I have problem with delete item from json server. Rigth now I have a component where I stateless func component I generate li's with item from api. In another compinent I have a form, where I can add data. All works fine, till I try to delete items... The idea id to remove item after clicking (the method is on li). The weird part is, that after clicking, nothing is happening, but after refreshing the page clicked item is gone... I've als tried to use filter method, but it didn't help. In this 'app' I'm using context api to manage state.
Code:
import React, { useContext, useEffect } from 'react';
import { MovieContext } from '../contexts/MovieContext';
const MovieList = () => {
const { movies, setMovie } = useContext(MovieContext);
const handleDelete = e => {
const saved = e;
fetch(
`http://localhost:3004/movies/${e.target.id}`,
{
method: 'DELETE'
},
e.persist()
)
.then(m => m.json())
.then(() => movies.filter(movie => movie.id === saved.target.id))
.then(() => console.log(movies));
};
useEffect(() => {
console.log(movies);
});
return (
<div>
<ul>
{movies.map(movie => (
<li id={movie.id} key={movie.id} onClick={handleDelete}>
{movie.title}
</li>
))}
</ul>
</div>
);
};
export default MovieList;
thanks for any help!
Array.filter does not modify the original array; it returns a new one with the filtered elements removed. Even if it did, with React, modifying the original array doesn't change the state, you need to call the setter and pass it a new object. So you want to do setMovie(movies.filter(movie => movie.id === saved.target.id))
Related
I have an array of Notes that I get from my database, the notes objects each have a category assigned to it. There are also buttons that allow the user to filter the notes by category and only render the ones with the corresponding one.
Now, it's all working pretty well but there's one annoying thing that I can't get rid of: whenever I click on any of the buttons: <button onClick={() => {handleClick(categoryItem.category)}}>{categoryItem.category}</button>, the filterNotes() function is only called on the second click. I suspect it has to do something with me calling setState() twice, or maybe with the boolean that I set in the functions, but I tried various combinations to call the function on the first click, but to no avail so far.
Here's my MainArea code:
import React, { useState, useEffect } from "react";
import Header from "./Header";
import Footer from "./Footer";
import ListCategories from "./ListCategories";
import Note from "./Note";
import axios from "axios"
function CreateArea(props) {
const [isExpanded, setExpanded] = useState(false);
const [categories, setCategories] = useState([])
const [notes, setNotes] = useState([])
const [fetchB, setFetch] = useState(true)
const [filterOn, setFilter] = useState(false)
const [note, setNote] = useState({
title: "",
content: "",
category: ''
});
useEffect(() => {
fetch('http://localhost:5000/categories')
.then(res => res.json())
.then(json => setCategories(json))
}, [])
useEffect(() => {
if(fetchB) {
fetch('http://localhost:5000/notes')
.then(res => res.json())
.then(json => {
console.log(json)
setNotes(json)
setFetch(false)
})
}
}, [fetchB])
function handleChange(event) {
const { name, value } = event.target;
console.log("handleChange called")
setNote(prevNote => {
return {
...prevNote,
[name]: value
};
});
}
function submitNote(e){
e.preventDefault();
axios.post("http://localhost:5000/notes/add-note", note)
.then((res) => {
setNote({
category: '',
title: "",
content: ""
})
setFetch(true)
console.log("Note added successfully");
console.log(note)
})
.catch((err) => {
console.log("Error couldn't create Note");
console.log(err.message);
});
}
function expand() {
setExpanded(true);
}
function filterNotes(category){
if(filterOn){
fetch('http://localhost:5000/notes')
.then(res => res.json())
.then(json => {
console.log("filter notes")
setNotes(json)
setNotes(prevNotes => {
console.log("setNotes called with category " + category)
return prevNotes.filter((noteItem) => {
return noteItem.category === category;
});
});
setFilter(false)
})
}
}
return (
<div>
<Header/>
<ListCategories categories={categories} notes={notes} filterNotes={filterNotes} setFilter={setFilter} filterOn={filterOn} setFetch={setFetch}/>
<form className="create-note">
{isExpanded && (
<input
name="title"
onChange={handleChange}
value={note.title}
placeholder="Title"
/>
)}
<textarea
name="content"
onClick={expand}
onChange={handleChange}
value={note.content}
placeholder="Take a note..."
