I have a button in my component that will execute DeleteNote property which i want to remove an array element on onClick event.
DeleteNote = (id) =>
{
const allNotes = [...this.state.notes];
const selectedNoteIndex = allNotes.findIndex(e => e.id == id)
allNotes.splice(selectedNoteIndex, 1)
this.setState({ notes: allNotes })
}
But this method seems to not re-render the component.
Anyway when i try with this method, it re-render perfectly.
MoveToArchive = (id) =>
{
const allNotes = [...this.state.notes];
const selectedNoteIndex = allNotes.findIndex(e => e.id == id)
allNotes[selectedNoteIndex].archived = true;
this.setState({ notes: allNotes })
}
What is lacking in my DeleteNote property in order to delete an element?
Been reading all resources but nothing seems to work.
Render :
Display = () =>
{
return (
<>
<HeaderContainer notesData={this.state.notes} searchMethod={this.SearchNotes} />
<MainContainer notesData={this.state.notes} deleteMethod={this.DeleteNote} archiveMethod={this.MoveToArchive} activeMethod={this.MoveToActive} />
<NewModal />
<DeleteModal deleteAllMethod={this.DeleteAllNotes} />
</>
)
}
render()
{
return (this.Display())
}
try this:
DeleteNote = (id) =>
{
const allNotes = [...this.state.notes];
const selectedNoteIndex = allNotes.findIndex(e => e.id == id)
allNotes.splice(selectedNoteIndex, 1)
this.setState({ notes: [...allNotes] })
}
Can you try this code for deleting
DeleteNote = (id) => {
const newNotes = this.state.notes.filter(e => e.id !== id)
this.setState({ notes: newNotes })
}
Related
***//How can I change the select value to true of the checked object?***
const App = () => {
const data = [{id:1, msg:"t", select:false}, {id:2, msg:"t2, select:false}]
const handleChange = (e) => {
if(checked){
data.select === true
}
}
//``To check the particular object I want to set the value true for that object and rendered the false as an unchecked value
return(
{data.map(d => {
<Checkbox
value={d}
checked={d.select}
onChange-{handleChange}
/>
}
)
}
You just have to pass the id to handleChange like this:
return(
{data.map(d => {
<Checkbox
value={d}
checked={d.select}
onChange-{(e)=>handleChange(e,d.id)}
/>
}
and change handleChange to be something like this
const handleChange = (e,id) => {
const index = data.findIndex(element => element.id === id) // here we get the index of the element
if(checked){
data[index].select = true
}
}
I am trying to delete multiple items on click of checkbox using firestore. But, onSnapshot method of firestore is causing issue with the state.
After running the code I can click on checkbox and delete the items, the items get deleted too but I get an error page, "TyperError: this.setState is not a function" in onCollectionUpdate method.
After refreshing the page I can see the items deleted.
Here's my code:
class App extends React.Component {
constructor(props) {
super(props);
this.ref = firebase.firestore().collection('laptops');
this.unsubscribe = null;
this.state = { laptops: [], checkedBoxes: [] };
this.toggleCheckbox = this.toggleCheckbox.bind(this);
this.deleteProducts = this.deleteProducts.bind(this);
}
toggleCheckbox = (e, laptop) => {
if (e.target.checked) {
let arr = this.state.checkedBoxes;
arr.push(laptop.key);
this.setState = { checkedBoxes: arr };
} else {
let items = this.state.checkedBoxes.splice(this.state.checkedBoxes.indexOf(laptop.key), 1);
this.setState = {
checkedBoxes: items
}
}
}
deleteProducts = () => {
const ids = this.state.checkedBoxes;
ids.forEach((id) => {
const delRef = firebase.firestore().collection('laptops').doc(id);
delRef.delete()
.then(() => { console.log("deleted a laptop") })
.catch(err => console.log("There is some error in updating!"));
})
}
onCollectionUpdate = (querySnapshot) => {
const laptops = [];
querySnapshot.forEach((doc) => {
const { name, price, specifications, image } = doc.data();
laptops.push({
key: doc.id,
name,
price,
specifications,
image
});
});
this.setState({ laptops });
console.log(laptops)
}
componentDidMount = () => {
this.unsubscribe = this.ref.onSnapshot(this.onCollectionUpdate);
}
getLaptops = () => {
const foundLaptops = this.state.laptops.map((laptop) => {
return (
<div key={laptop.key}>
<Container>
<Card>
<input type="checkbox" className="selectsingle" value="{laptop.key}" checked={this.state.checkedBoxes.find((p) => p.key === laptop.key)} onChange={(e) => this.toggleCheckbox(e, laptop)} />
...carddata
</Card>
</Container>
</div>
);
});
return foundLaptops;
}
render = () => {
return (
<div>
<button type="button" onClick={this.deleteProducts}>Delete Selected Product(s)</button>
<div className="row">
{this.getLaptops()}
</div>
</div>
);
}
}
export default App;
In the toggleCheckbox function you set the this.setState to a object.
