I'm doing something like this:
import { observable, action } from 'mobx';
export default class DataStore {
#observable pageData:object
#action fetch() {
superagent.get(url1)
.send('got url 1', action((err, results) => {
if (err)
return;
this.pageData = this.pageData || {};
this.pageData.urlData1 = results;
this.fetchAnother();
}));
}
#action fetchAnother() {
superagent.get(url2)
.send('got url 2', action((err, results) => {
if (err)
return;
this.pageData = this.pageData || {};
this.pageData.urlData2 = results;
}));
}
}
These actions are separate because sometimes fetchAnother is called by itself.
I inject the store into my React component class. When fetch is called, the first async callback wrapped in action updates the page, and urlData1 is rendered. Then the 2nd callback in fetchAnother is called and executes, but does not render, and urlData2 will only show if I force a re-render in some other way. Why, and how can I fix that?
MobX doesn't support dynamically adding fields to plain objects. Either use an observable map or initialize the fields upfront:
pageData = { urlData1: null, urlData2: null }
Related
I joined a big/medium project, I am having a hard time creating my first redux-saga-action things, it is going to be a lot of code since they are creating a lot of files to make things readable.
So I call my action in my componentDidMount, the action is being called because I have the alert :
export const fetchDataRequest = () => {
alert("actions data");
return ({
type: FETCH_DATA_REQUEST
})
};
export const fetchDataSuccess = data => ({
type: FETCH_DATA_SUCCESS,
payload: {
data,
},
});
This is my history saga : ( when I call the action with this type, The function get executed )
export default function* dataSaga() {
// their takeEverymethods
yield takeEvery(FETCH_DATA_REQUEST, fetchData);
}
This is what has to be called : ( I am trying to fill my state with data in a json file : mock )
export default function* fetchTronconsOfCircuit() {
try {
// Cal to api
const client = yield call(RedClient);
const data = yield call(client.fetchSomething);
// mock
const history = data === "" ? "" : fakeDataFromMock;
console.log("history : ");
console.log(history);
if (isNilOrEmpty(history)) return null;
yield put(fetchDataSuccess({ data: history }));
} catch (e) {
yield put(addErr(e));
}
}
And this is my root root saga :
export default function* sagas() {
// many other spawn(somethingSaga);
yield spawn(historySaga);
}
and here is the reducer :
const fetchDataSuccess = curry(({ data }, state) => ({
...state,
myData: data,
}));
const HistoryReducer = createSwitchReducer(initialState, [
[FETCH_DATA_SUCCESS, fetchDataSuccess],
]);
The method createSwitchReducer is a method created by the team to create easily a reducer instead of creating a switch and passing the action.type in params etc, their method is working fine, and I did exactly what they do for others.
Am I missing something ?
I feel like I did everything right but the saga is not called, which means it is trivial problem, the connection between action and saga is a common problem I just could not figure where is my problem.
I do not see the console.log message in the console, I added an alert before the try-catch but got nothing too, but alert inside action is being called.
Any help would be really really appreciated.
yield takeEvery(FETCH_DATA_REQUEST, fetchData);
should be
yield takeEvery(FETCH_DATA_REQUEST, fetchTronconsOfCircuit);
I have a Vue.js SPA with some pages that display data from a backend. When I navigate the pages via the navbar, everything works fine, components and data are loaded.
When I'm on the page, e.g. localhost:8080/#/mypage and press F5, the data doesn't get loaded / rendered. Same goes for when I directly navigate to the page via the address bar.
The data gets loaded in this function:
async beforeMount() {
await this.initializeData();
}
I've tried to call the method in every lifecycle hook, i.e. created, beforeCreated, mounted etc...
In the mounted lifecycle hook I'm setting a boolean property to true, so that the table is only rendered when the component is loaded (done with v-if).
mounted() {
this.componentLoaded = true;
}
Not sure if this is important, but I've tried it with or without and it doesn't work.
I would really appreciate it if somebody knew whats happening here.
EDIT:
this.applications is a prop and contains multiple applications which contain instances. I want to add some variables from the backend to each application.
console.log(1) gets printed
console.log(2) does not
initializeData: function () {
let warn = 0;
console.log("1");
this.applications.forEach(async application => {
const instance = application.instances[0];
console.log("2");
let myData = null;
try {
const response = await instance.axios.get('url/myData');
myData = response.data;
} catch (err) {
}
let tmpCount = 0;
let tmpFulfilled = 0;
myData.forEach(ba => {
if(!ba.fulfilled){
warn++;
application.baAllFulfilled = false;
}else {
tmpFulfilled++;
}
tmpCount++;
})
console.log("3");
// Assign values
this.baTotalWarnings = warn;
application.baAnzahl = tmpCount;
application.baFulfilled = tmpFulfilled;
this.componentLoaded = true;
}
Try removing the async and await keywords from your beforeMount, and remove this.componentLoaded from mounted. Set it instead in the then block (or after await) in your initializeData method. I'm not sure Vue supports the async keyword in its lifecycle methods.
Something like this:
beforeMount() {
this.initializeData(); // start processing the method
}
methods: {
initializeData() {
callToBackend().then(() => {
this.componentLoaded = true // backend call ready, can now show the table
})
}
}
I'm building a React Native app and when one button is pressed I want to call two functions. The first one will make a get call and set the state loading: true, the second one will show a popup with the result of that get call.