rows={isExpanded ? 3 : 1}
/>
<select
name="category"
onChange={handleChange}
value={note.category}>
{
categories.map(function(cat) {
return <option
key={cat.category} value={cat.value} > {cat.category} </option>;
})
}
</select>
<button onClick={submitNote}>Add</button>
</form>
<Note notes={notes} setFetch={setFetch}/>
<Footer/>
<button onClick={()=>{setFetch(true)}}>All</button>
</div>
);
}
export default CreateArea;
And ListCategories where I get call the function and get the chosen category from the buttons:
import React, { useState } from "react";
import CreateCategory from "./CreateCategory";
export default function ListCategories(props) {
function handleClick(category){
props.setFilter(true)
props.filterNotes(category)
}
return (
<div className="category-group">
<CreateCategory/>
<div className="btn-group">
{props.categories.map((categoryItem, index) =>{
return(
<button onClick={() => {handleClick(categoryItem.category)}}>{categoryItem.category}</button>
)
})}
</div>
</div>
)
}
I'm not sure what the best practice is with such behaviour - do I get the notes from the database each time as I'm doing now or should I do something completely different to avoid the double-click function call?
Thanks in advance for any suggestions!
Your issue is this function:
function handleClick(category){
props.setFilter(true)
props.filterNotes(category)
}
Understand that in React, state is only updated after the current execution context is finished. So in handleClick() when you call setFiler(), that linked filterOn state is only updated when the rest of the function body finishes.
so when your filterNotes() function is called, when it evaluates filterOn, it is still false, as it was initially set. After this function has executed, the handleClick() function has also finished, and after this, the filterOn state now equals true
This is why on the second click, the desired rendering effect occurs.
There are multiple ways to get around this, but I normally use 'render/don't-render' state by including it as an embedded expression in the JSX:
<main>
{state && <Component />}
</main>
I hope this helps.
You diagnosed the problem correctly. You shouldn't be using state like you would a variable. State is set asynchronously. So, if you need to fetch some data and filter it, do that and THEN add the data to state.
function filterNotes(category){
fetch('http://localhost:5000/notes')
.then(res => res.json())
.then(json => {
const filtered = json.filter((noteItem) => (noteItem.category === category));
setNotes(filtered);
})
}
}
It's not clear to me why you would need the filterOn state at all.
Depending on how your frequently your data is updated and if you plan on sharing data across users, the answer to this question will vary.
If these notes are specific to the user then you should pull the notes on load and then store them in a local state or store. Write actions that can update the state or store so that this isn't coupled with your react UI rendering. Example: https://redux.js.org/ or https://mobx.js.org/README.html.
Then update that store and your remote database accordingly through dispatching actions. This avoids lots of calls to the database and you can perform your filtering client-side as well. You can then also store data locally for offline use through this method so if it's for a mobile app and they lose internet connection, it'll still render. Access the store's state and update your UI based on that. Specifically the notes and categories.
If you have multiple users accessing the data then you'll need to look at using websockets to send that data across clients in addition to the database. You can add listeners that look for this data and update that store or state that you will have created previously.
There are many approaches to this, this is just an approach I would take.
You could also create a context and provider that maintains your state on the first load and persists after that. Then you can avoid passing down state handlers through props
How to push element inside useState array AND deleting said object in a dynamic matter using React hooks (useState)?
I'm most likely not googling this issue correctly, but after a lot of research I haven't figured out the issue here, so bare with me on this one.
The situation:
I have a wrapper JSX component which holds my React hook (useState). In this WrapperComponent I have the array state which holds the objects I loop over and generate the child components in the JSX code. I pass down my onChangeUpHandler which gets called every time I want to delete a child component from the array.
