycle method, so it's not triggering render until the request actually comes back.
My next strategy was this:
componentWillRecieveProps(nextProps){
this.setState({data:this.getDataFromLocalStore(nextProps.dataToGet)});
this.go=true;
}
componentDidUpdate(){
if(this.go){
this.setState({data:this.makeHttpRequest(this.props.dataToGet)});
}
this.go=false;
}
//triggers two renders, but only draws 2nd, after request gets back
This one SHOULD work, it's actually calling render with the localstore data immediately, and then calling it again when the request gets back with the request data, but the first render isnt actually drawing anything to the screen!
It looks like react waits to draw the real dom until after componentDidUpdate completes, which tbh, seems completely against the point to me.
Is there a much better strategy that I could be using to achieve this?
Thanks!
One strategy could be to load the data using fetch, and calling setState when the data has been loaded with the use of promises.
componentWillRecieveProps(nextProps){
this.loadData(nextProps)
}
loadData(nextProps){
// Create a request based on nextProps
fetch(request)
.then(response => response.json())
.then(json => this.setState({updatedValue: json.value})
}
I use the pattern bellow all the time (assuming your request function supports promises)
const defaultData = { /* whatever */ }
let YourComponent = React.createClass({
componentWillRecieveProps: function(nextProps) {
const that = this
const cachedData = this.getDataFromLocalStore(nextProps)
that.setState({
theData: { loading: true, data: cachedData }
})
request(nextProps)
.then(function(res) {
that.setState({
theData: { loaded: true, data: res }
})
})
.catch(function() {
that.setState({
theData: { laodingFailed: true }
})
})
},
getInitialState: function() {
return {
theData: { loading: true, data: defaultData }
};
},
render: function() {
const theData = this.state.theData
if(theData.loading) { return (<div>loading</div>) } // you can display the cached data here
if(theData.loadingFailed) { return (<div>error</div>) }
if(!theData.loaded) { throw new Error("Oups") }
return <div>{ theData.data }</div>
}
)}
More information about the lifecycle of components here
By the way, you may think of using a centralized redux state instead of the component state.
Also my guess is that your example is not working because of this line:
this.setState({data:this.makeHttpRequest(this.props.dataToGet)});
It is very likely that makeHttpRequest is asynchronous and returns undefined. In other words you are setting your data to undefined and never get the result of the request...
Edit: about firebase
It looks like you are using firebase. If you use it using the on functions, your makeHttpRequest must look like:
function(makeHttpRequest) {
return new Promise(function(resolve, reject) {
firebaseRef.on('value', function(data) {
resolve(data)
})
})
}
This other question might also help
Related
I'm working on a project with Vue-CLI, and here's some parts of my code;
//vuex
const member = {
namespaced:true,
state:{
data:[]
},
actions:{
getAll:function(context,apiPath){
axios.post(`http://localhost:8080/api/yoshi/backend/${apiPath}`, {
action: "fetchall",
page: "member",
})
.then(function(response){
context.commit('displayAPI', response.data);
});
},
toggle:(context,args) => {
return axios
.post(`http://localhost:8080/api/yoshi/backend/${args.address}`,
{
action:"toggle",
ToDo:args.act,
MemberID:args.id
})
.then(()=>{
alert('success');
})
},
},
mutations:{
displayAPI(state, data){
state.tableData = data;
},
},
getters:{
getTableData(state){
return state.tableData
}
}
}
//refresh function in member_management.vue
methods: {
refresh:function(){
this.$store.dispatch('member/getAll',this.displayAPI);
this.AllDatas = this.$store.getters['member/getTableData'];
}
}
//toggle function in acc_toggler.vue
ToggleAcc: function (togg) {
let sure = confirm(` ${todo} ${this.MemberName}'s account ?`);
if (sure) {
this.$store
.dispatch("member/toggle", {
address: this.displayAPI,
id: this.MemberID,
act: togg,
Member: this.MemberName,
})
.then(() => {
this.$emit("refresh");
});
}
},
The acc_toggler.vue is a component of member_management.vue, what I'm trying to do is when ToggleAcc() is triggered, it emits refresh() and it requests the updated data.
