Develop Reference

list of ref shows undefined when logging

I've made a list of refs for each of my components that is being rendered in a map, I am assigning a ref to a button within EditWebAppTypeForm and am trying to use it within MappedAccordion but it shows undefined? what can I do to make sure ref is set before passing it in the MappedAccordion component?
The information logged in addtoRefs function is correct, it shows -
(2) [button, button]
I've removed a lot of the code so its easier to read.
function Admin() {
const allRefs = useRef([] as any);
allRefs.current = [];
const addtoRefs = (e: any) => {
if (e && !allRefs?.current?.includes(e)) {
allRefs?.current?.push(e);
}
console.log(allRefs.current); <-- Logs correct info
};
return (
<div className="adminContainer">
<Grid container spacing={2}>
<Grid item md={8} xs={12} sm={12}>
<div style={{ width: 725, paddingBottom: 150 }}>
{webAppTypes &&
webAppTypes.map((a: IWebAppType, index: number) => {
return (
<>
<Accordion
key={a.id}
defaultExpanded={a.id === 0 ? true : false}
>
<AccordionDetails>
<EditWebAppTypeForm
key={a.name}
setWebAppTypes={setWebAppTypes}
IWebAppTypeModel={a}
ref={addtoRefs} // <-- returning ref to add to list
/>
<MappedAccordion
waobj={a}
key={a.id}
setWebAppTypes={setWebAppTypes}
editRef={allRefs.current[index]} <-- using ref but showing undefined in MappedAccordion component
/>
</AccordionDetails>
</Accordion>
</>
);
})}
</div>
</Grid>
</Grid>
</div>
);
}
export default Admin;
EditWebAppTypeForm Component -
const EditWebAppTypeForm = (props: any, ref: any) => {
return (
<div className="editWebAppSContainer">
<form onSubmit={handleSubmit(onSubmit)} id="edit-app-form">
<button hidden={true} ref={ref} type="submit" /> // <-- Assiging ref to button
</form>
</div>
);
};
export default forwardRef(EditWebAppTypeForm);
type MappedAccordionProps = {
waobj: IWebAppType;
setWebAppTypes: Dispatch<SetStateAction<IWebAppType[]>>;
editRef: any;
};
function MappedAccordion({
waobj,
setWebAppTypes,
editRef,
}: MappedAccordionProps) {
const onSubmit = (data: FormFields) => {
console.log(editRef); // <-- Logs undefined
};
return (
<div>
<form onSubmit={handleSubmit(onSubmit)} id="environment-form">
</form>
</div>
);
}
export default MappedAccordion;

I would create an extra component WebAppTypeAccordion like this :
function WebAppTypeAccordion({a, setWebAppTypes}) {
const [formEl, setFormEl] = useState(null);
function handleRef(el) {
if (el) {
setFormEl(el)
}
}
return (
<Accordion defaultExpanded={a.id === 0}>
<AccordionDetails>
<EditWebAppTypeForm
setWebAppTypes={setWebAppTypes}
IWebAppTypeModel={a}
ref={handleRef}
/>
<MappedAccordion
waobj={a}
setWebAppTypes={setWebAppTypes}
editRef={formEl}
/>
</AccordionDetails>
</Accordion>
);
}
Then you can update the Admin component :
webAppTypes.map((a: IWebAppType) => (
<WebAppTypeAccordion key={a.id] a={a} setWebAppTypes={setWebAppTypes} />
))