Wrapper component:
export const WrapperComponent = ({ component }) => {
// ID for component
const { odmParameter } = component;
const [wrappedComponentsArray, setWrappedComponentsArray] = useState([]);
const deleteChildComponent = (uuid) => {
// Logs to array "before" itsself
console.log(wrappedComponentsArray);
/*
Output: [{"uuid":"acc0d4c-165c-7d70-f8e-d745dd361b5"},
{"uuid":"0ed3cc3-7cd-c647-25db-36ed78b5cbd8"]
*/
setWrappedComponentsArray(prevState => prevState.filter(item => item !== uuid));
// After
console.log(wrappedComponentsArray);
/*
Output: [{"uuid":"acc0d4c-165c-7d70-f8e-d745dd361b5",{"uuid":"0ed3cc3-
7cd-c647-25db-36ed78b5cbd8"]
*/
};
const onChangeUpHandler = (event) => {
const { value } = event;
const { uuid } = event;
switch (value) {
case 'delete':
// This method gets hit
deleteChildComponent(uuid);
break;
default:
break;
}
};
const addOnClick = () => {
const objToAdd = {
// Generate uuid for each component
uuid: uuid(),
onChangeOut: onChangeUpHandler,
};
setWrappedComponentsArray(wrappedComponentsArray => [...wrappedComponentsArray, objToAdd]);
// Have also tried this solution with no success
// setWrappedComponentsArray(wrappedComponentsArray.concat(objToAdd));
};
return (
<>
<div className='page-content'>
{/*Loop over useState array*/}
{
wrappedComponentsArray.length > 0 &&
<div>
{wrappedComponentsArray.map((props) => {
return <div className={'page-item'}>
<ChildComponent {...props} />
</div>;
})
}
</div>
}
{/*Add component btn*/}
{wrappedComponentsArray.length > 0 &&
<div className='page-button-container'>
<ButtonContainer
variant={'secondary'}
label={'Add new component'}
onClick={() => addOnClick()}
/>
</div>
}
</div>
</>
);
};
Child component:
export const ChildComponent = ({ uuid, onChangeOut }) => {
return (
<>
<div className={'row-box-item-wrapper'}>
<div className='row-box-item-input-container row-box-item-header'>
<Button
props={
type: 'delete',
info: 'Deletes the child component',
value: 'Delete',
uuid: uuid,
callback: onChangeOut
}
/>
</div>
<div>
{/* Displays generated uuid in the UI */}
{uuid}
</div>
</div>
</>
)
}
As you can see in my UI my adding logic works as expected (code not showing that the first element in the UI are not showing the delete button):
Here is my problem though:
Say I hit the add button on my WrapperComponent three times and adds three objects in my wrappedComponentsArray gets rendered in the UI via my mapping in the JSX in the WrapperComponent.
Then I hit the delete button on the third component and hit the deleteChildComponent() funtion in my parent component, where I console.log my wrappedComponentsArray from my useState.
The problem then occurs because I get this log:
(2) [{…}, {…}]
even though I know the array has three elements in it, and does not contain the third (and therefore get an undefined, when I try to filter it out, via the UUID key.
How do I solve this issue? Hope my code and explanation makes sense, and sorry if this question has already been posted, which I suspect it has.
You provided bad filter inside deleteChildComponent, rewrite to this:
setWrappedComponentsArray(prevState => prevState.filter(item => item.uuid !== uuid));
You did item !== uuid, instead of item.uuid !== uuid
Please try this, i hope this works
const deleteChildComponent = (uuid) => {
console.log(wrappedComponentsArray);
setWrappedComponentsArray(wrappedComponentsArray.filter(item => item !== uuid));
};
After update
const deleteChildComponent = (uuid) => {
console.log(wrappedComponentsArray);
setWrappedComponentsArray(wrappedComponentsArray.filter(item => item.uuid !== uuid)); // item replaced to item.uuid
};
Huge shoutout to #Jay Vaghasiya for the help.
Thanks to his expertise we managed to find the solution.
