Introduction to React v2

Form in React

This section discuss how to implements a form in React.

Allow User to Create Movie

It would be nice if our users can create a movie themselves.

Prerequisite: API Service for Create Movie

Before you can allow user to create movie, first of all the backend API Service must be able to support that.

Luckily our movies API support that. To able to create a movie, install this Restlet Client, which is a Chrome extension to allow you to make API calls.

After the extension is installed,

  1. open the extension by clicking the icon
  2. select "POST" in the METHOD dropdown.
  3. enter the following URL in the URL bar:
    https://react-intro-movies.herokuapp.com/movies
    
  4. add the following content in the BODY field (change it to your favourite movie):
    json
    {
    "name": "More Than Blue",
    "releaseDate": "2018-12-27"
    }
  5. click send

screenshot of Restlet Client

Now when you load your app, you should be see your movie is added.

Add Ajax Call Function to Make the POST Request

Now that we know the actual AJAX call works by using tools, let's proceed to do that with our code.

Create a createMovie function in api.js that will make the request

src/api.js
js
export const createMovie = movie =>
axios
.post('https://react-intro-movies.herokuapp.com/movies', movie)
.then(res => res.data);
  • axios allows you to makes API call with specific method, e.g. get, post, put etc., corresponding to our REST call methods.
  • the second parameter of axios.post is the body of the data that you want to submit.

Create Form Component

Now that we have function to make the API call, let's create the form component.

Add a file movie-form.js with the following content:

src/movie-form.js
jsx
import React from 'react';
import { createMovie } from './api';
export const MovieForm = () => {
const [name, setName] = React.useState('');
const [releaseDate, setReleaseDate] = React.useState('');
const handleSubmit = ev => {
ev.preventDefault();
createMovie({
name,
releaseDate,
}).then(() => {
setName('');
setReleaseDate('');
});
};
return (
<div className="movie-form">
<form onSubmit={handleSubmit}>
<legend>Create Movie</legend>
<div className="field">
<label htmlFor="name" className="label">
Name
</label>
<input
className="input"
value={name}
id="name"
name="name"
onChange={ev => setName(ev.target.value)}
required
/>
</div>
<div className="field">
<label htmlFor="releaseDate" className="label">
Release Date
</label>
<input
className="input"
value={releaseDate}
id="releaseDate"
name="releaseDate"
type="date"
onChange={ev => setReleaseDate(ev.target.value)}
required
/>
</div>
<div className="button-container">
<button type="submit" className="submit-button">
Create
</button>
</div>
</form>
</div>
);
};
  • we declare two states: name and releaseDate for the 2 values for the form.
  • the state value is passed to the value attribute of the input, while the state setter is called in the onChange callback.
  • we define a handleSubmit function, which will be passed to onSubmit props of the form element. When form is submitted, we will call createForm with the state. We call event.preventDefault because by default form submission will cause a page refresh, and we doesn't want that.

Add MovieForm Into App

Now import MovieForm and include it in App component:

src/app.js
jsx
import { MovieForm } from './movie-form';
...
function App() {
const [moviesShown, toggleShowMovies] = useToggle(false);
const { movies, isLoading } = useMovieData();
return (
<div>
<TitleBar>
<h1>React Movie App</h1>
</TitleBar>
<div className="container">
<div>
<div className="button-container">
<Button onClick={toggleShowMovies}>
{moviesShown ? 'Hide' : 'Show'} Movies
</Button>
</div>
{moviesShown && (
<BusyContainer isLoading={isLoading}>
{movies.map(movie => (
<Movie
name={movie.name}
releaseDate={movie.releaseDate}
key={movie.id}
/>
))}
</BusyContainer>
)}
</div>
</div>
<div>
<MovieForm />
</div>
</div>
);
}

Now try to use the form, you can see the page is making the AJAX call, and after you refresh the page, the new movie will be there!

Refresh Movie List after Submission

Currently the movie list is not updated after you create the new movie, which is a bug. Therefore, we need to somehow let me App component know that the MovieForm has created a record, and it should refresh the list. We can achieve this by passing a callback from App to MovieForm.