Resetting a form when using onBlur as opposed to onChange

I had a form that has a lot of lag due to a large amount of state being handled for user's with a large number of job posts etc. I am trying to subdue this lag my switching my onChange to onBlur, this works great. The only problem is that my form no longer gets set to InitialState( empty string). I also have a submit button that I am keeping invalid until all inputs are filled. due to the onblur it remains invalid until I click away from the form. Is there a way I can still reset a form when using onBlur?? and does anyone have a solution to the issue of my button remaining invalid until I click away from the form. My inputs code are as follows:
the handleSubmit function:
const handleSubmit = async e => {
e.preventDefault()
setIsLoading(true)
const fireToken = await localStorage.FBIdToken
await axios
.post(`/job`, formData, {
headers: {
Authorization: `${fireToken}`
}
})
.then(res => {
setOpen(true)
setMessage(res.data)
fetchUser()
setIsLoading(false)
setIsModalOpen(false)
setFormData(INITIAL_STATE)
})
.catch(err => {
setErrors(err.response.data)
console.log(err)
setIsLoading(false)
})
}
The form code:
import React from 'react'
// components
import SelectStatus from './SelectStatus'
// Material UI Stuff
import CircularProgress from '#material-ui/core/CircularProgress'
import Typography from '#material-ui/core/Typography'
import TextField from '#material-ui/core/TextField'
import CardContent from '#material-ui/core/CardContent'
import Button from '#material-ui/core/Button'
import Card from '#material-ui/core/Card'
import Grid from '#material-ui/core/Grid'
// JobCardStyles
import useJobCardStyles from '../styles/JobCardStyles'
const NewJobForm = React.forwardRef(
({ handleSubmit, formData, handleInputChange, isloading }, ref) => {
const { company, position, status, link } = formData
const isInvalid = !company || !position || !link || !status || isloading
const classes = useJobCardStyles()
return (
<Card className={classes.card}>
<CardContent className={classes.content}>
<form noValidate onSubmit={handleSubmit} className={classes.form}>
<Grid
container
spacing={2}
alignItems="center"
justify="space-between"
>
<Grid item sm="auto" xs={12} className={classes.grid}>
<Typography>New</Typography>
<Typography>Job</Typography>
</Grid>
<Grid item sm={3} xs={12} className={classes.grid}>
<TextField
className={classes.jobField}
margin="normal"
fullWidth
id="company"
type="company"
label="Company"
name="company"
autoComplete="company"
defaultValue={company}
onBlur={handleInputChange('company')}
/>
</Grid>
<Grid item sm={3} xs={12} className={classes.grid}>
<TextField
className={classes.jobField}
margin="normal"
fullWidth
id="position"
type="position"
label="Position"
name="position"
autoComplete="position"
defaultValue={position}
onBlur={handleInputChange('position')}
/>
</Grid>
<Grid item sm={2} xs={12} className={classes.grid}>
<SelectStatus
status={status}
handleInputChange={handleInputChange}
/>
</Grid>
<Grid item sm={2} xs={12} className={classes.grid}>
<TextField
className={classes.jobField}
margin="normal"
fullWidth
id="link"
type="text"
label="Link"
name="link"
autoComplete="link"
defaultValue={link}
onBlur={handleInputChange('link')}
/>
</Grid>
<Grid item sm={1} xs={12} className={classes.grid}>
<Button
fullWidth
type="submit"
variant="contained"
color="primary"
disabled={isInvalid}
className={classes.submit}
disableElevation
>
Submit
{isloading && (
<CircularProgress size={30} className={classes.progress} />
)}
</Button>
</Grid>
</Grid>
</form>
</CardContent>
</Card>
)
}
)
export default NewJobForm

Try making another function to wrap several functions.
const NewJobForm = React.forwardRef(
//other logic
const reset = () => {//your reset function logic}
//ver 1
const handleOnBlur = (fn, relatedParam) => {
reset();
fn(relatedParam);
}
//ver 2
const handleOnBlur = (relatedParam) => {
reset();
handleInputChange(relatedParam);
}
return (
<TextField
//other props
onBlur={() => handleOnBlur('company')}
/>
)

Unable to get the input from a textfield in React

I'm trying to get the input from a text-field in react but it just doesn't work and I have no clue why. I have looked at a lot of different solutions but none of them seem to work.
I even tried to follow this https://reactjs.org/docs/refs-and-the-dom.html but I'm not understanding this correctly?
class Activity extends Component {
constructor(props) {
super(props);
this.newActivity = React.createRef();
}
callAPI() {
fetch("http://localhost:5000/activities", {
method: 'POST',
body: JSON.stringify({
newName: this.newActivity.current,
oldName: this.state.activity
}),
})
.then(function (response) {
return response.json()
});
}
state = {
activity: this.props.data.name
}
render() {
return (
<React.Fragment>
<Grid justify="center" container spacing={(2, 10)} aligncontent="center">
<Grid item xs={8} >
<Paper>
{/*Trying to get the input here so that I can put it into my POST request*/}
<TextField inputRef={el => this.newActivity = el} type="activity" id="standard-basic" label="Standard" defaultValue={this.state.activity} />
</Paper>
</Grid>
<Grid item xs={2}>
<Button onClick={this.callAPI} variant="contained" startIcon={<UpdateIcon />} style={buttonStyle} >Uppdatera</Button>
</Grid>
<Grid item xs={2}>
<Button variant="contained" startIcon={<DeleteIcon />} style={buttonStyle} >Ta Bort</Button>
</Grid>
</Grid>
</React.Fragment>
);
}
}
The error I get is
TypeError: Cannot read property 'newActivity' of undefined