The problem is , after the whole process, the data is updated (I checked the database) but the refresh() funciton returns the data that hadn't be updated, I need to refresh the page maybe a couple of times to get the updated data(refresh() runs everytime when created in member_management.vue)
Theoretically, the ToggleAcc function updates the data, the refresh() function gets the updated data, and I tested a couple of times to make sure the order of executions of the functions are right.
However, the situation never changes. Any help is appreciated!
The code ignores promise control flow. All promises that are supposed to be awited, should be chained. When used inside functions, promises should be returned for further chaining.
It is:
refresh:function(){
return this.$store.dispatch('member/getAll',this.displayAPI)
.then(() => {
this.AllDatas = this.$store.getters['member/getTableData'];
});
}
and
getAll:function(context,apiPath){
return axios.post(...)
...
I'm trying to run a function that needs some data that I get back from the mounted method. Right now I try to use computed to create the function but unfortunately for this situation computed runs before mounted so I don't have the data I need for the function. Here is what I'm working with:
computed: {
league_id () {
return parseInt(this.$route.params.id)
},
current_user_has_team: function() {
debugger;
}
},
mounted () {
const params = {};
axios.get('/api/v1/leagues/' +this.$route.params.id, {
params,
headers: {
Authorization: "Bearer "+localStorage.getItem('token')
}
}).then(response => {
debugger;
this.league = response.data.league
this.current_user_teams = response.data.league
}).catch(error => {
this.$router.push('/not_found')
this.$store.commit("FLASH_MESSAGE", {
message: "League not found",
show: true,
styleClass: "error",
timeOut: 4000
})
})
}
As you can see I have the debugger in the computed function called current_user_has_team function. But I need the data I get back from the axios call. Right now I don't have the data in the debugger. What call back should I use so that I can leverage the data that comes back from the network request? Thank You!
If your computed property current_user_has_team depends on data which is not available until after the axios call, then you need to either:
In the current_user_has_team property, if the data is not available then return a sensible default value.
Do not access current_user_has_team from your template (restrict with v-if) or anywhere else until after the axios call has completed and the data is available.
It's up to you how you want the component to behave in "loading" situations.
If your behavior is synchronous, you can use beforeMount instead of mounted to have the code run before computed properties are calculated.
I am using ember. I intercept one component's button click in controller. The click is to trigger a new report request. When a new report request is made, I want the newly made request to appear on the list of requests that I currently show. How do I make ember refresh the page without obvious flicker?
Here is my sendAction code:
actions: {
sendData: function () {
this.set('showLoading', true);
let data = {
startTime: date.normalizeTimestamp(this.get('startTimestamp')),
endTime: date.normalizeTimestamp(this.get('endTimestamp')),
type: constants.ENTERPRISE.REPORTING_PAYMENT_TYPE
};
api.ajaxPost(`${api.buildV3EnterpriseUrl('reports')}`, data).then(response => {
this.set('showLoading', false);
return response.report;
}).catch(error => {
this.set('showLoading', false);
if (error.status === constants.HTTP_STATUS.GATEWAY_TIMEOUT) {
this.notify.error(this.translate('reports.report_timedout'),
this.translate('reports.report_timedout_desc'));
} else {
this.send('error', error);
}
});
}
There are few think you should consider. Generaly you want to have variable that holds an array which you are render in template in loop. For example: you fetch your initial set of data in route and pass it on as model variable.
// route.js
model() { return []; }
// controller
actions: {
sendData() {
foo().then(payload => {
// important is to use pushObjects method.
// Plain push will work but wont update the template.
this.get('model').pushObjects(payload);
});
}
}
This will automatically update template and add additional items on the list.
