Update prop for dynamically inserted element - node.js

New to react... Really banging my head against it with this one... I'm trying to figure out how to get a dynamically inserted component to update when the props are changed. I've assigned it to a parent state object but it doesn't seem to re-render. I've read that this is what's supposed to happen.
I was using ReactDOM.unmountComponentAtNode to re-render the specific elements I needed to, but it kept yelling at me with red text.
I need to hide "chat.message" unless the user has the authority to see it (server just sends empty string), but I still need to render the fact that it exists, and reveal it should the user get authentication. I'm using a css transition to reveal it, but I really need a good way to update the chat.message prop easily.
renderChats(uuid){
let userState = this.state.userStates.find(user => {
return user.uuid === uuid;
});
const children = userState.chats.map((chat) => {
let ChatReactElement = this.getChatMarkup(chat.cuid, chat.message, chat.status);
return ChatReactElement;
});
ReactDOM.render(children, document.getElementById(`chats-${this.state.guid}-${uuid}`));
}
getChatMarkup() just returns JSX and inserts Props... I feel like state should be getting passed along here. Even when I use a for-loop and insert the state explicitly, it doesn't seem to re-render on changes.
getChatMarkup(cuid, message, status){
return(
<BasicChatComponent
key={cuid}
cuid={cuid}
message={message}
status={status}
/>
);
}
I attempted to insert some code line this:
renderChats(uuid){
let userState = this.state.userStates.find(user => {
return user.uuid === uuid;
});
const children = userState.chats.map((chat) => {
let ChatReactElement = this.getChatMarkup(chat.cuid, chat.message, chat.status);
if(chat.status.hidden)
this.setState({ hiddenChatRE: [ ...this.state.hiddenChatRE, ChatReactElement ] }); // <== save elements
return ChatReactElement;
});
ReactDOM.render(children, document.getElementById(`chats-${this.state.guid}-${uuid}`));
}
and later in my code:
this.state.hiddenChatRE.every(ReactElement => {
if(ReactElement.key == basicChats[chatIndex].cuid){
ReactElement.props = {
... //completely invalid code
}
}
});
The only response I see here is my ReactDOM.unmountComponentAtNode(); approach...
Can anyone point me in the right direction here?

Although perhaps I should be kicking myself, I read up on how React deals with keys on their components. So there's actually a fairly trivial answer here if anyone comes looking... Just call your render function again after you update the state.
In my case, something like:
this.setState(state =>({
...state,
userStates : state.userStates.map((userstate) => {
if(userstate.uuid == basicChats[chatIndex].uuid) return {
...userstate,
chats: userstate.chats.map((chat) => {
if(chat.cuid == basicChats[chatIndex].cuid){
//
return {
cuid: basicChats[chatIndex].cuid,
message: basicChats[chatIndex].message,
status: basicChats[chatIndex].status
}
}
else return chat;
})
}
else return userstate;
})
}));
and then, elsewhere in my example:
this.state.userStates.map((userstate) => {
this.renderChats(userstate.uuid);
});
Other than the fact that I'd recommend using indexed arrays for this example to cut complexity, this is the solution, and works. This is because even though it feels like you'd end up with duplicates (that was my intuition), the uid on the BasicChatComponent itself makes all the difference, letting react know to only re-render those specific elements.