You must initiate state values inside the constructor.
Also change this line as inputRef={this.newActivity} instead of inputRef={(el)=>this.newActivity =el}. Because you already create ref using createRef no need to create again.
class Activity extends Component {
constructor(props) {
super(props);
this.state = {
activity: this.props.data.name
}
this.callAPI = this.callAPI.bind(this);
this.newActivity = React.createRef();
}
callAPI() {
fetch("http://localhost:5000/activities", {
method: 'POST',
body: JSON.stringify({
newName: this.newActivity.current,
oldName: this.state.activity
}),
})
.then(function (response) {
return response.json()
});
}
render() {
return (
<React.Fragment>
<Grid justify="center" container spacing={(2, 10)} aligncontent="center">
<Grid item xs={8} >
<Paper>
{/*Trying to get the input here so that I can put it into my POST request*/}
<TextField inputRef={this.newActivity} type="activity" id="standard-basic" label="Standard" defaultValue={this.state.activity} />
</Paper>
</Grid>
<Grid item xs={2}>
<Button onClick={this.callAPI} variant="contained" startIcon={<UpdateIcon />} style={buttonStyle} >Uppdatera</Button>
</Grid>
<Grid item xs={2}>
<Button variant="contained" startIcon={<DeleteIcon />} style={buttonStyle} >Ta Bort</Button>
</Grid>
</Grid>
</React.Fragment>
);
}

TextField is a wrapper component.
You can pass the ref to the native input like this:
import React, { Component, createRef } from 'react';
import TextField from '#material-ui/core/TextField';
export default class App extends Component {
ref = createRef();
render() {
return (
<div className="App">
<TextField inputProps={{ ref: this.ref }} />
</div>
);
}
}

Auto scroll react redux implementation

I am implementing auto-scroll option for my application. In below case channels are list of data which fetch from database. I used redux to call api. how can i connect InfiniteScroll and channels list to get auto-scroll feature?
import React, { Fragment } from "react";
import { Grid } from "#material-ui/core";
import ChannelCard from "./Card";
import CreateChannel from "./Create";
import SimpleSelect from "./Filter";
import InfiniteScroll from "react-infinite-scroll-component";
const ChannelList = ( {channels: { channels}}) => {
const [data, setData] = React.useState({
items: Array.from({ length: 20 })
});
const { items } = data;
const fetchMoreData = () => {
// a fake async api call like which sends
// 20 more records in 1.5 secs
setTimeout(() => {
setData({
items: items.concat(Array.from({ length: 20 }))
});
}, 1500);
};
//view
const view = (
<Fragment>
<Grid container>
<Grid item xs={6} sm={6} md={10} lg={10} xl={10}></Grid>
<Grid>
<SimpleSelect />
</Grid>
</Grid>
<Fragment>
<InfiniteScroll
dataLength={items.length}
next={fetchMoreData}
hasMore={true}
loader={<h4>Loading...</h4>}
>
<Grid container>
{channels.map(channel => (
<Grid key={channel._id} item xs={6} sm={6} md={3} lg={2} xl={2}>
<ChannelCard
channel={channel}
isAuthenticated={isAuthenticated}
/>
</Grid>
))}
</Grid>
</InfiniteScroll>
</Fragment>
</Fragment>
);
return <Fragment>{view}</Fragment>;
};
export default ChannelList;
(I used redux to call api. how can i connect InfiniteScroll and channels list to get auto-scroll feature?)

