what is right way to do API call in react js?

2020/11/17 21:41 · javascript ·  · 0评论

I have recently moved from Angular to ReactJs. I am using jQuery for API calls. I have an API which returns a random user list that is to be printed in a list.

I am not sure how to write my API calls. What is best practice for this?

I tried the following but I am not getting any output. I am open to implementing alternative API libraries if necessary.

Below is my code:

import React from 'react';

export default class UserList extends React.Component {    
  constructor(props) {
    super(props);
    this.state = {
      person: []
    };
  }

  UserList(){
    return $.getJSON('https://randomuser.me/api/')
    .then(function(data) {
      return data.results;
    });
  }

  render() {
    this.UserList().then(function(res){
      this.state = {person: res};
    });
    return (
      <div id="layout-content" className="layout-content-wrapper">
        <div className="panel-list">
          {this.state.person.map((item, i) =>{
            return(
              <h1>{item.name.first}</h1>
              <span>{item.cell}, {item.email}</span>
            )
          })}
        <div>
      </div>
    )
  }
}

In this case, you can do ajax call inside componentDidMount, and then update state

export default class UserList extends React.Component {
  constructor(props) {
    super(props);

    this.state = {person: []};
  }

  componentDidMount() {
    this.UserList();
  }

  UserList() {
    $.getJSON('https://randomuser.me/api/')
      .then(({ results }) => this.setState({ person: results }));
  }

  render() {
    const persons = this.state.person.map((item, i) => (
      <div>
        <h1>{ item.name.first }</h1>
        <span>{ item.cell }, { item.email }</span>
      </div>
    ));

    return (
      <div id="layout-content" className="layout-content-wrapper">
        <div className="panel-list">{ persons }</div>
      </div>
    );
  }
}

You may want to check out the Flux Architecture. I also recommend checking out React-Redux Implementation. Put your api calls in your actions. It is much more cleaner than putting it all in the component.

Actions are sort of helper methods that you can call to change your application state or do api calls.

Use fetch method inside componentDidMount to update state:

componentDidMount(){
  fetch('https://randomuser.me/api/')
      .then(({ results }) => this.setState({ person: results }));
}

This discussion has been for a while and @Alexander T.'s answer provided a good guide to follow for newer of React like me. And I'm gonna share some additional know-hows about calling the same API multiple times to refresh the component, I think it's probably a common problem that newbie may face at the beginning.

componentWillReceiveProps(nextProps), from official documentation :

If you need to update the state in response to prop changes (for
example, to reset it), you may compare this.props and nextProps and
perform state transitions using this.setState() in this method.

We could conclude that here is the place we handle props from the parent component, have API calls, and update state.

Base on @Alexander T.'s example:

export default class UserList extends React.Component {
  constructor(props) {
    super(props);
    this.state = {person: []};
  }

  componentDidMount() {
   //For our first load. 
   this.UserList(this.props.group); //maybe something like "groupOne"
  }

  componentWillReceiveProps(nextProps) {
    // Assuming parameter comes from url.
    // let group = window.location.toString().split("/")[*indexParameterLocated*];
    // this.UserList(group);

    // Assuming parameter comes from props that from parent component.
    let group = nextProps.group; // Maybe something like "groupTwo" 
    this.UserList(group);
  }

  UserList(group) {
    $.getJSON('https://randomuser.me/api/' + group)
      .then(({ results }) => this.setState({ person: results }));
  }

  render() {
    return (...)
  }
}

Update

componentWillReceiveProps() would be deprecated.

Here are only some methods (all of them in Doc) in the life cycle which I think would be related to deploying API in general case:
enter image description here

By referring the diagram above:

  • Deploy API in componentDidMount()

    The proper scenario to have API call here is that the content (from the response of API) of this component will be static, componentDidMount() only fire once while the component is mounting, even new props are passed from parent component or have actions to lead re-rendering.
    The component do check difference to re-render but not re-mount.
    Quote from doc:

If you need to load data from a remote endpoint, this is a good place to
instantiate the network request.


  • Deploy API in static getDerivedStateFromProps(nextProps, prevState)

We should notice that there are two kinds of component updating, setState() in current component would not lead this method to trigger, but re-rendering or new props from parent component do.
We could found out that this method also fires while mounting.

This is a proper place to deploy API if we want to use the current component like a template, and the new parameters for API are props coming from parent component.
We receive a different response from API and return a new state here to change the content of this component.

For example:
We have a dropdown list for different Cars in the parent component, this component needs to show the details of the selected one.


  • Deploy API in componentDidUpdate(prevProps, prevState)

Differ from static getDerivedStateFromProps(), this method is invoked immediately after every rendering except the initial rendering. We could have API calling and render difference in one component.

Extend the previous example:
The component to show Car's details may contain a list of series of this car, if we want to check the 2013 production one, we may click or select or ... the list item to lead a first setState() to reflect this behavior (such as highlighting the list item) in this component, and in the following componentDidUpdate() we send our request with new parameters (state). After getting the response, we setState() again for rendering the different content of the Car details. To prevent the following componentDidUpdate() from causing the infinity loop, we need to compare the state by utilizing prevState at the beginning of this method to decide if we send the API and render the new content.

This method really could be utilized just like static getDerivedStateFromProps() with props, but need to handle the changes of props by utilizing prevProps. And we need to cooperate with componentDidMount() to handle the initial API call.

Quote from doc:

... This is also a good place to do network requests as long as you
compare the current props to previous props ...

I would like you to have a look at redux
http://redux.js.org/index.html

They have very well defined way of handling async calls ie API calls, and instead of using jQuery for API calls, I would like to recommend using fetch or request npm packages, fetch is currently supported by modern browsers, but a shim is also available for server side.