I am calling the second function only if loading === false but it is executed immediately after the first one before the state can change, because loading is false by default. I can resolve this with setTimeout but I was wondering if there was a cleaner way to do this.
onPress() {
this.props.getUsers();
setTimeout(() => {
if (this.props.loading === false) {
this.props.popUpVisible();
}
}, 1000);
}
You can create callback function for that
getUsers = (callback) => {
//do whatever you want
//when it's done
callback();
}
In onPress function
onPress = () => {
this.props.getUsers(() => {
if (this.props.loading === false) {
this.props.popUpVisible();
}
});
}
setState Function can take two param:
setState(updater, callback)
setState({loading:true},() => {
//this fires once state.loading === true
})
Use getDerivedStateFromProps. It always fire when component's props change.
Below is the example.
class EmailInput extends Component {
state = {
email: this.props.defaultEmail,
prevPropsUserID: this.props.userID
};
static getDerivedStateFromProps(props, state) {
// Any time the current user changes,
// Reset any parts of state that are tied to that user.
// In this simple example, that's just the email.
if (props.userID !== state.prevPropsUserID) {
return {
prevPropsUserID: props.userID,
email: props.defaultEmail
};
}
return null;
}
// ...
}
I'm trying to render my DOM, dependent on some data I'm returning from an axios get. I can't seem to get the timing right. The get is in the created hook, but there is a delay between the get and actually receiving the data. Basically if there is info in seller_id then I need to show the cancel button, otherwise don't. Here is my code:
this is in my created hook
axios.get('https://bc-ship.c9users.io/return_credentials').then(response => {
this.seller_id = response.data.seller_id;
this.selected_marketplace = response.data.marketplace;
this.token = response.data.auth_token;
});
and then this is the logic to show or hide the button. I've tried created, mounted, beforeUpdate, and updated all with no luck. I've also tried $nextTick but I can't get the timing correct. This is what I have currently:
beforeUpdate: function () {
// this.$nextTick(function () {
function sellerIdNotBlank() {
var valid = this.seller_id == '';
return !valid;
}
if(sellerIdNotBlank()){
this.show_cancel_button = true;
}
// })
},
First, it is pointless to get your data from backend and try to sync with Vue.js lifecycle methods. It never works.
Also, you should avoid beforeUpdate lifecycle event. It is often a code smell. beforeUpdate is to be used only when you have some DOM manipulations done manually and you need to adjust them again before Vue.js attempt to re-render.
Further, show_cancel_button is a very good candidate for a computed property. Here is how component will look:
const componentOpts = {
data() {
return {
seller_id: '',
// ... some more fields
};
},
created() {
axios.get('https://bc-ship.c9users.io/return_credentials').then(response => {
this.seller_id = response.data.seller_id;
this.selected_marketplace = response.data.marketplace;
this.token = response.data.auth_token;
});
},
computed: {
show_cancel_button() {
return this.seller_id !== '';
}
}
}
I have a basic component that calls a webservice during the componentDidMount phase and overwrites the contents value in my state:
import React, {Component} from 'react';
import {Text} from "react-native";
class Widget extends Component {
constructor() {
super();
this.state = {
contents: 'Loading...'
}
}
async componentDidMount() {
this.setState(...this.state, {
contents: await this.getSomeContent()
});
}
render() {
return (
<Text>{this.state.contents}</Text>
)
}
async getSomeContent() {
try {
return await (await fetch("http://someurl.com")).text()
} catch (error) {
return "There was an error";
}
}
}
export default Widget;
I would like to use Jest snapshots to capture the state of my component in each one of the following scenarios:
Loading
Success
Error
The problem is that I have to introduce flaky pausing to validate the state of the component.
For example, to see the success state, you must place a small pause after rendering the component to give the setState method a chance to catch up:
test('loading state', async () => {
fetchMock.get('*', 'Some Content');
let widget = renderer.create(<Widget />);
// --- Pause Here ---
await new Promise(resolve => setTimeout(resolve, 100));
expect(widget.toJSON()).toMatchSnapshot();
});
I'm looking for the best way to overcome the asynchronicity in my test cases so that I can properly validate the snapshot of each state.
If you move the asynchronous call out of setState, you can delay setState until the network call has resolved. Then you can use setState's optional callback (which fires after the state change) to capture the state.
So, something like this:
async componentDidMount() {
var result = await this.getSomeContent()
this.setState(...this.state, {
contents: result
},
// setState callback- fires when state changes are complete.
()=>expect(this.toJSON()).toMatchSnapshot()
);
}
UPDATE:
If you want to specify the validation outside of the component, you could create a prop, say, stateValidation to pass in a the validation function:
jest('loading state', async () => {
fetchMock.get('*', 'Some Content');
jestValidation = () => expect(widget.toJSON()).toMatchSnapshot();
let widget = renderer.create(<Widget stateValidaton={jestValidation}/>);
});
then use the prop in the component:
async componentDidMount() {
var result = await this.getSomeContent()
this.setState(...this.state, {
contents: result
},
// setState callback- fires when state changes are complete.
this.props.stateValidaton
);
}