InfiniteScroll component requires the children to be the array of components that you want to have infinite scrolling on, since you have only one child which is the Grid component it is doing its job for only one item hence its not working: https://www.npmjs.com/package/react-infinite-scroll-component
just remove the wrapping Grid component
<InfiniteScroll
dataLength={items.length}
next={fetchMoreData}
hasMore={true}
loader={<h4>Loading...</h4>}
>
{channels.map(channel => (
<Grid key={channel._id} item xs={6} sm={6} md={3} lg={2} xl={2}>
<ChannelCard
channel={channel}
isAuthenticated={isAuthenticated}
/>
</Grid>
))}
</InfiniteScroll>

Call child hook function from parent using refs

I'm switching over to building components using Hooks and i'm struggling to setup refs with useRef()
Parent (The ref is only added to one component currently, as I'd like to ensure this is working before extending functionality to others):
export default function UserPanels({ selected_client } ) {
const classes = useStyles();
const [value, setValue] = useState(0);
const container = useRef( null );
function handleChange(event, newValue) {
setValue(newValue);
container.current.displayData();
}
return (
<div className={classes.root}>
<UserTabs
value={value}
onChange={handleChange}
indicatorColor="primary"
textColor="primary"
variant="fullWidth"
aria-label="full width tabs example"
>
<Tab label='Service User' {...a11yProps(0)} />
<Tab label='Care Plan' {...a11yProps(1)} />
<Tab label='Contacts' {...a11yProps(2)} />
<Tab label='Property' {...a11yProps(3)} />
<Tab label='Schedule' {...a11yProps(4)} />
<Tab label='Account' {...a11yProps(5)} />
<Tab label='Invoices' {...a11yProps(6)} />
<Tab label='Notes' {...a11yProps(7)} />
<Tab label='eMAR' {...a11yProps(8)} />
</UserTabs>
<TabPanel value={value} index={0}>
<UserDetailsContainer
selected_client={ selected_client }
/>
</TabPanel>
<TabPanel value={value} index={1}>
Care Plan
</TabPanel>
<TabPanel value={value} index={2}>
<ContactsContainer
ref={ container }
selected_client={ selected_client }
/>
</TabPanel>
<TabPanel value={value} index={3}>
Property
</TabPanel>
<TabPanel value={value} index={4}>
Schedule
</TabPanel>
<TabPanel value={value} index={5}>
Account
</TabPanel>
<TabPanel value={value} index={6}>
Invoices
</TabPanel>
<TabPanel value={value} index={7}>
Notes
</TabPanel>
<TabPanel value={value} index={8}>
eMAR
</TabPanel>
</div>
);
}
Child:
export default function ContactsContainer( props ) {
const [ state, setState ] = useState({
contact_records: contacts,
data_ready: true
});
function displayData() {
console.log( 'display time' );
}
if ( !state.data_ready ) return null
return (
<>
{
state.contact_records.map( ( contact ) => {
return <ContactRecord contact={ contact } />
} )
}
</>
)
}
Essentially, I'm trying to call a child function from the parent but ref.current evaluates to null and when handleChange() is invoked I receive the error container.current is null and I regularly see the error Function components cannot be given refs. Attempts to access this ref will fail. Did you mean to use React.forwardRef()?
As a note, I've already tested forwardRef:
<ContactsContainer
ref={ container }
selected_client={ selected_client }
/>
And, while this removes the error, it does not solve the issue. I've never had an issue using refs with class components but I seem to be missing something here.

First of all, don't overuse refs ( react doc). You must not control your child component by call directly its functions (and honestly you can't do this with function components).
If you need to display something in your children, you have to prepare data in your parent component and pass that data by props. Children should be as simple as possible. They should get props and displaying some data.
In parent:
const [value, setValue] = useState(0);
const [time, setTime] = useState(null);
function handleChange(event, newValue) {
setValue(newValue);
setTime('display time');
}
return (
....
<ContactsContainer
time={time}
selected_client={ selected_client }
/>
....
)
If you need to make some side effects (e.g. make HTTP calls, dispatch Redux actions) in your child when props changes, you have to use useEffect hook.
In parent:
<ContactsContainer
value={value}
selected_client={ selected_client }
/>
In child:
useEffect(() => {
console.log('display time action');
}, [props.value]);

you can pass a ref as a prop:
// ...
const infoRef=useRef(null)
useEffect(()=>{
if(infoRef.current) infoRef.current()
},[])
return <ChildComponent infoRef={infoRef} />
and then in child:
useEffect(()=>{
infoRef.current=childFunctionToExecuteInParent
},[])