You will need to replace that with this.setState({ checkedBoxes: items})
So you use the function instead of setting it to a object
You probably just forgot to bind the onCollectionUpdate so this referes not where you expectit to refer to.
Can you pls also change the this.setState bug you have there as #David mentioned also:
toggleCheckbox = (e, laptop) => {
if (e.target.checked) {
let arr = this.state.checkedBoxes;
arr.push(laptop.key);
this.setState({ checkedBoxes: arr });
} else {
let items = this.state.checkedBoxes.splice(this.state.checkedBoxes.indexOf(laptop.key), 1);
this.setState({
checkedBoxes: items
})
}
}
If you already did that pls update your question with the latest code.
I've been having trouble using React's useContext hook. I'm trying to update a state I got from my context, but I can't figure out how. I manage to change the object's property value I wanted to but I end up adding another object everytime I run this function. This is some of my code:
A method inside my "CartItem" component.
const addToQuantity = () => {
cartValue.forEach((item) => {
let boolean = Object.values(item).includes(props.name);
console.log(boolean);
if (boolean) {
setCartValue((currentState) => [...currentState, item.quantity++])
} else {
return null;
}
});
};
The "Cart Component" which renders the "CartItem"
const { cart, catalogue } = useContext(ShoppingContext);
const [catalogueValue] = catalogue;
const [cartValue, setCartValue] = cart;
const quantiFyCartItems = () => {
let arr = catalogueValue.map((item) => item.name);
let resultArr = [];
arr.forEach((item) => {
resultArr.push(
cartValue.filter((element) => item === element.name).length
);
});
return resultArr;
};
return (
<div>
{cartValue.map((item, idx) => (
<div key={idx}>
<CartItem
name={item.name}
price={item.price}
quantity={item.quantity}
id={item.id}
/>
<button onClick={quantiFyCartItems}>test</button>
</div>
))}
</div>
);
};
So how do I preserve the previous objects from my cartValue array and still modify a single property value inside an object in such an array?
edit: Here's the ShoppingContext component!
import React, { useState, createContext, useEffect } from "react";
import axios from "axios";
export const ShoppingContext = createContext();
const PRODUCTS_ENDPOINT =
"https://shielded-wildwood-82973.herokuapp.com/products.json";
const VOUCHER_ENDPOINT =
"https://shielded-wildwood-82973.herokuapp.com/vouchers.json";
export const ShoppingProvider = (props) => {
const [catalogue, setCatalogue] = useState([]);
const [cart, setCart] = useState([]);
const [vouchers, setVouchers] = useState([]);
useEffect(() => {
getCatalogueFromApi();
getVoucherFromApi();
}, []);
const getCatalogueFromApi = () => {
axios
.get(PRODUCTS_ENDPOINT)
.then((response) => setCatalogue(response.data.products))
.catch((error) => console.log(error));
};
const getVoucherFromApi = () => {
axios
.get(VOUCHER_ENDPOINT)
.then((response) => setVouchers(response.data.vouchers))
.catch((error) => console.log(error));
};
return (
<ShoppingContext.Provider
value={{
catalogue: [catalogue, setCatalogue],
cart: [cart, setCart],
vouchers: [vouchers, setVouchers],
}}
>
{props.children}
</ShoppingContext.Provider>
);
};
edit2: Thanks to Diesel's suggestion on using map, I came up with this code which is doing the trick!
