I'm building a search field that is fetching from a data base upon users input and I'm struggling a bit. At the moment, it is fetching data in every keystroke, which is not ideal. I have looked at different answers and it seems that the best option is to do this in componentDidUpdate() and get a ref of the input feel to compare this with the current value through a setTimeout().
I have tried this, but I'm still fetching during every keystroke, not sure why? See a sample of the component below:
class ItemsHolder extends Component {
componentDidMount() {
//ensures the page is reloaded at the top when routing
window.scrollTo(0, 0);
this.props.onFetchItems(this.props.search);
}
componentDidUpdate(prevProps, prevState) {
if (prevProps.search !== this.props.search) {
console.log(
this.props.search ===
this.props.searchRef.current.props.value.toUpperCase()
);
setTimeout(() => {
console.log(
this.props.search ===
this.props.searchRef.current.props.value.toUpperCase()
);
if (
this.props.search ===
this.props.searchRef.current.props.value.toUpperCase()
) {
this.props.onFetchItems(this.props.search, this.props.category);
}
}, 500);
}
}
I'm using Redux for state management. Here is the function that is called when fetching items:
export const fetchItemsFromServer = (search) => {
return (dispatch) => {
dispatch(fetchItemsStart());
const query =
search.length === 0 ? '' : `?orderBy="country"&equalTo="${search}"`;
axios
.get('/items.json' + query)
.then((res) => {
const fetchedItems = [];
for (let item in res.data) {
fetchedItems.push({
...res.data[item],
id: item,
});
}
dispatch(fetchItemsSuccess(fetchedItems));
})
.catch((error) => {
dispatch(fetchItemsFail(error));
});
};
};
This is how I'm setting the ref in the search component:
class Search extends Component {
constructor(props) {
super(props);
this.searchInput = React.createRef();
}
componentDidMount() {
this.props.onSetRef(this.searchInput);
}
render() {
return (
<Input
ref={this.searchInput}
toolbar
elementType={this.props.inputC.elementType}
elementConfig={this.props.inputC.elementConfig}
value={this.props.inputC.value}
changed={(event) => this.props.onChangedHandler(event)}
/>
);
}
}
Based on a tutorial I found this should work. For your reference, see the code from this tutorial. I don't see why wouldn't the above work. The only difference is that the tutorial uses hooks.
const Search = React.memo(props => {
const { onLoadIngredients } = props;
const [enteredFilter, setEnteredFilter] = useState('');
const inputRef = useRef();
useEffect(() => {
const timer = setTimeout(() => {
if (enteredFilter === inputRef.current.value) {
const query =
enteredFilter.length === 0
? ''
: `?orderBy="title"&equalTo="${enteredFilter}"`;
fetch(
'https://react-hooks-update.firebaseio.com/ingredients.json' + query
)
.then(response => response.json())
.then(responseData => {
const loadedIngredients = [];
for (const key in responseData) {
loadedIngredients.push({
id: key,
title: responseData[key].title,
amount: responseData[key].amount
});
}
onLoadIngredients(loadedIngredients);
});
}
}, 500);
return () => {
clearTimeout(timer);
};
}, [enteredFilter, onLoadIngredients, inputRef]);
Following recommendation to debounceInput:
import React, { Component } from 'react';
// import classes from './Search.css';
import Input from '../../UI/Input/Input';
// redux
import * as actions from '../../../store/actions/index';
import { connect } from 'react-redux';
class Search extends Component {
componentDidUpdate(prevProps, prevState) {
if (prevProps.search !== this.props.search) {
this.props.onFetchItems(this.props.search, this.props.category);
}
}
debounceInput = (fn, delay) => {
let timerId;
return (...args) => {
clearTimeout(timerId);
timerId = setTimeout(() => fn(...args), delay);
};
};
render() {
return (
<Input
toolbar
elementType={this.props.inputC.elementType}