Related

Dynamic Table updates "too late" ReactJS

my problem is, that I have a table which should update everytime when the user chooses something from a dropdown component. The problem now is that my table updates "too late" in the frontend. So when the user chooses an option for the first time nothing will happen. Then when the user chooses an option for the second time from the dropdown component, the table will show the data from the option he has picked before. If the user chooses an option for the 3rd time, the table will show the data from the second one and so on.
So how can I fix this? I work with ReactJS and Semantic UI
My Code:
This renders the Row for the existing data
renderTableData() {
return this.state.songs.map((song, index) => {
const { id, nr, songname, link } = song
return (
<Table.Row key={id}>
<Table.Cell>{nr}</Table.Cell>
<Table.Cell>{songname}</Table.Cell>
<Table.Cell>{link}</Table.Cell>
</Table.Row>
)
})
}
The Code in the main render() function of React (Its shown correctly, expect that the data is "outdated":
`<Table>
<Table.Header>
<Table.Row>
<Table.HeaderCell width={1}>Nr</Table.HeaderCell>
<Table.HeaderCell width={2}>Songname</Table.HeaderCell>
<Table.HeaderCell width={1}>Link</Table.HeaderCell>
</Table.Row>
</Table.Header>
{this.renderTableData()}
</Table>`
The code when the option from the dropdown gets changed:
onChangeDropdown(e) {
this.setState({game: e.target.textContent}, ()=>{
this.state.songs.length = 0;
for(var i = 0; i< this.state.musicData.length;i++){
if(this.state.musicData[i].game == this.state.game){
for(var j = 0; j<this.state.musicData[i].songs.length;j++){
this.state.songs.push({id: j+1, nr: j+1, songname: this.state.musicData[i].songs[j].name, link: this.state.musicData[i].songs[j].link})
}
break;
}
}
this.renderTableData()
})
}
The game variable in this.setState is correct and also the for-loop works as expected when the user changes the dropdown option, I already checked it with the debugger
I hope you can help me out there, ty
is not that is updating too late, is that you are mutating the state without using setState so React doesn't know what changed, you should refactor your code to always use setState to update the state, not push, something like this:
onChangeDropdown(e) {
this.setState((currentState) => {
const newSongs = [];
const game = e.target.textContent;
musicData.forEach((data) => {
if (data.game === game) {
musicData.songs.forEach((song, index) => {
newSongs.push({
id: index + 1,
nr: index + 1,
songname: song.name,
link: song.link,
});
});
}
});
return {
...currentState,
game,
songs: newSongs,
};
});
}
I changed your for loops to use forEach, less complexity, easier to read
Here is what I did:
create a empty array to store the selected songs (newSongs)
loop all the music data and then loop all the songs inside each item in music data
add the songs from the selected game into newSongs
return newSongs + game to update the selected game, ...currentState is to preserve the other parts of the state between changes
So every time the dropodown changes, I create a new array and run the logic
The setState callback can return an object to replace whole state, so before that you can do any calculation you need to.
Updating the state in React is asyncronous, that's one of the reasons you can't mutate the state directly and need to use setState any time you need to update it

Cypress get text value from an element

I am trying to get a text from an element with Cypress in the first test from the first domain and then type it in the second test in another domain, here is a code
I have to grab code from h4.
I implemented next part of code:
get studentCouponValue() {
return cy.get('h4').then(($span) => {
const couponValue = $span.text();
cy.log(couponValue);
})
}
in logs, I see the correct coupon's value, but when I am trying to type it into the field I get an error
The chain approach doesn't fit my expectation, cause i am going to use it in different tests.
Try this:
get studentCouponValue() {
return cy.get('h4').then(($span) => {
const couponValue = $span.innerText;
cy.log(couponValue);
})
}
i resolved
initStudentCouponValue() {
const self = this;
return cy.get('main > .container-fluid').find('h4').then((span) => {
self.couponValue = span.text();
cy.log('First log '+ self.couponValue);
return new Cypress.Promise((resolve) => {
return resolve(self.couponValue);
});
});
}
getStudentCouponValue() {
return this.couponValue;
}
in the test where we want to use value
let couponValue;
admin.initStudentCouponValue().then(() => {
couponValue = admin.getStudentCouponValue()
});
and later we can use
coupoValue
for inputs

React Native: Reach-Navigation and Pouch-DB - db.put not done before "refresh" callback is run

