code using useParams, useEffect and useState hooks - reactjs

Question

Can someone please tell me the equivalent code using hooks for the following:
componentDidMount() {
const { match: { params } } = this.props;
axios.get(`/api/users/${params.userId}`)
.then(({ data: user }) => {
console.log('user', user);
this.setState({ user });
});
}

Answer 1

The exact functionality to match your class component into a functional component with hooks would be the following:
import * as React from "react";
import { useParams } from "react-router-dom";
const Component = () => {
const { userId } = useParams();
const [state, setState] = React.useState({ user: null });
React.useEffect(() => {
axios.get(`/api/users/${userId}`)
.then(({ data: user }) => {
console.log('user', user);
setState({ user });
});
}, []);
}
React.useEffect(() => {}, []) with an empty dependency array essentially works the same way as the componentDidMount lifecycle method.
The React.useState hook returns an array with the state and a method to update the state setState.
References:
https://reactjs.org/docs/hooks-state.html
https://reactjs.org/docs/hooks-effect.html
As an aside, and pointed out by #Yoshi:
The snippet provided is error prone, and the "moving to hooks" snippet will have the same errors that occur in the example. For example, as the request is in componentDidMount, if the userId changes it won't trigger a fetch to get the user data for the userId. To ensure this works in the hook, all you need to do is provide the userId in the dependency array in the useEffect...
const latestRequest = React.useRef(null);
React.useEffect(() => {
latestRequest.current = userId;
axios.get(`/api/users/${userId}`)
.then(({ data: user }) => {
if (latestRequest.current == userId) {
setState({ user });
}
});
}, [userId]);