Develop Reference

How to change the url in the fetch statement React JS using props?

So, I'm trying to make this ApiCalls class, which was working if I just plugged in a url into the fetch statement, but I'm trying to make it so that I can change the url depending on which button I press on the site. I want to call ApiCalls in the SearchButtons.js class where in each click function I'll specify the url I want to use. It's not working and it's definitely something to do with the props, idk how else to pass in the a
constructor(props) {
super(props);
this.state = {
error: null,
isLoaded: false,
items: [],
//url: {props.url}////////////////////////////// this doesnt work.
//if i dont use brackets it compiles, but I get this error
//Error: Unexpected token < in JSON at position 0
};
}
componentDidMount() {
fetch(this.url)//////////////////////////////////////////////
.then(res => res.json())
.then(
(result) => {
this.setState({
isLoaded: true,
items: result.articles
});
},
(error) => {
this.setState({
isLoaded: true,
error
});
}
)
}
render() {
const { error, isLoaded, items } = this.state;
if (error) {
return <div>Error: {error.message}</div>;
} else if (!isLoaded) {
return <div>Loading...</div>;
} else {
console.log(items);
return (
<ul>
{items.map(item => (
<ArticleCard key={item.title} title={item.title} desc={item.description} imgsrc={item.urlToImage} url={item.url}/>
))}
</ul>
);
}
}
}
export default ApiCalls;
import React, { Component } from 'react';
import ApiCalls from "./ApiCalls";
class SearchButton extends React.Component {
handleClick = () => {
console.log('this is:', this);
return (<ApiCalls url="myUrlHasMyAPIKeySoThisIsAPlaceHolder/>); ////////////////////////
///this is where I want to specify the url
}

You can achieve this by simply doing this.
import React, { Component } from 'react';
import Child from "./ApiCalls";
class SearchButton extends React.Component {
handleClick = () => {
console.log('this is:', this);
return (<ApiCalls url="myUrl"/>);
}
....
And In Child Component.
import React, { Component } from 'react';
class Child extends React.Component {
constructor(props) {
super(props);
this.state = {
error: null,
isLoaded: false,
items: [],
};
}
componentDidMount() {
fetch(this.props.url){/* Access url from props */}
.then(res => res.json())
.then(
(result) => {
this.setState({
isLoaded: true,
items: result.articles
});
},
(error) => {
this.setState({
isLoaded: true,
error
});
}
)
}
....
Hope, this will help you.

How do I manipulate data that is located in state and display to page?

I'm making three separate axios calls that each set the state with some data. Where do I do my data manipulation with the state data not to change the state but to display something else where?
For example out of the transactionItems state, I want to get all transactions for the current date. All transaction items have the date set automatically when its added to the database.
I'm having issues parsing the data because my setstate seems to update 3 times with all the axios calls.
There are other data manipulations I would like to be able to do as well but I feel like I'll hit another roadblock.
import React, { Component } from "react";
import axios from "axios";
import moment from "moment";
import TransactionSummary from "./TransactionSummary";
import BudgetSummary from "./BudgetSummary";
import DebtSummary from "./DebtSummary";
class DashboardTable extends Component {
constructor(props) {
super(props);
this.state = {
transactionItems: [],
budgetItems: [],
debtItems: [],
spentToday: ""
};
}
componentDidMount() {
this.getTransactionData();
this.getBudgetData();
this.getDebtData();
}
getTransactionData = () => {
axios.defaults.headers.common["Authorization"] = localStorage.getItem(
"jwtToken"
);
axios
.get("/api/transactions")
.then(res =>
this.setState({
transactionItems: res.data
})
)
.catch(err => console.log(err));
};
getBudgetData = () => {
axios.defaults.headers.common["Authorization"] = localStorage.getItem(
"jwtToken"
);
axios
.get("/api/budgets")
.then(res =>
this.setState({
budgetItems: res.data
})
)
.catch(err => console.log(err));
};
getDebtData = () => {
axios.defaults.headers.common["Authorization"] = localStorage.getItem(
"jwtToken"
);
axios
.get("/api/debts")
.then(res =>
this.setState({
debtItems: res.data
})
)
.catch(err => console.log(err));
};
render() {
return (
<div>
<div className="content">
<TransactionSummary transactionItems={this.state.transactionItems} />
<BudgetSummary budgetItems={this.state.budgetItems} />
<DebtSummary debtItems={this.state.debtItems} />
</div>
</div>
);
}
}
export default DashboardTable;
Here's DebtSummary component
import React from "react";
const DebtSummary = props => {
let sumOfDebtItems = props.debtItems.reduce((a, c) => {
return a + c["balance"];
}, 0);
return (
<div>
<p>Debt Summary</p>
{sumOfDebtItems}
</div>
);
};
export default DebtSummary;