First of, I wasn't passing the uuid reference properly. The correct was, when making the objects, and pushing them to the array, we passed the uuid like this:
const addOnClick = () => {
const objToAdd = {
// Generate uuid for each component
uuid: uuid(),
parentOdmParameter: odmParameter,
onChangeOut: function(el) { onChangeUpHandler(el, this.uuid)}
};
setWrappedComponentsArray([...wrappedComponentsArray, objToAdd]);
};
When calling to delete function the function that worked for us, was the following:
const deleteChildComponent = (uuid) => {
setWrappedComponentsArray(item => item.filter(__item => __item.uuid !== uuid)); // item replaced to item.uuid
};
I want to build a dashboard for a blog. I have a page, listing all blog posts using a component for each list item. Now, inside each list item, I have a button to delete the post.
So far, everything is working. The post gets deleted, and if I reload the page, it is gone from the list. But I can't get it to re-render the page automatically, after deleting a post. I kind of cheated here using window.location.reload() but there has to be a better way?
This is my Page to build the list of all Posts
import {
CCol,
CContainer,
CRow,
CTable,
CTableHead,
CTableRow,
CTableHeaderCell,
CTableBody,
} from "#coreui/react";
import { useState, useEffect } from "react";
import DashboardSidebar from "../../components/dashboard/Sidebar";
import { getAllBlogPosts } from "../../services/blogService";
import BlogListItem from "../../components/dashboard/blog/BlogListItem";
import "./Dashboard.scss";
const AdminBlogListView = () => {
const [blogposts, setBlogposts] = useState([]);
useEffect(() => {
getBlogPosts();
}, []);
async function getBlogPosts() {
const response = await getAllBlogPosts();
setBlogposts(response.data);
}
// console.log(blogposts);
return (
<div className="adminContainer">
<div className="adminSidebar">
<DashboardSidebar />
</div>
<div className="adminContent">
<CContainer fluid>
<CRow className="mb-3">
<CCol>
<CTable>
<CTableHead>
<CTableRow>
<CTableHeaderCell scope="col">#</CTableHeaderCell>
<CTableHeaderCell scope="col">Titel</CTableHeaderCell>
<CTableHeaderCell scope="col">Content</CTableHeaderCell>
<CTableHeaderCell scope="col"></CTableHeaderCell>
</CTableRow>
</CTableHead>
<CTableBody>
{blogposts.map((post) => {
return <BlogListItem key={post._id} post={post} />;
})}
</CTableBody>
</CTable>
</CCol>
</CRow>
</CContainer>
</div>
</div>
);
};
export default AdminBlogListView;
And this is the BlogListItem Component
import { useState, useEffect } from "react";
import {
CTableRow,
CTableHeaderCell,
CTableDataCell,
} from "#coreui/react";
import CIcon from "#coreui/icons-react";
import * as icon from "#coreui/icons";
import {
deleteBlogPost,
getBlogPostById,
// updateBlogPost,
} from "../../../services/blogService";
import { useNavigate } from "react-router-dom";
const BlogListItem = (props) => {
const id = props.post._id;
const [visible, setVisible] = useState(false);
const [post, setPost] = useState({
title: "",
content: "",
});
useEffect(() => {
getBlogPostById(id)
.then((response) => setPost(response.data))
.catch((error) => console.log(error));
}, []);
const handleDelete = async (event) => {
event.preventDefault();
const choice = window.confirm("Are you sure you want to delete this post?");
if (!choice) return;
await deleteBlogPost(post._id);
window.location.reload();
};
return (
<>
<CTableRow>
<CTableHeaderCell scope="row">1</CTableHeaderCell>
<CTableDataCell>{post.title}</CTableDataCell>
<CTableDataCell>{post.content}</CTableDataCell>
<CTableDataCell>
<CIcon
icon={icon.cilPencil}
size="lg"
onClick={() => setVisible(!visible)}
/>
<CIcon
icon={icon.cilTrash}
className="deleteButton"
size="lg"
color=""
onClick={handleDelete}
/>
</CTableDataCell>
</CTableRow>
</>
);
};
export default BlogListItem;
What can I do instead of window.location.reload() to render the AdminBlogListView after deleting an item? I tried using useNavigate() but that doesn't do anything
Thanks in advance :)
You can pass a reference to a function from the parent component AdminBlogListView into the child component BlogListItem, such that it is invoked when a blog post is deleted. That function will have the effect of either repopulating the blog posts or manually removing it from the data (that implementation bit is up to you).