const newCartValue = cartValue.map((item) => {
const boolean = Object.values(item).includes(props.name);
if (boolean && item.quantity < item.available) {
item.quantity++;
}
return item;
});
removeFromStock();
setCartValue(() => [...newCartValue]);
};```
I'm assuming that you have access to both the value and the ability to set state here:
const addToQuantity = () => {
cartValue.forEach((item) => {
let boolean = Object.values(item).includes(props.name);
console.log(boolean);
if (boolean) {
setCartValue((currentState) => [...currentState, item.quantity++])
} else {
return null;
}
});
};
Now... if you do [...currentState, item.quantity++] you will always add a new item. You're not changing anything. You're also running setCartValue on each item, which isn't necessary. I'm not sure how many can change, but it looks like you want to change values. This is what map is great for.
const addToQuantity = () => {
setCartValue((previousCartValue) => {
const newCartValue = previousCartValue.map((item) => {
const boolean = Object.values(item).includes(props.name);
console.log(boolean);
if (boolean) {
return item.quantity++;
} else {
return null;
}
});
return newCartValue;
});
};
You take all your values, do the modification you want, then you can set that as the new state. Plus it makes a new array, which is nice, as it doesn't mutate your data.
Also, if you know only one item will ever match your criteria, consider the .findIndex method as it short circuits when it finds something (it will stop there), then modify that index.
I have an array of data object to be rendered. and this array of data is populated by Firestore onSnapshot function which i have declared in the React hook: useEffect. The idea is that the dom should get updated when new data is added to firestore, and should be modified when data is modified from the firestore db.
adding new data works fine, but the problem occurs when the data is modified.
here is my code below:
import React, {useState, useEffect} from 'react'
...
const DocList = ({firebase}) => {
const [docList, setDocList] = useState([]);
useEffect(() => {
const unSubListener = firebase.wxDocs()
.orderBy("TimeStamp", "asc")
.onSnapshot({
includeMetadataChanges: true
}, docsSnap => {
docsSnap.docChanges()
.forEach(docSnap => {
let source = docSnap.doc.metadata.fromCache ? 'local cache' : 'server';
if (docSnap.type === 'added') {
setDocList(docList => [{
source: source,
id: docSnap.doc.id,
...docSnap.doc.data()
}, ...docList]);
console.log('document added: ', docSnap.doc.data());
} // this works fine
if (docSnap.type === 'modified') {
console.log('try docList from Lists: ', docList); //this is where the problem is, this returns empty array, i don't know why
console.log('document modified: ', docSnap.doc.data()); //modified data returned
}
})
})
return () => {
unSubListener();
}
}, []);
apparently, i know the way i declared the useEffect with empty deps array is to make it run once, if i should include docList in the deps array the whole effect starts to run infinitely.
please, any way around it?