There is also this another amazing package superagent, which has alot many options when making an API request and its very easy to use.

Render function should be pure, it's mean that it only uses state and props to render, never try to modify the state in render, this usually causes ugly bugs and decreases performance significantly. It's also a good point if you separate data-fetching and render concerns in your React App. I recommend you read this article which explains this idea very well. https://medium.com/@learnreact/container-components-c0e67432e005#.sfydn87nm

This part from React v16 documentation will answer your question, read on about componentDidMount():

componentDidMount()

componentDidMount() is invoked immediately after a component is
mounted. Initialization that requires DOM nodes should go here. If you
need to load data from a remote endpoint, this is a good place to
instantiate the network request. This method is a good place to set up
any subscriptions. If you do that, don’t forget to unsubscribe in
componentWillUnmount().

As you see, componentDidMount is considered the best place and cycle to do the api call, also access the node, means by this time it's safe to do the call, update the view or whatever you could do when document is ready, if you are using jQuery, it should somehow remind you document.ready() function, where you could make sure everything is ready for whatever you want to do in your code...

1) You can use Fetch API to fetch data from Endd Points:

Example fetching all Github repose for a user

  /* Fetch GitHub Repos */
  fetchData = () => {

       //show progress bar
      this.setState({ isLoading: true });

      //fetch repos
      fetch(`https://api.github.com/users/hiteshsahu/repos`)
      .then(response => response.json())
      .then(data => {
        if (Array.isArray(data)) {
          console.log(JSON.stringify(data));
          this.setState({ repos: data ,
                         isLoading: false});
        } else {
          this.setState({ repos: [],
                          isLoading: false  
                        });
        }
      });
  };

2) Other Alternative is Axios

Using axios you can cut out the middle step of passing the results of
the http request to the .json() method. Axios just returns the data
object you would expect.

  import axios from "axios";

 /* Fetch GitHub Repos */
  fetchDataWithAxios = () => {

     //show progress bar
      this.setState({ isLoading: true });

      // fetch repos with axios
      axios
          .get(`https://api.github.com/users/hiteshsahu/repos`)
          .then(result => {
            console.log(result);
            this.setState({
              repos: result.data,
              isLoading: false
            });
          })
          .catch(error =>
            this.setState({
              error,
              isLoading: false
            })
          );
}

Now you can choose to fetch data using any of this strategies in componentDidMount

class App extends React.Component {
  state = {
    repos: [],
   isLoading: false
  };

  componentDidMount() {
    this.fetchData ();
  }

Meanwhile you can show progress bar while data is loading

   {this.state.isLoading && <LinearProgress />}

You can also fetch data with hooks in your function components

full example with api call: https://codesandbox.io/s/jvvkoo8pq3

second example: https://jsfiddle.net/bradcypert/jhrt40yv/6/

const Repos = ({user}) => {
  const [repos, setRepos] = React.useState([]);

  React.useEffect(() => {
    const fetchData = async () => {
        const response = await axios.get(`https://api.github.com/users/${user}/repos`);
        setRepos(response.data);
    }

    fetchData();
  }, []);

  return (
  <div>
    {repos.map(repo =>
      <div key={repo.id}>{repo.name}</div>
    )}
  </div>
  );
}

ReactDOM.render(<Repos user="bradcypert" />, document.querySelector("#app"))

As best place and practice for external API calls is React Lifecycle method componentDidMount(), where after the execution of the API call you should update the local state to be triggered new render() method call, then the changes in the updated local state will be applied on the component view.

As other option for initial external data source call in React is pointed the constructor() method of the class. The constructor is the first method executed on initialization of the component object instance. You could see this approach in the documentation examples for Higher-Order Components.

The method componentWillMount() and UNSAFE_componentWillMount() should not be used for external API calls, because they are intended to be deprecated. Here you could see common reasons, why this method will be deprecated.

Anyway you must never use render() method or method directly called from render() as a point for external API call. If you do this your application will be blocked.

A clean way is to make an asynchronous API call inside componentDidMount with try/catch function.

When we called an API, we receive a response. Then we apply JSON method on it, to convert the response into a JavaScript object. Then we take from that response object only his child object named "results" (data.results).

In the beginning we defined "userList" in state as an empty array. As soon as we make the API call and receive data from that API, we assign the "results" to userList using setState method.

Inside the render function we tell that userList will be coming from state. Since the userList is an array of objects we map through it, to display a picture, a name and a phone number of each object "user". To retrieve this information we use dot notation (e.g. user.phone).

NOTE: depending on your API, your response may look different. Console.log the whole "response" to see which variables you need from it, and then assign them in setState.

UserList.js

import React, { Component } from "react";

export default class UserList extends Component {
   state = {
      userList: [], // list is empty in the beginning
      error: false
   };

   componentDidMount() {
       this.getUserList(); // function call
   }

   getUserList = async () => {
       try { //try to get data
           const response = await fetch("https://randomuser.me/api/");
           if (response.ok) { // ckeck if status code is 200
               const data = await response.json();
               this.setState({ userList: data.results});
           } else { this.setState({ error: true }) }
       } catch (e) { //code will jump here if there is a network problem
   this.setState({ error: true });
  }
};

  render() {
  const { userList, error } = this.state
      return (
          <div>
            {userList.length > 0 && userList.map(user => (
              <div key={user}>
                  <img src={user.picture.medium} alt="user"/>
                  <div>
                      <div>{user.name.first}{user.name.last}</div>
                      <div>{user.phone}</div>
                      <div>{user.email}</div>
                  </div>
              </div>
            ))}
            {error && <div>Sorry, can not display the data</div>}
          </div>
      )
}}

It would be great to use axios for the api request which supports cancellation, interceptors etc. Along with axios, l use react-redux for state management and redux-saga/redux-thunk for the side effects.

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