Relative newbie; forgive me if my etiquette and form here aren't great. I'm open to feedback.
I have used create-react-native-app to create an application using PouchDB (which I believe ultimately uses AsyncStorage) to store a list of "items" (basically).
Within a TabNavigator (main app) I have a StackNavigator ("List screen") for the relevant portion of the app. It looks to the DB and queries for the items and then I .map() over each returned record to generate custom ListView-like components dynamically. If there are no records, it alternately displays a prompt telling the user so. In either case, there is an "Add Item" TouchableOpacity that takes them to a screen where they an add a new item (for which they are taken to an "Add" screen).
When navigating back from the "Add" screen I'm using a pattern discussed quite a bit here on SO in which I've passed a "refresh" function as a navigation param. Once the user uses a button on the "Add" screen to "save" the changes, it then does a db.post() and adds them item, runs the "refresh" function on the "List screen" and then navigates back like so:
<TouchableOpacity
style={styles.myButton}
onPress={() => {
if (this.state.itemBrand == '') {
Alert.alert(
'Missing Information',
'Please be sure to select a Brand',
[
{text: 'OK', onPress: () =>
console.log('OK pressed on AddItemScreen')},
],
{ cancelable: false }
)
} else {
this.createItem();
this.props.navigation.state.params.onGoBack();
this.props.navigation.navigate('ItemsScreen');
}
}
}
>
And all of this works fine. The "refresh" function (passed as onGoBack param) works fine... for this screen. The database is called with the query, the new entry is found and the components for the item renders up like a charm.
Each of the rendered ListItem-like components on the "List screen" contains a react-native-slideout with an "Edit" option. An onPress for these will send the user to an "Item Details" screen, and the selected item's _id from PouchDB is passed as a prop to the "Item Details" screen where loadItem() runs in componentDidMount and does a db.get(id) in the database module. Additional details are shown from a list of "events" property for that _id (which are objects, in an array) which render out into another bunch of ListItem-like components.
The problem arises when either choose to "Add" an event to the list for the item... or Delete it (using another function via [another] slideout for these items. There is a similar backward navigation, called in the same form as above after either of the two functions is called from the "Add Event" screen, this being the "Add" example:
async createEvent() {
var eventData = {
eventName: this.state.eventName.trim(),
eventSponsor: this.state.eventSponsor.trim(),
eventDate: this.state.eventDate,
eventJudge: this.state.eventJudge.trim(),
eventStandings: this.state.eventStandings.trim(),
eventPointsEarned: parseInt(this.state.eventPointsEarned.trim()),
};
var key = this.key;
var rev = this.rev;
await db.createEvent(key, rev, eventData);
}
which calls my "db_ops" module function:
exports.createEvent = function (id, rev, eventData) {
console.log('You called db.createEvent()');
db.get(id)
.then(function(doc) {
var arrWork = doc.events; //assign array of events to working variable
console.log('arrWork is first assigned: ' + arrWork);
arrWork.push(eventData);
console.log('then, arrWork was pushed and became: ' + arrWork);
var arrEvents = arrWork.sort((a,b)=>{
var dateA = new Date(a.eventDate), dateB = new Date(b.eventDate);
return b.eventDate - a.eventDate;
})
doc.events = arrEvents;
return db.put(doc);
})
.then((response) => {
console.log("db.createEvent() response was:\n" +
JSON.stringify(response));
})
.catch(function(err){
console.log("Error in db.createEvent():\n" + err);
});
}
After which the "Add Event" screen's button fires the above in similar sequence to the first, just before navigating back:
this.createEvent();
this.props.navigation.state.params.onGoBack();
this.props.navigation.navigate('ItemsDetails');
The "refresh" function looks like so (also called in componentDidMount):
loadItem() {
console.log('Someone called loadItem() with this.itemID of ' + this.itemID);
var id = this.itemID;
let totalWon = 0;
db.loadItem(id)
.then((item) => {
console.log('[LOAD ITEM] got back data of:\n' + JSON.stringify(item));
this.setState({objItem: item, events: item.events});
if (this.state.events.length != 0) { this.setState({itemLoaded: true});
this.state.events.map(function(event) {
totalWon += parseInt(event.eventPointsEarned);
console.log('totalWon is ' + totalWon + ' with ' +
event.eventPointsEarned + ' having been added.');
});
};
this.setState({totalWon: totalWon});
})
.catch((err) => {
console.log('db.loadItem() error: ' + err);
this.setState({itemLoaded: false});
});
}
I'm at a loss for why the List Screen refreshes when I add an item... but not when I'm doing other async db operations with PouchDB in what I think is similar fashion to modify the object containing the "event" information and then heading back to the Item Details screen.
Am I screwing up with Promise chain someplace? Neglecting behavior of the StackNavigator when navigating deeper?
The only other difference being that I'm manipulating the array in the db function in the non-working case, whereas the others I'm merely creating/posting or deleting/removing the record, etc. before going back to update state on the prior screen.
Edit to add, as per comments, going back to "List screen" and the opening "Item Details" does pull the database data and correctly shows that the update was made.
Further checking I've done also revealed that the console.log in createEvent() to print the response to the db call isn't logging until after some of the other dynamic rendering methods are getting called on the "Item Details" screen. So it seems as though the prior screen is doing the get() that loadItem() calls before the Promise chain in createEvent() is resolving. Whether the larger issue is due to state management is still unclear -- though it would make sense in some respects -- to me as this could be happening regardless of whether I've called my onGoBack() function.
Edit/bump: I’ve tried to put async/await to use in various places in both the db_ops module on the db.get() and the component-side loadItem() which calls it. There’s something in the timing of these that just doesn’t jive and I am just totally stuck here. Aside from trying out redux (which I think is overkill in this particular case), any ideas?
There is nothing to do with PDB or navigation, it's about how you manage outer changes in your depending (already mounted in Navigator since they are in history - it's important to understand - so componentDidMount isn't enough) components. If you don't use global state redux-alike management (as I do) the only way to let know depending component that it should update is passing corresponding props and checking if they were changed.
Like so:
//root.js
refreshEvents = ()=> { //pass it to DeleteView via screenProps
this.setState({time2refreshEvents: +new Date()}) //pass time2refreshEvents to EventList via screenProps
}
//DeleteView.js
//delete button...
onPress={db.deleteThing(thingID).then(()=> this.props.screenProps.refreshEvents())}
//EventList.js
...
constructor(props) {
super(props);
this.state = {
events: [],
noEvents: false,
ready: false,
time2refreshEvents: this.props.screenProps.time2refreshEvents,
}
}
static getDerivedStateFromProps(nextProps, currentState) {
if (nextProps.screenProps.time2refreshEvents !== currentState.time2refreshEvents ) {
return {time2refreshEvents : nextProps.screenProps.time2refreshEvents }
} else {
return null
}
}
componentDidMount() {
this._getEvents()
}
componentDidUpdate(prevProps, prevState) {
if (this.state.time2refreshEvents !== prevState.time2refreshEvents) {
this._getEvents()
}
}
_getEvents = ()=> {
//do stuff querying db and updating your list with actual data
}