elementConfig={this.props.inputC.elementConfig}
value={this.props.inputC.value}
changed={(event) =>
this.debounceInput(this.props.onChangedHandler(event), 500)
}
/>
);
}
}
const mapStateToProps = (state) => {
return {
inputC: state.filtersR.inputConfig,
search: state.filtersR.search,
};
};
const mapDispatchToProps = (dispatch) => {
return {
onChangedHandler: (event) => dispatch(actions.inputHandler(event)),
onFetchItems: (search, category) =>
dispatch(actions.fetchItemsFromServer(search, category)),
};
};
export default connect(mapStateToProps, mapDispatchToProps)(Search);
Here is the final solution after help here:
import React, { Component } from 'react';
// import classes from './Search.css';
import Input from '../../UI/Input/Input';
// redux
import * as actions from '../../../store/actions/index';
import { connect } from 'react-redux';
const debounceInput = (fn, delay) => {
let timerId;
return (...args) => {
clearTimeout(timerId);
timerId = setTimeout(() => fn(...args), delay);
};
};
class Search extends Component {
componentDidUpdate(prevProps, _prevState) {
if (prevProps.search !== this.props.search) {
this.responseHandler();
}
}
responseHandler = debounceInput(() => {
this.props.onFetchItems(this.props.search, this.props.category);
}, 1000);
render() {
return (
<Input
toolbar
elementType={this.props.inputC.elementType}
elementConfig={this.props.inputC.elementConfig}
value={this.props.inputC.value}
changed={(event) => this.props.onChangedHandler(event)}
/>
);
}
}
const mapStateToProps = (state) => {
return {
inputC: state.filtersR.inputConfig,
search: state.filtersR.search,
};
};
const mapDispatchToProps = (dispatch) => {
return {
onChangedHandler: (event) => dispatch(actions.inputHandler(event)),
onFetchItems: (search, category) =>
dispatch(actions.fetchItemsFromServer(search, category)),
};
};
export default connect(mapStateToProps, mapDispatchToProps)(Search);
You really just need to debounce your input's onChange
handler, or better, the function that is actually doing the asynchronous work.
Very simple debouncing higher order function:
const debounce = (fn, delay) => {
let timerId;
return (...args) => {
clearTimeout(timerId);
timerId = setTimeout(() => fn(...args), delay);
}
};
Example Use:
fetchData = debounce(() => fetch(.....).then(....), 500);
componentDidUpdate(.......) {
// input value different, call fetchData
}
<Input
toolbar
elementType={this.props.inputC.elementType}
elementConfig={this.props.inputC.elementConfig}
value={this.props.inputC.value}
changed={this.props.onChangedHandler}
/>
const debounce = (fn, delay) => {
let timerId;
return (...args) => {
clearTimeout(timerId);
timerId = setTimeout(fn, delay, [...args]);
};
};
const fetch = (url, options) => {
console.log("Fetching", url);
return new Promise((resolve) => {
setTimeout(() => {
console.log("Fetch Resolved");
resolve(`response - ${Math.floor(Math.random() * 1000)}`);
}, 2000);
});
};
export default class App extends Component {
state = {
search: "",
response: ""
};
changeHandler = (e) => {
const { value } = e.target;
console.log("search", value);
this.setState({ search: value });
};
fetchData = debounce(() => {
const { search } = this.state;
const query = search.length ? `?orderBy="country"&equalTo="${search}"` : "";
fetch(
"https://react-hooks-update.firebaseio.com/ingredients.json" + query
).then((response) => this.setState({ response }));
}, 500);
componentDidUpdate(prevProps, prevState) {
if (prevState.search !== this.state.search) {
if (this.state.response) {
this.setState({ response: "" });
}
this.fetchData();
}
}
render() {
const { response, search } = this.state;
return (
<div className="App">
<h1>Hello CodeSandbox</h1>
<h2>Start editing to see some magic happen!</h2>
<label>
Search
<input type="text" value={search} onChange={this.changeHandler} />
</label>
<div>Debounced Response: {response}</div>
</div>
);
}
}