React fetch data in server before render

Question

I\'m new to reactjs, I want to fetch data in server, so that it will send page with data to client.

It is OK when the function getDefaultProps return dummy data like

Answer 1

In React, props are used for component parameters not for handling data. There is a separate construct for that called state. Whenever you update state the component basically re-renders itself according to the new values.

var BookList = React.createClass({
  // Fetches the book list from the server
  getBookList: function() {
    superagent.get('http://localhost:3100/api/books')
      .accept('json')
      .end(function(err, res) {
        if (err) throw err;

        this.setBookListState(res);
      });
  },
  // Custom function we'll use to update the component state
  setBookListState: function(books) {
    this.setState({
      books: books.data
    });
  },
  // React exposes this function to allow you to set the default state
  // of your component
  getInitialState: function() {
    return {
      books: []
    };
  },
  // React exposes this function, which you can think of as the
  // constructor of your component. Call for your data here.
  componentDidMount: function() {
    this.getBookList();
  },
  render: function() {
    var books = this.state.books.map(function(book) {
      return (
        <li key={book.key}>{book.name}</li>
      );
    });

    return (
      <div>
        <ul>
          {books}
        </ul>
      </div>
    );
  }
});

Answer 2

You can use redial package for prefetching data on the server before attempting to render

Answer 3

The best answer I use to receive data from server and display it

 constructor(props){
            super(props);
            this.state = {
                items2 : [{}],
                isLoading: true
            }

        }

componentWillMount (){
 axios({
            method: 'get',
            responseType: 'json',
            url: '....',

        })
            .then(response => {
                self.setState({
                    items2: response ,
                    isLoading: false
                });
                console.log("Asmaa Almadhoun *** : " + self.state.items2);
            })
            .catch(error => {
                console.log("Error *** : " + error);
            });
    })}



    render() {
       return(
       { this.state.isLoading &&
                    <i className="fa fa-spinner fa-spin"></i>

                }
                { !this.state.isLoading &&
            //external component passing Server data to its classes
                     <TestDynamic  items={this.state.items2}/> 
                }
         ) }

Answer 4

Responded to a similar question with a potentially simple solution to this if anyone is still after an answer, the catch is it involves the use of redux-sagas:

https://stackoverflow.com/a/38701184/978306

Or just skip straight to the article I wrote on the topic:

https://medium.com/@navgarcha7891/react-server-side-rendering-with-simple-redux-store-hydration-9f77ab66900a

Answer 5

A very simple example of this

import React, { Component } from 'react';
import { View, Text } from 'react-native';

export default class App extends React.Component  {

    constructor(props) {
      super(props);

      this.state = {
        data : null
      };
    }

    componentWillMount() {
        this.renderMyData();
    }

    renderMyData(){
        fetch('https://your url')
            .then((response) => response.json())
            .then((responseJson) => {
              this.setState({ data : responseJson })
            })
            .catch((error) => {
              console.error(error);
            });
    }

    render(){
        return(
            <View>
                {this.state.data ? <MyComponent data={this.state.data} /> : <MyLoadingComponnents /> }
            </View>
        );
    }
}

Answer 6

I've just stumbled upon this problem too, learning React, and solved it by showing spinner until the data is ready.

    render() {
    if (this.state.data === null) {
        return (
            <div className="MyView">
                <Spinner/>
            </div>
        );
    }
    else {
        return(
            <div className="MyView">
                <ReactJson src={this.state.data}/>
            </div>
        );
    }
}