Like Hemadri said, the easiest way to do this is to move the 3 axios calls into their respective component
You can also move the data manipulation into a separate method and call it in the render method. You can write as many of these as you need, they can all read from the same state variable
DebtSummary example:
import React from "react";
class DebtSummary extends React.Component {
constructor(props) {
super(props);
this.state = {
debtItems: []
}
}
getDebtData = () => {
axios.defaults.headers.common["Authorization"] = localStorage.getItem(
"jwtToken"
);
axios
.get("/api/debts")
.then(res =>
this.setState({
debtItems: res.data
})
)
.catch(err => console.log(err));
};
// Do some data manipulation, in the case computing the debt sum
sumOfDebtItems = () => {
return this.state.debtItems.reduce((a, c) => {
return a + c["balance"];
}, 0);
}
// Load the debt data once the component has mounted
componentDidMount() {
this.getDebtData()
}
render() {
return (
<div>
<p>Debt Summary</p>
{this.sumOfDebtItems()}
</div>
);
}
};
export default DebtSummary;

React Warning: Can't call setState (or forceUpdate) on an unmounted component

I have 2 components:
Orders - fetch some data and display it.
ErrorHandler - In case some error happen on the server, a modal will show and display a message.
The ErrorHandler component is warping the order component
I'm using the axios package to load the data in the Orders component, and I use axios interceptors to setState about the error, and eject once the component unmounted.
When I navigate to the orders components back and forward i sometimes get an error in the console:
Warning: Can't call setState (or forceUpdate) on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.
in Orders (at ErrorHandler.jsx:40)
in Auxiliary (at ErrorHandler.jsx:34)
in _class2 (created by Route)
I tried to solve it by my previous case React Warning: Can only update a mounted or mounting component but here I can't make an axios token by the inspectors. Has anyone solved this issue before?
Here are my components:
Orders:
import React, { Component } from 'react';
import api from '../../api/api';
import Order from '../../components/Order/Order/Order';
import ErrorHandler from '../../hoc/ErrorHandler/ErrorHandler';
class Orders extends Component {
state = {
orders: [],
loading: true
}
componentDidMount() {
api.get('/orders.json')
.then(response => {
const fetchedOrders = [];
if (response && response.data) {
for (let key in response.data) {
fetchedOrders.push({
id: key,
...response.data[key]
});
}
}
this.setState({ loading: false, orders: fetchedOrders });
})
.catch(error => {
this.setState({ loading: false });
});
}
render() {
return (
<div>
{this.state.orders.map(order => {
return (<Order
key={order.id}
ingrediencies={order.ingrediencies}
price={order.price} />);
})}
</div>
);
}
}
export default ErrorHandler(Orders, api);
ErrorHandler:
import React, { Component } from 'react';
import Auxiliary from '../Auxiliary/Auxiliary';
import Modal from '../../components/UI/Modal/Modal';
const ErrorHandler = (WrappedComponent, api) => {
return class extends Component {
requestInterceptors = null;
responseInterceptors = null;
state = {
error: null
};
componentWillMount() {
this.requestInterceptors = api.interceptors.request.use(request => {
this.setState({ error: null });
return request;
});
this.responseInterceptors = api.interceptors.response.use(response => response, error => {
this.setState({ error: error });
});
}
componentWillUnmount() {
api.interceptors.request.eject(this.requestInterceptors);
api.interceptors.response.eject(this.responseInterceptors);
}
errorConfirmedHandler = () => {
this.setState({ error: null });
}
render() {
return (
<Auxiliary>
<Modal
show={this.state.error}
modalClosed={this.errorConfirmedHandler}>
{this.state.error ? this.state.error.message : null}
</Modal>
<WrappedComponent {...this.props} />
</Auxiliary>
);
}
};
};
export default ErrorHandler;