As commented, you could have used setDocList(current=>current.map(item=>..., here is working example with fake firebase:
const firebase = (() => {
const createId = ((id) => () => ++id)(0);
let data = [];
let listeners = [];
const dispatch = (event) =>
listeners.forEach((listener) => listener(event));
return {
listen: (fn) => {
listeners.push(fn);
return () => {
listeners = listeners.filter((l) => l !== fn);
};
},
add: (item) => {
const newItem = { ...item, id: createId() };
data = [...data, newItem];
dispatch({ type: 'add', doc: newItem });
},
edit: (id) => {
data = data.map((d) =>
d.id === id ? { ...d, count: d.count + 1 } : d
);
dispatch({
type: 'edit',
doc: data.find((d) => d.id === id),
});
},
};
})();
const Counter = React.memo(function Counter({ up, item }) {
return (
<button onClick={() => up(item.id)}>
{item.count}
</button>
);
});
function App() {
const [docList, setDocList] = React.useState([]);
React.useEffect(
() =>
firebase.listen(({ type, doc }) => {
if (type === 'add') {
setDocList((current) => [...current, doc]);
}
if (type === 'edit') {
setDocList((current) =>
current.map((item) =>
item.id === doc.id ? doc : item
)
);
}
}),
[]
);
const up = React.useCallback(
(id) => firebase.edit(id),
[]
);
return (
<div>
<button onClick={() => firebase.add({ count: 0 })}>
add
</button>
<div>
{docList.map((doc) => (
<Counter key={doc.id} up={up} item={doc} />
))}
</div>
</div>
);
}
ReactDOM.render(<App />, document.getElementById('root'));
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.8.4/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.8.4/umd/react-dom.production.min.js"></script>
<div id="root"></div>
You can do setDocList(docList.map... but that makes docList a dependency of the effect: useEffect(function,[docList]) and the effect will run every time docList changes so you need to remove the listener and idd it every time.
In your code you did not add the dependency so docList was a stale closure. But the easiest way would be to do what I suggested and use callback for setDocList: setDocList(current=>current.map... so docList is not a dependency of the effect.
The comment:
I don't think setDocList, even with the the prevState function, is guaranteed to be up to date by the time you get into that if statement
Is simply not true, when you pass a callback to state setter the current state is passed to that callback.
Based on #BrettEast suggestion;
I know this isn't what you want to hear, but I would probably suggest using useReducer reactjs.org/docs/hooks-reference.html#usereducer, rather than useState for tracking an array of objects. It can make updating easier to track. As for your bug, I don't think setDocList, even with the the prevState function, is guaranteed to be up to date by the time you get into that if statement.
I use useReducer instead of useState and here is the working code:
import React, {useReducer, useEffect} from 'react'
import { withAuthorization } from '../../Session'
import DocDetailsCard from './Doc';
const initialState = [];
/**
* reducer declaration for useReducer
* #param {[*]} state the current use reducer state
* #param {{payload:*,type:'add'|'modify'|'remove'}} action defines the function to be performed and the data needed to execute such function in order to modify the state variable
*/
const reducer = (state, action) => {
switch (action.type) {
case 'add':
return [action.payload, ...state]
case 'modify':
const modIdx = state.findIndex((doc, idx) => {
if (doc.id === action.payload.id) {
console.log(`modified data found in idx: ${idx}, id: ${doc.id}`);
return true;
}
return false;
})
let newModState = state;
newModState.splice(modIdx,1,action.payload);
return [...newModState]
case 'remove':
const rmIdx = state.findIndex((doc, idx) => {
if (doc.id === action.payload.id) {
console.log(`data removed from idx: ${idx}, id: ${doc.id}, fullData: `,doc);
return true;
}
return false;
})
let newRmState = state;
newRmState.splice(rmIdx,1);
return [...newRmState]
default:
return [...state]
}
}
const DocList = ({firebase}) => {
const [state, dispatch] = useReducer(reducer, initialState)
useEffect(() => {
const unSubListener = firebase.wxDocs()
.orderBy("TimeStamp", "asc")
.onSnapshot({
includeMetadataChanges: true
}, docsSnap => {
docsSnap.docChanges()
.forEach(docSnap => {
let source = docSnap.doc.metadata.fromCache ? 'local cache' : 'server';
if (docSnap.type === 'added') {
dispatch({type:'add', payload:{
source: source,
id: docSnap.doc.id,
...docSnap.doc.data()
}})
}
if (docSnap.type === 'modified') {
dispatch({type:'modify',payload:{
source: source,
id: docSnap.doc.id,
...docSnap.doc.data()
}})
}
if (docSnap.type === 'removed'){
dispatch({type:'remove',payload:{
source: source,
id: docSnap.doc.id,
...docSnap.doc.data()
}})
}
})
})
return () => {
unSubListener();
}
}, [firebase]);
return (
<div >
{
state.map(eachDoc => (
<DocDetailsCard key={eachDoc.id} details={eachDoc} />
))
}
</div>
)
}
const condition = authUser => !!authUser ;
export default React.memo(withAuthorization(condition)(DocList));
also according to #HMR, using the setState callback function:
here is the updated code which also worked if you're to use useState().