Solution 1: Repopulate all blog posts on deletion
This is a quick fix with a bit of code smell (because you're essentially querying the server twice: once to delete the post and another to fetch posts again). However it is an escape-hatch type of situation and is simple to implement.
When you are rendering BlogListItem, we can pass a function, say onDelete, which will invoke getBlogPosts() to manually repopulate the blog posts from your server:
<BlogListItem key={post._id} post={post} onDelete={getBlogPosts} />
Then it is a matter of ensuring BlogListItem invokes onDelete() when deleting a blog post:
const handleDelete = async (event) => {
event.preventDefault();
const choice = window.confirm("Are you sure you want to delete this post?");
if (!choice) return;
await deleteBlogPost(post._id);
// Invoke the passed in `onDelete` function in component props
props.onDelete();
};
Solution 2: Delete a specific blog post by ID in the parent
Similar to the solution above, but ensure that you are passing a function from the parent that can delete a post by a specific ID (from the argument). This saves you an additional trip to the server.
In your component AdminBlogListView, define a function that can mutate the blogposts state by removing a blog post by ID. This can be done by leveraging functional updates:
const onDelete = (id) => {
setBlogposts((currentBlogPosts) => {
const foundBlogPostIndex = currentBlogPosts.findIndex(entry => entry._id === id);
// If we find the blog post with matching ID, remove it
if (foundBlogPostIndex !== -1) currentBlogPosts.splice(foundBlogPostIndex, 1);
return currentBlogPosts;
})
}
NOTE: The code above assumes that the blog post ID is stored in the _id key. I have simply inferred that from your code, since you have not shared the shape of the data.
Then in your BlogListItem component, it's the same logic as solution #1, but you need to pass the ID into it when invoking it:
const handleDelete = async (event) => {
event.preventDefault();
const choice = window.confirm("Are you sure you want to delete this post?");
if (!choice) return;
await deleteBlogPost(post._id);
// Invoke the passed in `onDelete` function in component props with post ID as an argument
props.onDelete(post._id);
};
Hello I am building photo gallery where I would like to add feature that user will be able filter by Category. I tried some solutions but there are two bugs that I am not able to fix. First is that if I go to the GalleryPage (using Swtich) it does NOT render dynamically added buttons from FilterButton component. I have to click one more time on the link and then it DOES render the buttons. I dont know why it does not work on the first render.
Other issue is that I am able to filter by category but it causes the infinite loop in the useEffect and I dont know how to fix it.
I have got GalleryPage component where I am getting data from API and parsing the data for using later in other components. Here it seems that is all working fine.
const GalleryPage = () => {
const url = 'someurl';
const [data, setData] = useState([]);
const [categoryList, setCategoryList] = useState([]);
const [category, setCategory] = useState('All');
useEffect(() => {
const fetchData = async () => {
const result = await axios(url,);
setData(result.data)
result.data.forEach(item => {
imageUrl.push(item.image)
if (categoryList.indexOf(item.group) === -1) {
categoryList.push(item.group)
}
})
}
fetchData();
}, [])
return (
<FilterButton setCategory={setCategory} categoryList={categoryList}/>
<Gallery data={data} category={category}/>
)
}
If I go to the GalleryPage the h3 and 'All' button is rendered. But I have to click on the link one more time to render the buttons inside the map function:
const FilterButton = ({setCategory, categoryList}) => {
return(
<h3>Gallery</h3>
<button onClick={()=> setCategory('All')}>All</button>
{categoryList.map(item => (
<button key={item} onClick={()=> setCategory(item)}>{item}</button>
))}
)
};
export default FilterButton;
And here I am not able to fix the infinite loop:
const Gallery = ({data, category}) => {
const [photos, setPhotos] = useState([]);
useEffect(()=>{
let temp = []
if (category === 'All'){
setPhotos(data)
}else{
data.map(item => {
temp.push(item)
})
}
setPhotos(temp)
})
return(
photos.map((item =>
<img key={item.id} src={item.image}/>
))
)
};
export default Gallery;
If I add empty array to the useEffect it does not work at all. Also I am using styled components and framer motion but it should not have affect on this I hope.