I think that's due to asynchronous call which triggers the setState, it can happen even when the component isn't mounted. To prevent this from happening you can use some kind of flags :
state = {
isMounted: false
}
componentDidMount() {
this.setState({isMounted: true})
}
componentWillUnmount(){
this.state.isMounted = false
}
And later wrap your setState calls with if:
if (this.state.isMounted) {
this.setState({ loading: false, orders: fetchedOrders });
}
Edit - adding functional component example:
function Component() {
const [isMounted, setIsMounted] = React.useState(false);
useEffect(() => {
setIsMounted(true);
return () => {
setIsMounted(false);
}
}, []);
return <div></div>;
}
export default Component;

You can't set state in componentWillMount method. Try to reconsider your application logic and move it into another lifecycle method.

I think rootcause is the same as what I answered yesterday, you need to "cancel" the request on unmount, I do not see if you are doing it for the api.get() call in Orders component.
A note on the Error Handling, It looks overly complicated, I would definitely encourage looking at ErrorBoundaries provided by React. There is no need for you to have interceptors or a higher order component.
For ErrorBoundaries, React introduced a lifecycle method called: componentDidCatch.
You can use it to simplify your ErrorHandler code to:
class ErrorHandler extends React.Component {
constructor(props) {
super(props);
this.state = { hasError: false };
}
componentDidCatch(error, info) {
this.setState({ hasError: true, errorMessage : error.message });
}
render() {
if (this.state.hasError) {
return <Modal
modalClosed={() => console.log('What do you want user to do? Retry or go back? Use appropriate method logic as per your need.')}>
{this.state.errorMessage ? this.state.errorMessage : null}
</Modal>
}
return this.props.children;
}
}
Then in your Orders Component:
class Orders extends Component {
let cancel;
state = {
orders: [],
loading: true
}
componentDidMount() {
this.asyncRequest = api.get('/orders.json', {
cancelToken: new CancelToken(function executor(c) {
// An executor function receives a cancel function as a parameter
cancel = c;
})
})
.then(response => {
const fetchedOrders = [];
if (response && response.data) {
for (let key in response.data) {
fetchedOrders.push({
id: key,
...response.data[key]
});
}
}
this.setState({ loading: false, orders: fetchedOrders });
})
.catch(error => {
this.setState({ loading: false });
// please check the syntax, I don't remember if it is throw or throw new
throw error;
});
}
componentWillUnmount() {
if (this.asyncRequest) {
cancel();
}
}
render() {
return (
<div>
{this.state.orders.map(order => {
return (<Order
key={order.id}
ingrediencies={order.ingrediencies}
price={order.price} />);
})}
</div>
);
}
}
And use it in your code as:
<ErrorHandler>
<Orders />
</ErrorHandler>

ReactJs - How to complete onClick before download - href

I have a simple React button component that when clicked should retrieve and download data on the client browser. The problem I am experiencing is that the download is triggered and the csv file downloaded before the data is passed into the href.
Here is my component:
import { Component } from 'react';
import { connect } from 'react-redux';
import { PropTypes } from 'prop-types';
import { ManageUsersSelectors } from 'selectors/Users';
import { BatchRoleActions } from 'actions/Users';
class UsersExportButton extends Component {
constructor() {
super();
this.state = {
users: ''
};
}
getUsers(){
const { userIds } = this.props;
BatchRoleActions.getAllRoleUsers(userIds)
.then((users) => {
this.setState({ users: users});
return this.state.users;
});
}
render() {
return (
<div className="roles-export-button">
<a className="button button-default" href={this.state.users} download={'roles.csv'} onClick={() => this.getUsers()} return true>Export Csv</a>
</div>
);
}
}
function mapStateToProps(state) {
const userIds = ManageUsersSelectors.batchUserIdsSelector(state);
return {
userIds: userIds
};
}
UsersExportButton.propTypes = {
text: PropTypes.string.isRequired,
data: PropTypes.array
};
export default connect(mapStateToProps)(UsersExportButton);
How can I get the getUsers()/onClick function to complete the data retrieval step before downloading?
When i debug my code I can see that the getUsers function returns data - however after the download is triggered