React-native and Redux healthy way to call actions on props change

I've been using react-native with redux for a while, and the way i learn to call actions when something change on prop is using the componentWillReceiveProps, but when I use it I need to pass between if's and some times it goes to the wrong if, then I need to add more stuff to prevent it.
Here's an example I have done. I know this is not the best way to do it, but it is what I could think of.
componentWillReceiveProps(newProps) {
if(Object.keys(newProps.selected_product).length > 0) {
if(Object.keys(this.props.current_location).length > 0 || Object.keys(newProps.current_location).length > 0) {
this._handleNextPage(2);
this.props.verifyProductById(newProps.selected_product, newProps.current_location, this.props.token);
} else {
this.props.statusScanner(false);
this._handleNextPage(1);
}
} else if(Object.keys(newProps.historic_product_confirm).length > 0) {
if(newProps.historic_product_confirm.location._id == newProps.current_location._id)
this.props.handleModalConfirmPrice(!this.props.modal_confirmPrice_status)
} else if(newProps.scanResult != "") {
this.props.statusScanner(false);
if(Object.keys(newProps.current_location).length > 0) {
this._handleNextPage(2);
} else {
this._handleNextPage(1);
}
} else {
this._handleNextPage(0);
}
}
What I need is a healthy way to call my actions when the props change.
Edit:
Here i have the full OfferScene and an action file example:
OfferScene:
https://gist.github.com/macanhajc/0ac98bbd2974d2f6fac96d9e30fd0642
UtilityActions:
https://gist.github.com/macanhajc/f10960a8254b7659457f8a09c848c8cf
As mentioned in another answer, componentWillReceiveProps is being phased out, so I would aim for trying to eliminate it where possible. You'll be future-proofing your code and keeping your component logic more declarative and easy to reason about. As someone who has been responsible for (and been frustrated by) lifecycle method abuse like this, here are some things that have helped me.
Remember that when using redux-thunk, along with passing dispatch as the first argument, you can also pass getState as the second. This allows you to access state values in your action logic instead of bringing them into your component's props and adding clutter. Something like:
export const ExampleAction = update =>
(dispatch, getState) => {
const { exampleBool } = getState().ExampleReducer
if (exampleBool) {
dispatch({
type: 'UPDATE_EXAMPLE_STATE',
update
})
}
}
Using async/await in action logic can be a lifesaver when your action depends upon fetched results from an API call:
export const ExampleAction = () =>
async (dispatch, getState) => {
const { valueToCheck } = getState().ExampleReducer
, result = await someAPICall(valueToCheck)
.catch(e => console.log(e))
if (result.length > 0) {
dispatch({
type: 'UPDATE_EXAMPLE_STATE',
update: result
})
}
}
For cases where your component's rendering behavior depends upon certain state values after your state has been updated, I highly recommend reselect. A very basic example would be something like:
component.js
import React, { Component, Fragment } from 'react'
import { connect } from 'react-redux'
import { shouldDisplayItems } from '../selectors'
import MyListviewComponent from './myListview'
class ItemList extends Component {
render() {
const { shouldDisplayItems, items } = this.props
return (
<>
{shouldDisplayItems && <MyListviewComponent items={items} />}
</>
)
}
}
const mapStateToProps = ({ ListItems }) => shouldDisplayItems(ListItems)
export default connect(mapStateToProps)(ItemList)
selectors.js:
(Assuming your ListItems reducer has the params items and visibilityFilter)
import { createSelector } from 'reselect'
export const shouldDisplayItems = createSelector(
[state => state],
({ items, visibilityFilter }) => {
return {
shouldDisplayItems: visibilityFilter && items.length > 0,
items
}
}
)
I should mention that another option would be using higher-order components, but it can be tricky to use this approach before having a good grasp on how to keep too much imperative logic out of your components (I learned this the hard way).
I agree with #AnuragChutani and #Goldy in terms of clarity of the code; break it down some more into more components or functions.
Now after some review of your componentWillReceiveProps function, it is definitely not specific enough to narrow down exactly which prop changes. If any connected redux variable changes, the componentWillReceiveProps function will be invoked each time.
So e.g. if 'token' or 'selected_product' updates, componentWillReceiveProps will be triggered, even though you did not want it to trigger for token updates.
You can use a comparison for a specific variable update in the props.
E.g Using lodash
if(!_.isEqual( nextProps.selected_product, this.props.selected_product ))
// if props are different/updated, do something
Secondly, you can call actions/callbacks in your actions to narrow down navigation.
E.g.
takePicture = (camera, options){
...
//on success
dispatch(handleModalConfirmPrice())
...
}}