Boilerplate for showLoading
You can easily refactor your code and use ember-concurency. Check their docs, afair there is example fitting your usecase.
I am now using react-http-request in my React.js component to send request and process the response. The URL parameter passed is relevant to the component state such that when the state changes, the component will be re-rendered and change the component display.
This works on the first request. However, I found that the component does not return a {load: true} after the second request, and I wonder how to solve this.
I tried to call the onRequest method and set the loading state for the component, but I cannot change the loading state after the request is finished (as render function cannot change the state).
react-http-request: https://github.com/mbasso/react-http-request
My Code is like below:
var FilmList = React.createClass({
getInitialState: function(){
return {
queryType: this.props.queryType
}
},
// ... details emitted.
render: function(){
return (<Request
url={config.url.api + "/" + this.state.queryType}
method="get"
accept="application/json"
query={{ several parameter }}
>
{
({error, result, loading}) => {
if (loading || error) {
return <Loading />
}
else {
// process the result here.
}
}
}
</Request>)
}
So, my initial recommendation would be that you use some state management library (redux, mobx, etc) but it is not necessary to get a working example of your code, so:
import fetch from 'whatwg-fetch'; // gives compatibility with older browsers
var FilmList = React.createClass({
getInitialState: function(){
return {
queryType: this.props.queryType,
content: null
}
},
componentWillMount: function() {
this.fetchContent();
},
fetchContent: function() {
const uri = config.url.api + "/" + this.state.queryType;
// You can use w/e you want here (request.js, etc), but fetch is the latest standard in the js world
fetch(uri, {
method: 'GET',
// More properties as you see fit
})
.then(response => response.json()) // might need to do this ;)
.then(response => {
this.setState({
content: response
})
})
},
// ...
render: function(){
const content = this.state.content? (
// render your content based on this.state.content
): (
<Loading />
)
return content;
}
});
Haven't tested this code, but there are some nice benefits to it:
The http request is not dependant on React, which should (in theory) be for UI components.
The fetching mechanism is decoupled, and can be re-used at any point in the component lifecycle
In my opinion easier to read, divided into smaller logical chunks
I would recommend reading the React Component Lifecycle.
In this case, I read the source code of the react-http-request, and found that there is a weakness that after accepting and sending the second request, the component failed to update the state of "loading" returns.
// starts from Line 49
value: function componentWillReceiveProps(nextProps) {
if (JSON.stringify(this.props) === JSON.stringify(nextProps)) {
return;
}
this.request.abort();
this.performRequest(nextProps);
}
Manually changed the state of loading here can help reset the loading after each request received.
I changed the source code of this lib, and sent the pull request to the repo. It's now merged into master and ejected a new release.
See: https://github.com/mbasso/react-http-request/pull/3
Thus, this problem can be solved by keeping the lib update to the release (currently it is 1.0.3).