  1. Update useMovieData custom hook in App to return loadMoviesData:

    src/app.js
    js
    function useMovieData() {
    const [movies, setMovies] = React.useState([]);
    const [isLoading, setIsLoading] = React.useState(true);
    const loadMoviesData = () => {
    setIsLoading(true);
    loadMovies().then(movieData => {
    setMovies(movieData);
    setIsLoading(false);
    });
    };
    React.useEffect(loadMoviesData, []);
    return {
    movies,
    isLoading,
    loadMoviesData,
    };
    }
  2. Pass loadMoviesData function to MovieForm component as onSubmitSuccess props;

    jsx
    function App() {
    const [moviesShown, toggleShowMovies] = useToggle(false);
    const { movies, isLoading, loadMoviesData } = useMovieData();
    return (
    <div>
    <TitleBar>
    <h1>React Movie App</h1>
    </TitleBar>
    <div className="container">
    <div>
    <div className="button-container">
    <Button onClick={toggleShowMovies}>
    {moviesShown ? 'Hide' : 'Show'} Movies
    </Button>
    </div>
    {moviesShown && (
    <BusyContainer isLoading={isLoading}>
    {movies.map(movie => (
    <Movie
    name={movie.name}
    releaseDate={movie.releaseDate}
    key={movie.id}
    />
    ))}
    </BusyContainer>
    )}
    </div>
    </div>
    <div>
    <MovieForm onSubmitSuccess={loadMoviesData} />
    </div>
    </div>
    );
    }
  3. In MovieForm, call onSubmitSuccess when createMovie ajax succeeds:

    src/movie-form.js
    jsx
    export const MovieForm = ({ onSubmitSuccess }) => {
    const [name, setName] = React.useState('');
    const [releaseDate, setReleaseDate] = React.useState('');
    const handleSubmit = ev => {
    ev.preventDefault();
    createMovie({
    name,
    releaseDate
    }).then(() => {
    onSubmitSuccess();
    setName('');
    setReleaseDate('');
    });
    };
    return (
    ...
    );
    }

Now the movie list should be updated once you submit create movie!

Extract Form State to Custom Hook

Let's extract out some code in MovieForm:

src/movie-form.js
jsx
import React from 'react';
import { createMovie } from './api';
const useMovieForm = () => {
const [name, setName] = React.useState('');
const [releaseDate, setReleaseDate] = React.useState('');
return {
setName,
setReleaseDate,
values: {
name,
releaseDate,
},
};
};
export const MovieForm = ({ onSubmitSuccess }) => {
const { values, setName, setReleaseDate } = useMovieForm();
const handleSubmit = ev => {
ev.preventDefault();
createMovie(values).then(() => {
onSubmitSuccess();
setName('');
setReleaseDate('');
});
};
return (
<div className="movie-form">
<form onSubmit={handleSubmit}>
<legend>Create Movie</legend>
<div className="field">
<label htmlFor="name" className="label">
Name
</label>
<input
className="input"
value={values.name}
id="name"
name="name"
onChange={ev => setName(ev.target.value)}
required
/>
</div>
<div className="field">
<label htmlFor="releaseDate" className="label">
Release Date
</label>
<input
className="input"
value={values.releaseDate}
id="releaseDate"
name="releaseDate"
type="date"
onChange={ev => setReleaseDate(ev.target.value)}
required
/>
</div>
<div className="button-container">
<button type="submit" className="submit-button">
Create
</button>
</div>
</form>
</div>
);
};
  • we extract out the two form input states into useMovieForm custom hook, and use that in MovieForm component.

Do It: Create Movie Form

  1. Create MovieForm component will will make API call to backend via createMovie function.
  2. Include MovieForm in App and make sure creation is working.
  3. Enhance application to auto refresh movie list when creation is success.
  4. Extract out form data to useMovieForm custom hook.
Comments
Reply
Leonardo Losoviz on June 28, 2019, 10:26 AM

There is a tiny problem here: values is not declared at the beginning of the code. So its first referencing throws an error, here:

createMovie(values).then(() => {
  setName('');
  setReleaseDate('');
});
Malcolm Kee on June 28, 2019, 1:52 PM

Fixed! Thanks 👍

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