First, I see that you're never setting your state for categoryList.
After modifying categoryList, you should call setCategoryList() with the new category list. This way, the state variable will be 'remembered' when the component is re-rendered.
You can read about the useState hook here.
Additionally, for the useEffect hook, the 'empty array' you pass in at the end is actually an array of variables to 'watch' for changes. If you pass an empty array, the useEffect will only run once, at the first page load. However, you can pass in something like [category] so that the useEffect is only called when the category variable is modified, which I persume is what you want to do.
Edit: I don't understand the reason for downvotes, this was a good question and no other questions on this site solved my issue. I simply preloaded the data to solve my issue but that still doesn't solve the problem without using functional components.
I'm trying to pass users last message into the ListItem subtitle prop but I can't seem to find a way to return the value from the promise/then call. It's returning a promise instead of the value which gives me a "failed prop type". I thought about using a state but then I don't think I could call the function inside the ListItem component anymore.
getMsg = id => {
const m = fireStoreDB
.getUserLastMessage(fireStoreDB.getUID, id)
.then(msg => {
return msg;
});
return m;
};
renderItem = ({ item }) => (
<ListItem
onPress={() => {
this.props.navigation.navigate('Chat', {
userTo: item.id,
UserToUsername: item.username
});
}}
title={item.username}
subtitle={this.getMsg(item.id)} // failed prop type
bottomDivider
chevron
/>
);
You could only do it that way if ListItem expected to see a promise for its subtitle property, which I'm guessing it doesn't. ;-) (Guessing because I haven't played with React Native yet. React, but not React Native.)
Instead, the component will need to have two states:
The subtitle isn't loaded yet
The subtitle is loaded
...and render each of those states. If you don't want the component to have state, then you need to handle the async query in the parent component and only render this component when you have the information it needs.
If the 'last message' is something specific to only the ListItem component and not something you have on hand already, you might want to let the list item make the network request on its own. I would move the function inside ListItem. You'll need to set up some state to hold this value and possibly do some conditional rendering. Then you'll need to call this function when the component is mounted. I'm assuming you're using functional components, so useEffect() should help you out here:
//put this is a library of custom hooks you may want to use
// this in other places
const useIsMounted = () => {
const isMounted = useRef(false);
useEffect(() => {
isMounted.current = true;
return () => (isMounted.current = false);
}, []);
return isMounted;
};
const ListItem = ({
title,
bottomDivider,
chevron,
onPress,
id, //hae to pass id to ListItem
}) => {
const [lastMessage, setLastMessage] = useState(null);
const isMounted = useIsMounted();
React.useEffect(() => {
async function get() {
const m = await fireStoreDB.getUserLastMessage(
fireStoreDB.getUID,
id
);
//before setting state check if component is still mounted
if (isMounted.current) {
setLastMessage(m);
}
}
get();
}, [id, isMounted]);
return lastMessage ? <Text>DO SOMETHING</Text> : null;
};
I fixed the issue by using that promise method inside another promise method that I had on componentDidMount and added user's last message as an extra field for all users. That way I have all users info in one state to populate the ListItem.
componentDidMount() {
fireStoreDB
.getAllUsersExceptCurrent()
.then(users =>
Promise.all(
users.map(({ id, username }) =>
fireStoreDB
.getUserLastMessage(fireStoreDB.getUID, id)
.then(message => ({ id, username, message }))
)
)
)
.then(usersInfo => {
this.setState({ usersInfo });
});
}
renderItem = ({ item }) => (
<ListItem
onPress={() => {
this.props.navigation.navigate('Chat', {
userTo: item.id,
UserToUsername: item.username
});
}}
title={item.username}
subtitle={item.message}
bottomDivider
chevron
/>
);