I have a "box" route/controller as below;
export default Ember.Controller.extend({
initialized: false,
type: 'P',
status: 'done',
layouts: null,
toggleFltr: null,
gridVals: Ember.computed.alias('model.gridParas'),
gridParas: Ember.computed('myServerPars', function() {
this.set('gridVals.serverParas', this.get('myServerPars'));
this.filterCols();
if (!this.get('initialized')) {
this.toggleProperty('initialized');
} else {
Ember.run.scheduleOnce('afterRender', this, this.refreshBox);
}
return this.get('gridVals');
}),
filterCols: function()
{
this.set('gridVals.layout', this.get('layouts')[this.get('type')]);
},
myServerPars: function() {
// Code to set serverParas
return serverParas;
}.property('type', 'status', 'toggleFltr'),
refreshBox: function(){
// Code to trigger refresh grid
}
});
My route looks like;
export default Ember.Route.extend({
selectedRows: '',
selectedCount: 0,
rawResponse: {},
model: function() {
var compObj = {};
compObj.gridParas = this.get('gridParas');
return compObj;
},
activate: function() {
var self = this;
self.layouts = {};
var someData = {attr1:"I"};
var promise = this.doPost(someData, '/myService1', false); // Sync request (Is there some way I can make this work using "async")
promise.then(function(response) {
// Code to use response & set self.layouts
self.controllerFor(self.routeName).set('layouts', self.layouts);
});
},
gridParas: function() {
var self = this;
var returnObj = {};
returnObj.url = '/myService2';
returnObj.beforeLoadComplete = function(records) {
// Code to use response & set records
return records;
};
return returnObj;
}.property(),
actions: {
}
});
My template looks like
{{my-grid params=this.gridParas elementId='myGrid'}}
My doPost method looks like below;
doPost: function(postData, requestUrl, isAsync){
requestUrl = this.getURL(requestUrl);
isAsync = (isAsync == undefined) ? true : isAsync;
var promise = new Ember.RSVP.Promise(function(resolve, reject) {
return $.ajax({
// settings
}).success(resolve).error(reject);
});
return promise;
}
Given the above setup, I wanted to understand the flow/sequence of execution (i.e. for the different hooks).
I was trying to debug and it kept hopping from one class to another.
Also, 2 specific questions;
I was expecting the "activate" hook to be fired initially, but found out that is not the case. It first executes the "gridParas" hook
i.e. before the "activate" hook. Is it because of "gridParas"
specified in the template ?
When I do this.doPost() for /myService1, it has to be a "sync" request, else the flow of execution changes and I get an error.
Actually I want the code inside filterCols() controller i.e.
this.set('gridVals.layout', this.get('layouts')[this.get('type')]) to
be executed only after the response has been received from
/myService1. However, as of now, I have to use a "sync" request to do
that, otherwise with "async", the execution moves to filterCols() and
since I do not have the response yet, it throws an error.
Just to add, I am using Ember v 2.0
activate() on the route is triggered after the beforeModel, model and afterModel hooks... because those 3 hooks are considered the "validation phase" (which determines if the route will resolve at all). To be clear, this route hook has nothing to do with using gridParas in your template... it has everything to do with callling get('gridParas') within your model hook.
It is not clear to me where doPost() is connected to the rest of your code... however because it is returning a promise object you can tack on a then() which will allow you to essentially wait for the promise response and then use it in the rest of your code.
Simple Example:
this.doPost().then((theResponse) => {
this.doSomethingWith(theResponse);
});
If you can simplify your question to be more clear and concise, i may be able to provide more info
Generally at this level you should explain what you want to archive, and not just ask how it works, because I think you fight a lot against the framework!
But I take this out of your comment.
First, you don't need your doPost method! jQuerys $.ajax returns a thenable, that can be resolved to a Promise with Ember.RSVP.resolve!
Next: If you want to fetch data before actually rendering anything you should do this in the model hook!
I'm not sure if you want to fetch /service1, and then with the response you build a request to /service2, or if you can fetch both services independently and then show your data (your grid?) with the data of both services. So here are both ways:
If you can fetch both services independently do this in your routes model hook:
return Ember.RSVP.hash({
service1: Ember.RSVP.resolve($.ajax(/*your request to /service1 with all data and params, may use query-params!*/).then(data => {
return data; // extract the data you need, may transform the response, etc.
},
service2: Ember.RSVP.resolve($.ajax(/*your request to /service2 with all data and params, may use query-params!*/).then(data => {
return data; // extract the data you need, may transform the response, etc.
},
});
If you need the response of /service1 to fetch /service2 just do this in your model hook:
return Ember.RSVP.resolve($.ajax(/*/service1*/)).then(service1 => {
return Ember.RSVP.resolve($.ajax(/*/service2*/)).then(service2 => {
return {
service1,
service2
}; // this object will then be available as `model` on your controller
});
});
If this does not help you (and I really think this should fix your problems) please describe your Problem.