Make sure to bind this to your functions. In your constructor you can do:
constructor() {
super();
this.state = {
users: ''
};
this.getUsers = this.getUsers.bind(this);
}
or you can use the bind this function:
getUsers = () => {
const { userIds } = this.props;
BatchRoleActions.getAllRoleUsers(userIds)
.then((users) => {
this.setState({ users: users});
return this.state.users; // This should be removed, you can use this.state.users throughout this component.
});
}

Why not get the user data in the componentDidMount lifecycle method? It doesn't look like it needs to be called onClick.
{
// ...
componentDidMount() {
this.getUsers();
}
// ...
render() {
return (
<div className="roles-export-button">
<a className="button button-default" href={this.state.users} download={'roles.csv'}>Export Csv</a>
</div>
)
}
}

How about handling the default "link" behaviour manually to get more control? Also you should probably try to access state after setState has been executed via its callback.
e.g.
getUsers(cb){
const { userIds } = this.props;
BatchRoleActions.getAllRoleUsers(userIds)
.then((users) => {
// note the callback of setState which is invoked
// when this.state has been set
this.setState({ users: users }, cb);
});
}
const handleClick = () => {
this.getUsers(() => {
window.open(this.state.whatever)
})
}
<span onClick={handleClick}>Export Csv</span>

React.js - Loading single post data from API correctly

I am fairly new to React, and trying to work my way through how I should properly be loading data from my API for a single post.
I have read that I should be using "componentDidMount" to make my GET request to the API, but the request is not finished by the time the component renders. So my code below does not work, as I am recieving the error: "Cannot read property setState of undefined".
What I am doing wrong here? Should I be calling setState from somewhere else? My simple component is below - thanks.
import React from 'react';
import Header from './Header';
import axios from 'axios';
class SingleListing extends React.Component {
constructor(props) {
super(props);
this.state = {
listingData: {}
}
}
componentDidMount() {
// Get ID from URL
var URLsegments = this.props.location.pathname.slice(1).split('/');
// Load the listing data
axios.get('/api/listing/' + URLsegments[1])
.then(function(res){
let listingDataObject = res.data;
console.log(listingDataObject);
this.setState({
listingData: listingDataObject
});
})
.catch(function(err){
console.log(err);
});
}
render() {
console.log('helsdfdsfsdflssosso');
console.log(this.state.listingData);
return (
<div className="SingleListing">
<Header />
<div className="container">
<div>Property Address: {this.state.listingData.propertyAddress}</div>
This is a single listing
</div>
</div>
)
}
}
export default SingleListing;

You just need to change what you render depending on whether the data is loaded or not yet.
Also, you should use arrow functions when handling the axios response, otherwise this is not set correctly.
class SingleListing extends React.Component {
constructor(props) {
super(props);
this.state = {
listingData: null,
};
}
componentDidMount() {
// Get ID from URL
const URLsegments = this.props.location.pathname.slice(1).split('/');
// Load the listing data
axios
.get(`/api/listing/${URLsegments[1]}`)
.then(res => {
const listingDataObject = res.data;
console.log(listingDataObject);
this.setState({
listingData: listingDataObject,
});
})
.catch(err => {
console.log(err);
});
}
render() {
const isDataLoaded = this.state.listingData;
if (!isDataLoaded) {
return <div>Loading...</div>;
}
return (
<div className="SingleListing">
<Header />
<div className="container">
<div>Property Address: {this.state.listingData.propertyAddress}</div>
This is a single listing
</div>
</div>
);
}
}
export default SingleListing;

this is out of scope you need to include it. here is a solution using es2015 arrow functions =>
axios.get('/api/listing/' + URLsegments[1])
.then((res) => {
let listingDataObject = res.data;
console.log(listingDataObject);
this.setState({
listingData: listingDataObject
});
})
.catch((err) => {
console.log(err);
});