import React, { useState, useEffect} from 'react'
import { withAuthorization } from '../../Session'
import DocDetailsCard from './Doc';
const DocList = ({firebase}) => {
const [docList, setDocList ] = useState([]);
const classes = useStyles();
useEffect(() => {
const unSubListener = firebase.wxDocs()
.orderBy("TimeStamp", "asc")
.onSnapshot({
includeMetadataChanges: true
}, docsSnap => {
docsSnap.docChanges()
.forEach(docSnap => {
let source = docSnap.doc.metadata.fromCache ? 'local cache' : 'server';
if (docSnap.type === 'added') {
setDocList(current => [{
source: source,
id: docSnap.doc.id,
...docSnap.doc.data()
}, ...current]);
console.log('document added: ', docSnap.doc.data());
}
if (docSnap.type === 'modified') {
setDocList(current => current.map(item => item.id === docSnap.doc.id ? {
source: source,
id: docSnap.doc.id,
...docSnap.doc.data()} : item )
)
}
if (docSnap.type === 'removed'){
setDocList(current => {
const rmIdx = current.findIndex((doc, idx) => {
if (doc.id === docSnap.doc.id) {
return true;
}
return false;
})
let newRmState = current;
newRmState.splice(rmIdx, 1);
return [...newRmState]
})
}
})
})
return () => {
unSubListener();
}
}, [firebase]);
return (
<div >
{
docList.map(eachDoc => (
<DocDetailsCard key={eachDoc.id} details={eachDoc} />
))
}
</div>
)
}
const condition = authUser => !!authUser ;
export default React.memo(withAuthorization(condition)(DocList));
Thanks hope this help whoever is experiencing similar problem.
I'm trying to translate a Class Component into a Functional one with React Native.
My Search component lets the user search for a film name and I'm making an API call to show him all corresponding films.
Here is my class component :
class Search extends React.Component {
constructor(props) {
super(props);
this.searchedText = "";
this.page = 0
this.totalPages = 0
this.state = {
films: [],
isLoading: false
}
}
_loadFilms() {
if (this.searchedText.length > 0) {
this.setState({ isLoading: true })
getFilmsFromApiWithSearchedText(this.searchedText, this.page+1).then(data => {
this.page = data.page
this.totalPages = data.total_pages
this.setState({
films: [ ...this.state.films, ...data.results ],
isLoading: false
})
})
}
}
_searchTextInputChanged(text) {
this.searchedText = text
}
_searchFilms() {
this.page = 0
this.totalPages = 0
this.setState({
films: [],
}, () => {
this._loadFilms()
})
}
render() {
return (
<View style={styles.main_container}>
<TextInput
style={styles.textinput}
placeholder='Titre du film'
onChangeText={(text) => this._searchTextInputChanged(text)}
onSubmitEditing={() => this._searchFilms()}
/>
<Button title='Rechercher' onPress={() => this._searchFilms()}/>
<FlatList
data={this.state.films}
keyExtractor={(item) => item.id.toString()}
renderItem={({item}) => <FilmItem film={item}/>}
onEndReachedThreshold={0.5}
onEndReached={() => {
if (this.page < this.totalPages) {
this._loadFilms()
}
}}
/>
</View>
)
}
}
render() {
return (
<View>
<TextInput
onChangeText={(text) => this._searchTextInputChanged(text)}
onSubmitEditing={() => this._searchFilms()}
/>
<Button title='Search' onPress={() => this._searchFilms()}/>
<FlatList
data={this.state.films}
keyExtractor={(item) => item.id.toString()}
renderItem={({item}) => <FilmItem film={item}/>}
onEndReachedThreshold={0.5}
onEndReached={() => {
if (this.page < this.totalPages) {
this._loadFilms()
}
}}
/>
{this._displayLoading()}
</View>
)
}
}
How can I translate the following with hooks :
this.page and this.totalPages ? is useRef the solution ?
in _searchFilms() I'm using setState callback to make a new API call when my film list is empty (because it's a new search). But doing it right after doesn't work because setState is asynchronous.