Protractor: Is it possible to check if an element doesn't contain certain text?

On the page that I am testing, a user can have a single currency or multiple currencies (i.e EUR and USD)the currency/currencies will appear in the same div at the top of the page.
If a user has multiple currencies, a tab for each currency will appear further down the page, if a user has only one currency, no tabs will appear (as there is no need for the user to switch tabs).
I am able to test multi currency users by checking to see if the text contained in the header matches the text contained in the currencies tabs.
However, as no tabs appear for a single currency, I'm not sure how to test this.
For example, if I have only a 'EUR' currency, is there a way to do something like
if element(by.className("currencies"))contains 'EUR'
&& doesn't contain 'USD' && doesn't contain 'GBP'
expect element(by.className("tabs").toDisplay.toBeFalsy()
This is the code for the page object file
this.checkCurrency = function(currency) {
var checkBalance = element(by.className("balances"));
checkBalance.getText().then(function (text) {
if (text.indexOf("GBP" && "EUR")>= 0) {
expect(element.all(by.linkText("GBP")).isDisplayed()).toBeTruthy();
console.log("EUR GBP buyer");
}
else if (text.indexOf("GBP" && "USD")>= 0) {
expect(element.all(by.linkText('USD')).isDisplayed()).toBeTruthy();
console.log("USD GBP buyer");
}
else
{
console.log("false");
}
});
};
From your description I'm not quite sure where the failure is. In general you want to keep this kind of logic out of your page object. Your test should understand what state the page should be in and call different functions. I know that's not always possible, but it works out so much better if you can. Here is some general condition advise that should help.
You can catch the success state and a failed state of a promise. Most people use the pass function, but forget about the fail function.
promise.then(passFunction, failFunction)
You can use this in several different ways. If you realize that almost everything in protractor is returning a promise.
Example:
element(by.className("currencies")).getText()
.then(
function(text) {
//check on something
},function(error){
//don't check on something
if(someCondition) {
throw error;
} else {
//the test continues
}
});
You can even do it with and expect
expect(element(by.className("currencies")).getText()).not.toContain("EUR")
.then(
function(passed) {
//check on something
},function(failed){
//don't check on something
if(someCondition) {
throw failed;
} else {
//the test continues
}
});
Or a simple findElement
element(by.className("currencies"))
.then(
function(element) {
//check on something
},function(error){
//don't check on something
if(someCondition) {
throw failed;
} else {
//the test continues
}
});

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