But I can't find a way to do it with hooks.
I think useEffect could do this but :
I only want to make this API call when my film list is empty, because I call _searchFilms() for a new search.
_loadFilms() is called on user scroll to add more films to the FlatList (for the same search) so I can't clear this.films in this case.
Here is how I translated it so far :
const Search = () => {
const [searchText, setSearchText] = useState('');
const [films, setFilms] = useState([]);
// handle pagination
const page = useRef(0);
const totalPages = useRef(0);
// handle api fetch
const [isLoading, setIsLoading] = useState(false);
const loadFilmsFromApi = () => {
getFilmsFromApiWithSearchedText(searchText, page + 1).then((data) => {
page.current = data.page;
totalPages.current = data.total_pages;
setFilms(films => [...films, ...data.results]);
setIsLoading(false);
})
};
const searchFilm = () => {
if (searchText.length > 0) {
page.current = 0;
totalPages.current = 0;
setFilms([]);
// HERE MY Films list won't be cleared (setState asynchronous)
loadFilmsFromApi();
// after the api call, clear input
setSearchText('');
}
};
useEffect(() => {
console.log(page, totalPages, "Film number" + films.length);
}, [films]);
I think you are on the right path. As for totalPages and page, having it as a ref makes sense if you want to maintain that values between different renders ( when setting state )
const Search = () => {
const [searchText, setSearchText] = useState('');
const [films, setFilms] = useState([]);
// handle pagination
const page = useRef(0);
const totalPages = useRef(0);
// handle api fetch
const [isLoading, setIsLoading] = useState(false);
// This can be invoked by either search or user scroll
// When pageNum is undefined, it means it is triggered by search
const loadFilmsFromApi = (pageNum) => {
console.log("APPEL", 'loadFills');
getFilmsFromApiWithSearchedText(searchText, pageNum ? pageNum + 1 : 1).then((data) => {
page.current = data.page;
totalPages.current = data.total_pages;
setFilms(films => {
if(pageNum) {
return [...films, ...data.results];
} else {
return [data.results];
}
});
setIsLoading(false);
})
};
useEffect(() => {
if (searchText.length > 0) {
page.current = 0;
totalPages.current = 0;
setFilms([]);
loadFilmsFromApi();
// after the api call, clear input
setSearchText('');
}
}, [searchText, loadFilmsFromApi]);
useEffect(() => {
console.log(page, totalPages, "Nombre de film " + films.length);
}, [films]);
return ( <
div > Search < /div>
);
};
<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>
Not totally clear what your question is, but it sounds like you want to clear films state before you fire off the query to the api? I am also not clear on the use of useRef here - useRef is simply a way to get a reference to an element so it's easy to access it later - like get a reference to a div and be able to access it easily via myDivRef.current
const = myDivRef = useRef;
...
<div ref={myDivRef}/>
If that is the case, then I would simply set the state of films once in the return of the API call. WRT to the refs, it seems like you this should just be normal variables, or possible state items in your function.
UPDATE:
After clearing up the goal here, you could simply add a parameter to loadFilmsFromApi to determine if you should append or overwrite:
const loadFilmsFromApi = (append) => {
getFilmsFromApiWithSearchedText(searchText, page + 1).then((data) => {
page.current = data.page;
totalPages.current = data.total_pages;
if (append) {
setFilms({
films: this.state.films.concat(data.results)
});
} else {
setFilms({
films: data.results
});
}
setIsLoading(false);
})
};